Philosophy is a word derived from the Greek, and literally signifies the love of wisdom. In its usual acceptation, however, it denotes a science, or collection of sciences, of which the universe is the object; and of the term thus employed many definitions have been given, differing from one another according to the different views of their several authors. By Pythagoras, philosophy is defined ἐπιστήμη τῶν ὄντων, the knowledge of things existing; by Cicero, after Plato, "scientia rerum divinarum et humanarum cum causis;" and by the illustrious Bacon, interpretatio naturae. Whether any of these definitions be sufficiently precise, and at the same time sufficiently comprehensive, may perhaps be questioned; but if philosophy in its utmost extent be capable of being adequately defined, it is not here that the definition should be given. "Explanation," says an acute writer,2 is the first office of a teacher; definition, if it be good, is the last of the inquirer after truth; but explanation is one thing, and definition quite another." It may be proper, however, to observe, that the definition given by Cicero is better than that of Pythagoras, because the chief object of the philosopher is to ascertain the causes of things; and in this consists the difference between his studies and those of the natural historian, who merely enumerates phenomena, and arranges them into separate classes.

The principal objects of philosophy are, God, nature, and man. That part of it which treats of God is called Theology; that which treats of nature, Physics and Metaphysics; and that which treats of man, Logic and Ethics. That these are not separate and independent sciences, but, as Bacon expresses it,3 branches from the same trunk, we shall endeavour to show, after we have, agreeably to our usual plan, given a short history of philosophy from the earliest ages to the present day.

To attempt to assign an origin to philosophy would be ridiculous; for every man endeavours to ascertain the causes of those changes which he observed in nature; and even children themselves are inquisitive after that which produces the sound of their drums and their rattles. Children, therefore, and the most illiterate vulgar, have in all ages been philosophers. But the first people amongst whom philosophy was cultivated as a profession was probably the Chaldeans. We certainly read of none earlier; for although we have more authentic accounts of the Hebrews than of any other nation of remote antiquity, and have reason to believe that no people was civilized before them, yet the peculiar circumstances in which they were placed rendered all philosophical investigation to them useless, and even tended to suppress the very spirit of inquiry. The Egyptians indeed pretended to be the first of nations, and to have spread the blessings of religion and the light of science amongst every other people; but, from the earliest records now extant, there is reason to believe that the Chaldeans were a civilized and powerful nation before the Egyptian monarchy was founded.

Of the Chaldean philosophy much has been said, but very little is known. Astronomy seems to have been their favourite study; and at the era of Alexander's conquest of their country, they boasted that their ancestors had continued their astronomical observations throughout a period of 470,000 years. Extravagant claims to antiquity have been common in all nations.4 Calisthenes, who attended the Macedonian conqueror, was requested by Aristotle to inform himself concerning the origin of science in Chaldea; and upon examining into the grounds of this report, he found that their observations reached no farther backwards than 1903, or 2234 years before the Christian era. Even this is a remote antiquity than Ptolemy allows to their science; for he mentions no Chaldean observations prior to the era of Nabonassar, or 747 years before Christ. That they cultivated something which they called philosophy at a much earlier period than this, cannot be questioned; for Aristotle, on the credit of the most ancient records, speaks of the Chaldean magi as prior to the Egyptian priests, who were certainly men of learning before the time of Moses. For any other science than that of the stars we do not read that the Chaldeans were famous; and this seems to have been cultivated by them merely as the foundation of judicial astrology. Persuading the multitude that all human affairs are influenced by the stars, and professing to be acquainted with the nature and laws of this influence, their wise men pretended to calculate nativities, and to predict good and bad fortune.5 This was the source of idolatry and various superstitions; and whilst the Chaldeans were given up to such puerilities, true science could not be much indebted to their labours. If any credit be due to Plutarch and Vitruvius, who quote Berosus, it was the opinion of the Chaldean wise men that an eclipse of the moon happens when that part of its body which is destitute of fire is turned towards the earth. Their cosmogony, as given by Berosus, and preserved by Syncellus, seems to be this, that all things in the beginning consisted of darkness and water; that a divine power, dividing this humid mass, formed the world; and that the human mind is an emanation from the divine nature.6

The large tract of country which comprehended the empires of Assyria and Chaldea was the first peopled region on earth. From that country, therefore, the rudiments of science must have been propagated in every direction throughout the rest of the world; but what particular people made the earliest figure, after the Chaldeans, in the history of philosophy, cannot be certainly known. The claim of the Egyptians is probably best founded; but as their science

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1 This article, which was written by the late Professor Robson for the third edition of the present work, has, after some slight alterations, been retained, as well on account of the frequent references to it from the article Physics, contributed by the same distinguished author, as on account of the elaborate and somewhat peculiar view which it takes of Lord Bacon's philosophy. On this latter subject, however, the reader will do well to turn to the invaluable commentary upon the Novum Organum, contained in the Second Dissertation prefixed to the present edition.

2 Cicero's Chart and Scale of Truth, vol. i. p. 8.

3 Concerning the partem philosophiam in doctrinam tres: doctrinam de nomine, doctrinam de natura, doctrinam de homine. Quomam autem partitiones scientiarum non sunt unice diversis similes, quae coeunt ad unum angulum, sed potius ramis arborum, qui conjunguntur in uno trunco, qui etiam truncus ad spatium nonnullum integer est et continuus, antequam se partiatur in ramos. (De Aug. Scient. lib. iii. cap. 1.)

4 This claim of the Babylonians is thus rejected with contempt by Cicero: "Contemnamus Babylonios, et eos, qui a Canosio collis signa servantes, numeris, et motibus, stellarum cursus perseguuntur; condemnamus, inquam, hos aut statutis, aut tonsoris, aut imperatoris, qui 470 millia annorum, ut ipsi dicunt, monumentis comprehensa continent, et mentiri judicemus, nec sacrorum religiorum judicia, quod de ipsis futurum sit, perspicere." (De Divinatione, lib. ii. § 19.)

5 Apud Laertium, lib. i. § 8.

6 Sextus Emp. ad Math., lib. iv. § 2; Strabo, lib. c.; Cie. de Div. lib. i. § 1.

7 Enfield's Hist. Phil. vol. i. was the immediate source of that of the Greeks, we shall defer what we have to say of it, on account of the connec- tion between the parent and the offspring, and turn our at- tention from Chaldean to Indian philosophy, as it has been cultivated from a very early period by the Brahmins and Gymnosophists. We pass over Persia, because we know not of any science peculiar to that kingdom except the doc- trines of the magi, which were religious rather than philo- sophical.

From whatever quarter India received its wisdom, we are certain that its philosophers were held in high repute at a period of very remote antiquity, since they were visited by Pythagoras and other sages of ancient Greece, who travel- led in pursuit of knowledge. Yet they seem to have been in that early age, as well as at present, more distinguished for the severity of their manners than for the acquisition of science; and, as Dr Enfield observes, they appear to have more resembled modern monks than ancient philosophers. The Brahmins or Brahmins, it is well known, are all of one tribe; and the most learned of them are in their own lan- guage called Pundits. The Greek writers, however, men- tion a society called Samaneans, who, voluntarily devoting themselves to the study of divine wisdom, gave up all pri- vate property, committing their children to the care of the state, and their wives to the protection of their relations. This society was supported at the public expense; and its members spent their time in contemplation, in conversation on divine subjects, or in acts of religion.

The philosophy of the Indians has indeed from the be- ginning been engrafted upon their religious dogmas, and seems to be a compound of fanatical metaphysics and ex- travagant superstition, without the smallest seasoning of ra- tional physics. Very unlike the philosophers of modern Europe, of whom a great part labour to exclude the agency of mind from the universe, the Pundits of Hindustan allow no powers whatever to matter, but introduce the Supreme Being as the immediate cause of every effect, however tri- vial. "Brahm, the Spirit of God," says one of their most revered Brahmins, "is absorbed in self-contemplation. The same is the mighty lord, who is present in every part of space, whose omnipresence, as expressed in the Reig Beid or Rigveda, I shall now explain. Brahm is one, and to him there is no second; such is truly Brahm. His omniscience is self-inspired or self-intelligent, and its comprehension in- cludes every possible species. To illustrate this as far as I am able, the most comprehensive of all comprehensive fac- ulties is omniscience; and being self-inspired, it is sub- ject to none of the accidents of mortality, conception, birth, growth, decay, or death; neither is it subject to passion or vice. To it the three distinctions of time, past, present, and future, are not. To it the three modes of being are not. It is separated from the universe, and independent of all. This omniscience is named Brahm. By this omni- scient Spirit the operations of God are enlivened. By this Spirit also the twenty-four powers of nature are animated. How is this? As the eye by the sun, as the pot by the fire, as iron by the magnet, as variety of imitations by the mimic, as fire by the fuel, as the shadow by the man, as dust by the wind, as the arrow by the spring of the bow, and as the shade by the tree, so by this Spirit the world is endowed with the powers of intellect, the powers of the will, and the powers of action. Hence, if it emanates from the heart by the channel of the ear, it causes the percep- tion of sound; if it emanates from the heart by the chan- nel of the skin, it causes the perception of touch; if it ema- nates from the heart by the channel of the eye, it causes the perception of visible objects; if it emanates from the heart by the channel of the tongue, it causes the percep- tion of taste; if it emanates from the heart by the channel of the nose, it causes the perception of smell. This also invigorating the five members of action, and invigorating the five members of perception, and invigorating the five elements, and invigorating the five senses, and invigorating the three dispositions of the mind, causes the creation or the annihilation of the universe, whilst itself beholds every thing as an indifferent spectator."

From this passage it is plain that all the motions in the universe, and all the perceptions of man, are, according to the Brahmins, caused by the immediate agency of the Spi- rit of God, which seems to be here considered as the soul of the world. But it appears, from some papers in the Asi- atic Researches, that the most profound of these oriental phi- losophers, and even the authors of their sacred books, be- lieve not in the existence of matter as a separate substance, but hold an opinion respecting it very similar to that of the celebrated Berkeley. The Vedants, says Sir William Jones, unable to form a distinct idea of brute matter in- dependent of mind, or to conceive that the work of Su- preme Goodness was left a moment to itself; imagine that the Deity is ever present to his work, and constantly sup- ports a series of perceptions, which in one sense they call il- lusionary, though they cannot but admit the reality of all creat- ed forms, as far as the happiness of creatures can be affect- ed by them. This is the very immaterialism of Berkeley; and in proof that it is the genuine doctrine of the Brahmins, the learned president quotes the Bhāgavat, which is believ- ed to have been pronounced by the Supreme Being, and in which is the following sentence: "Except the first cause, whatever may appear, and may not appear, in the mind, know that to be the mind's Māya, or delusion, as light, as darkness."

We have shown elsewhere (see Metaphysics), that the metaphysical doctrines of the Brahmins respecting the hu- man soul differ not from those of Pythagoras and Plato; and that they believe it to be an emanation from the great soul of the world, which, after many transmigrations, will be finally absorbed in its parent substance. In proof of their believing in the metempsychosis, Mr Hallhed gives us the following translation of what, he says, is a beautiful stanza in the Gētā: "As, throwing aside his old clothes, a man puts on others that are new; so our lives, quitting the old, go to other newer animals."

From the Brahmins believing in the soul of the world not Physics only as the sole agent, but as the immediate cause of every and astro- motion in nature, we can hardly suppose them to have made any great progress in that science which in Europe is cul- tivated under the name of Physics. They have no induc- ment to investigate the laws of nature, because, according to the first principles of their philosophy, which, together with their religion, they believe to have been revealed from heaven, every phenomenon, however regular, or however anomalous, is produced by the voluntary act of an intelli- gent mind. Yet if they were acquainted with the use of fire-arms four thousand years ago, as Mr Hallhed seems to

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1 To be awake, to sleep, and to be absorbed in a state of unconsciousness, that is, in a kind of trance. 2 The twenty-four powers of nature, according to the Brahmins, are the five elements, fire, air, earth, water, and aksh (a kind of subtle ether); the five members of action, the hand, feet, tongue, anus, and male organ of generation; the five organs of perception, the ear, eye, nose, mouth, and skin; the five senses, which they distinguish from the organs of sensation; the three dispositions of the mind, desire, passion, and tranquillity; and the power of consciousness. 3 If the work from which this extract is quoted be of as great antiquity as Mr Halhed supposes, the Brahmins must have been acquaint- ed with the phenomena of magnetism at a much earlier period than any other philosophers of whom history makes mention. 4 Preliminary Dissertation to Hallhed's Gentoo Laws. believe, he who made that discovery must have had a very considerable knowledge of the powers of nature; for though gunpowder may have been discovered by accident in the East, as it certainly was in the West many ages afterwards, it is difficult to conceive how mere accident could have led any man to the invention of a gun. In astronomy, geometry, and chronology, too, they appear to have made some proficiency at a very early period. Their chronology and astronomy are indeed full of those extravagant fictions which seem to be essential to all their systems; but their calculation of eclipses, and their computations of time, are conducted upon scientific principles.

"It is sufficiently known," says Mr Davis,1 "that the Hindu division of the ecliptic into signs, degrees, &c. is the same as ours; that their astronomical year is sidereal, or containing that space of time in which the sun, departing from a star, returns to the same; that it commences on the instant of his entering the sign Aries, or rather the Hindu constellation Mēsha; that each astronomical month contains as many even days and fractional parts as he stays in each sign; and that the civil differs from the astronomical account of time only in rejecting those fractions, and beginning the year and month at sunrise, instead of the intermediate instant of the artificial day or night. Hence arises the unequal portion of time assigned to each month, dependent on the situation of the sun's apsis, and the distance of the vernal equinoctial colure from the beginning of Mēsha in the Hindu sphere; and by these means they avoid those errors which Europeans, from a different method of adjusting their calendar by intercalary days, have been subject to."

Mr Davis observes, that an explanation of these matters would have led him beyond his purpose, which was only to give a general account of the method by which the Hindus compute eclipses, and to show that the science of astronomy is as well known amongst them now as ever it was amongst their ancestors. This he does very completely; but in the present short historical sketch we can neither copy nor abridge his memoir. Suffice it to say, that he has shown the practical part of the Hindu astronomy to be founded on mathematical principles; and that the learned Pundits appear to have truer notions of the form of the earth and the economy of the universe than those which are ascribed to their countrymen in general.

The same writer likewise shows, that the prodigious duration which the Hindus attribute to the world, is the result of a scientific calculation, founded indeed upon very whimsical principles. "It has been common with astronomers to fix on some epoch, from which, as from a radix, to compute the planetary motions; and the ancient Hindus chose that point of time counted back, when, according to their motions as they had determined them, they must have been in conjunction in the beginning of Mēsha or Aries, and coeval with which circumstance they supposed the creation. This, as it concerned the planets only, would have produced a moderate term of years compared with the enormous antiquity that will be hereafter stated; but having discovered a slow motion of the nodes and apsides also, and taken it into computation, they found it would require a length of time corresponding with 1,955,884,890 years, now expired, when they were so situated, and 2,364,115,110 years more before they would return to the same situation again, forming together the grand anomalistic period denominated a Calpa, and fancifully assigned as the day of Brahma."

But although the mathematical part of the astronomy of the Pundits is undoubtedly respectable, their physical notions of the universe are in the highest degree ridiculous and extravagant. In the Vedas and Puranas, writings of which no devout Hindu can dispute the divine authority, eclipses are said to be occasioned by the intervention of the monster Rahu, and the earth to be supported by a series of animals. "They suppose," says Mr Halliday, "that there are fourteen spheres, seven below and six above the earth. The seven inferior worlds are said to be altogether inhabited by an infinite variety of serpents, described in every monstrous figure that the imagination can suggest. The first sphere above the earth is the immediate vault of the visible heavens, in which the sun, moon, and stars are placed. The second is the first paradise, and genera, receptacle of those who merit a removal from the lower earth. The third and fourth are inhabited by the souls of those men who, by the practice of virtue and dint of prayer, have acquired an extraordinary degree of sanctity. The fifth is the reward of those who have all their lives performed some wonderful act of penance and mortification, or who have died martyrs for their religion. The highest sphere is the residence of Brahma and his particular favourites, such as those men who have never uttered a falsehood during their whole lives, and those women who have voluntarily burned themselves with their husbands. All these are absorbed in the divine essence."

On ethics, the Hindus have nothing that can be called philosophy. Their duties, moral, civil, and religious, are all laid down in their Vedas and Shasters, and enjoined by what they believe to be divine authority, which supersedes all reasoning concerning their fitness or utility. The business of their Pundits is to interpret these books, which are extremely ancient, and written in a language that has long been unintelligible to every other order of men; but no Pundit will alter the text, however impossible to be reconciled to principles established in his own practice of astronomy. On such occasions, the usual apology for their sacred books is, that "such things may have been so formerly, and may be so still; but that for astronomical purposes astronomical rules must be followed." The great duties of morality have been prescribed in every religious code; and they are not overlooked in that of the Hindus, although the highest merit that a Brahmin can have consists in voluntary acts of abstinence and mortification, and in contempt of death.

Of the ancient philosophy of the Arabians and Chinese nothing certain can be said; and the narrow limits of such an abstract as this do not admit of our mentioning the conjectures of the learned, which contradict each other, and are all equally groundless. There is indeed sufficient evidence that both nations were at a very early period observers of the stars, and that the Chinese had even a theory by which they foretold eclipses; but there is reason to believe that the Arabians, like other people in their circumstances, were nothing more than judicial astrologers, who possessed not the smallest portion of astronomical science. Pliny makes mention of their magi, whilst later writers tell us that they were famous for their ingenuity in solving enigmatical questions, and for their skill in the arts of divination. But the authors of Greece are silent concerning their philosophy; and there is not an Arabian book of greater antiquity than the Koran extant.

Leaving therefore regions so barren of information, let us pass to the Phoenicians, whose commercial celebrity has once induced many learned men to allow them great credit for their early science. If it be true, as seems highly probable, that the ships of this nation had doubled the Cape and almost encompassed the peninsula of Africa long before the era of Solomon, we cannot doubt that the Phoenicians had made great proficiency in the art of navigation and in the science of astronomy at a period of very remote antiquity. Nor were these the only sciences cultivated by that ancient people. The learned Cudworth has, in our opinion, sufficiently proved that Moschus or Mochus, a Phenician, who, according to Strabo, flourished before the Trojan war, was the author of the atomic philosophy afterwards adopted by Leucippus, Democritus, and others, amongst the Greeks; and that it was with some of the successors of this sage that, as Jamblichus tells us, Pythagoras conversed at Sidon, and from them received his doctrine of monads. Another proof of the early progress of the Phenicians in philosophy may be found in the fragments of their historian Sanchoniathon, which have been preserved by Eusebius. We are indeed aware that men of great celebrity have called in question the authenticity of those fragments, and even the very existence of such a writer as Sanchoniathon; but for this skepticism we can discover no solid foundation. His history may have been interpolated in some places by the translator Philo-Byblius; but Porphyry, Eusebius, and Theodoret, speak of it as a work of undoubted credit, and affirm that its author flourished before the Trojan war. Now this ancient writer teaches, that, according to the wise men of his country, all things arose at first from the necessary agency of an active principle upon a passive chaotic mass, which he calls mot. This chaos, Cudworth thinks, was the same with the elementary water of Thales, who was also of Phenician extraction; but Mosheim justly observes that it was rather dark air, since Philo translates it ἀέρα σκοτεινόν. Be this as it may, nothing can be more evident than that the Phenicians must have made some progress in what must surely be considered as philosophy, however false, as early as the era of Sanchoniathon; for speculations concerning the origin of the world never occur to untaught barbarians. Besides Mochus and Sanchoniathon, Cadmus, who introduced letters into Greece, may undoubtedly be reckoned amongst the Phenician philosophers; for though it is not pretended that the alphabet was of his invention, and though it is by no means certain that the Greeks, at the time of his arrival amongst them, were wholly destitute of alphabetic characters; yet the man who could prevail with illiterate savages to adopt the use of strange characters, must have been a great master of the science of human nature. Several other Phenician philosophers are mentioned by Strabo; but as they flourished at a later period, and philosophized after the systematic mode of the Greeks, they do not fall properly under our notice. We pass on therefore to the philosophy of Egypt.

It has already been observed that the Egyptians boasted of being the first of nations, and the authors of all the science which in separate rays illuminated the rest of the world. But though this claim was undoubtedly ill founded, their high antiquity and early progress in the arts of civil life cannot be controverted. The Greeks with one voice confess that all their learning and wisdom came from Egypt, either imported immediately by their own philosophers, or brought through Phenicia by the sages of the East; and we know, from higher authority than the histories of Greece, that at a period so remote as the birth of Moses the wisdom of the Egyptians was proverbially famous. Yet the history of Egyptian learning and philosophy, although men of the first eminence, both ancient and modern, have bestowed much pains in attempts to elucidate it, still remains involved in clouds of uncertainty. That they had some knowledge of physiology, arithmetic, geometry, and astronomy, are facts which cannot be questioned; but there is reason to believe that even these sciences were in Egypt History pushed no farther than to the uses of life. That they believed in the existence of incorporeal substances is certain; because Herodotus assures us that they were the first assertors of the immortality, pre-existence, and transmigration of human souls, which they could not have been without holding those souls to be at least incorporeal, if not immaterial.

The founder of Egyptian learning is generally acknowledged to have been Thoth, Theut, or Taaut, called by the Greeks Hermes, and by the Romans Mercury; but of this personage very little is known. Diodorus Siculus says that he was chief minister to Osiris, and that he improved language, invented letters, instituted religious rites, and taught astronomy, music, and other arts. The same thing is affirmed by Sanchoniathon, whose antiquity has already been mentioned; by Manetho, an Egyptian priest, who flourished during the reign of Ptolemy Philadelphus; and by Plato, whose authority, as he resided long in Egypt, and was himself an eminent philosopher, is perhaps more to be depended upon than that of the other two. In the Philicus we are told that Thoth was the inventor of letters; and lest we should suppose that by these letters nothing more is meant than picture-writing or symbolical hieroglyphics, it is added, that he distinguished between vowels and consonants, determining the number of each. The same philosopher, in his Phaedrus, attributes to Thoth the invention of arithmetic, geometry, astronomy, and hieroglyphical learning; and subjoins a disputatious said to have been held between him and Thamus, then king of Egypt, concerning the advantage and disadvantage of his newly-invented letters. Thoth boasted that the invention, by aiding memory, would greatly contribute to the progress of science; whilst the monarch contended that it would enervate men's natural faculties, by making them trust to written characters, without exerting the powers of their own minds.

All this, if real, must have happened before the era of Moses; and since it is almost certain that alphabetical characters were in use prior to the exod of the Israelites from Egypt, we may as well allow the invention to Thoth, as give it to an earlier author of unknown name. That arithmetic, geometry, and astronomy, were cultivated in Egypt from the most remote antiquity, is affirmed by all the ancients, and rendered in the highest degree probable by the situation of the country. The first elements of astronomy have certainly been discovered by various nations, whose habits of life led them to the frequent observation of the heavens; and it is observed by Cicero, that the Egyptians and Babylonians, dwelling in open plains, where nothing intercepted the view of the heavenly bodies, naturally devoted themselves to the study of that science. The annual overflowing of the Nile, which broke up the boundaries of their land, would lay the Egyptians under the necessity of adopting some method of settling those boundaries anew; and necessity we know to be the parent of invention. Hence their early acquaintance with practical geometry cannot well be doubted. Their custom of embalming their dead, and the perfection to which they carried that art, shows infallibly their knowledge of the properties of natural substances, and gives some reason to believe that they were not altogether strangers to anatomy; but if we allow them to have been at this early period anatomists acquainted with the power of drugs, we can hardly refuse them some skill in the art of physic, which they themselves traced up to their

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1 *Preparatus Evangelii.* 2 It is true that the dissection of some mummies has lessened the high opinion long entertained of the skill of the ancient Egyptians in the art of embalming; yet it must be granted that their knowledge of antiseptic drugs was great, since it is now certainly known, even from these dissections, that by means of such drugs they contrived to preserve rags of cloth from corruption for upwards of three thousand years. The art of alchemy has been said to have been known by the ancient Egyptians; and, from the author of the Egyptian philosophy, it has been called the Hermetic art. But although this is unquestionably a fiction, there is evidence that they were possessed of one art which is even yet a desideratum in the practice of chemistry. "Moses," we are told, "took the golden calf which his brother had made for idolatrous purposes, and burnt it in the fire, and ground it to powder, and strewed it on the water, and made the children of Israel drink of it." Had this fact been related by Herodotus or Diodorus Siculus, it would have been deemed sufficient evidence that the Egyptians were even at that early period no strangers to the art of chemistry; and surely the evidence should not be the worse for coming from the pen of the Hebrew lawgiver, who was himself educated in the court of Egypt.

But although it is thus evident that the rudiments of almost every useful science were known in Egypt from the remotest antiquity, it does not appear that any of them was carried to a great degree of perfection, unless perhaps chemistry alone must be excepted. One would think that no science could have been more indispensably requisite to them than geometry; and yet, though Pythagoras is said to have spent twenty-two years in Egypt studying that science and astronomy, he himself discovered the famous forty-seventh proposition of Euclid's first book after his return to Samos. This, although a very useful, is yet a simple theorem; and since it was not reached by the Egyptian geometry, we cannot suppose that the people of Egypt had then advanced far in such speculations. The same conclusion must be drawn with respect to astronomy; for Thales is said to have been the first who calculated an eclipse of the sun, and we nowhere read that the Egyptians pretended to dispute that honour with him. To this it may be replied, that Pythagoras was in Egypt undoubtedly taught the true constitution of the solar system, and, what is more extraordinary, the doctrine of comets in particular, and of their revolutions, like the other planets, round the sun. We grant that he was taught all this; but it was not scientifically, but dogmatically, as facts which the priests had received by tradition from their early ancestors, and of which they had never questioned the truth nor inquired into the reasons. Of this we need no better proof than that the Pythagorean system of the sun was totally neglected by the Greeks as soon as they began to frame hypotheses and to speculate in philosophy.

But it may appear strange, and certainly is so, that the Egyptian priests, in the days of Pythagoras, should have preserved so great a discovery of their ancestors, and at the same time have totally forgotten the principles and reasoning which led to a conclusion apparently contrary to the evidence of sense. This is a difficulty which we pretend not to remove, although the fact which involves it seems to be beyond the reach of controversy. Perhaps the following observations may throw upon it a feeble light. According to Manetho, the written monuments of the first Thoth were lost or neglected in certain civil revolutions or natural calamities which befell the kingdom of Egypt. After many ages great part of them were recovered by an ingenious interpretation of the symbols which he had inscribed upon ancient columns; and the man who made this interpretation was called the second Thoth, or Hermes Trismegistus. But thrice illustrious as this personage was, it is at least possible that he may have been much inferior to the former Hermes, and have read his writings and transcribed his conclusions without being able to comprehend the principles or reasoning which led to these conclusions. Any man who understands Latin might translate into his own tongue the conclusions of Newton; but much more would be requisite to make him comprehend the demonstrations of his sublime geometry. By what mode of reasoning the first Hermes was led to the true idea of the solar system, or whether it was by reasoning at all, cannot now be known; but it seems very evident, that when the intercourse between the Egyptians and Greeks first commenced, the wisdom of the former people consisted chiefly in the science of legislation and civil policy, and that the philosopher, the divine, the legislator, and the poet, were all united in the same person. Their cosmogony (for all the ancients who pretended to science framed cosmogonies) differed little from that of the Phoenicians already mentioned. They held that the world was produced from chaos by the energy of an intelligent principle; and they likewise conceived that there is in nature a continual tendency towards dissolution. In Plato's Timaeus, an Egyptian priest is introduced describing the destruction of the world, and asserting that this will be effected by means of water and fire. They conceived that the universe undergoes a periodical conflagration; after which all things are restored to their original form, to pass again through a similar succession of changes.

Of preceptive doctrine the Egyptians had two kinds, the one sacred, the other vulgar. The former, which respected the ceremonies of religion and the duties of the priests, was doubtless written in the sacred books of Hermes, but was too carefully concealed to pass down to posterity. The latter consisted of maxims and rules of virtue, prudence, or policy. Diodorus Siculus relates many particulars concerning the laws, customs, and manners of the Egyptians; whence it appears that superstition mingled with and corrupted their notions of morals. It is in vain to look for accurate principles of ethics among an ignorant and superstitious people. And that the ancient Egyptians merited this character is sufficiently evident from this single circumstance, that they suffered themselves to be deceived by

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1 Exodus, xxii. 20. 2 This discovery he claimed; and his claim was admitted by the Greek writers, without having been directly controverted since. An excellent mathematician, however, has shown that the equality between the square of the hypothenuse of a right-angled triangle, and the sum of the squares on the other two sides, was known to the astronomers of India at a period long prior to that of Pythagoras. Notwithstanding this, it is certainly possible that the sage of Samos may have made the discovery himself, though we think the contrary much more probable; for we agree with the able writer already mentioned, that Pythagoras, who is generally believed to have conversed with Indian Brahmins as well as Egyptian priests, may have derived from them some of the solid as well as the visionary speculations with which he delighted to instruct or amuse his disciples. See Transactions of the Royal Society of Edinburgh, vol. ii. 3 This is recorded by Aristotle and Plutarch, and thus expressed by Ammianus Marcellinus: "Stellas quasdam, ceteras similes, quarum orbitas orbituque, quibus sint territoriis praediti humannis mentibus ignoranti (lib. xxv. cap. 10)." 4 Fixar in supremis mundi partibus immotas persisteret, et planetas his inferiores circa solis revolvi, terram pariter moveri curru annuo, diurno vero circa axem proprium, et solem eum facere universi in omnibus centuris sequente, antiquissima fuit philosophantium sententia. Ab Ægyptis autem astrorum antiquissimis observantibus propugnatur esse hanc sententiam verissime est. Et etiam ab illis etiam gentibus Graecis ad Graecos, et ad Philolochos, et ad philosophos philosophos, philosophia omnium antiquior juxta et senior maxime videtur. Subinde docuerunt Anaxagoras, Democritus, et ali nulli, terram in centro mundi immotam stare, et astra omnium in occasum et aliquid celerrimis, alla tardius moveri, idoque in spatii liberissimi. Namque orbis solidi postea ab Eudoxo, Calippo, Aristotele, introducti sunt; declinante indies philosophia primitus introducta, et novis Graecorum commentis paulatim prevalentibus. Quibus recens antiqui planetas in spatii liberis retineri, deque cursu rectilineo perpetuo retractas in orbem regulariter agi docere, non constat. (Newton de Mundi Systemate.) impostors, particularly by the professors of the fanciful art of astrology; concerning whom Sextus Empiricus justly remarks, that they have done much mischief in the world, by enslaving men to superstition, which will not suffer them to follow the dictates of right reason."

From Egypt and Phoenicia philosophy passed into Greece, where it was long taught without system, as in the countries from which it was derived. Phoroneus, Cecrops, Cadmus, and Orpheus, were amongst the earliest instructors of the Greeks; and they inculcated Egyptian and Phoenician doctrines in detached maxims, and enforced them, not by strength of argument, but by the authority of tradition. Their cosmogonies were wholly Phoenician or Egyptian disguised under Grecian names; and they taught a future state of rewards and punishments. The planets and the moon Orpheus conceived to be habitable worlds, and the stars to be fiery bodies like the sun; but he taught that they are all animated by divinities, an opinion which prevailed both in Egypt and in the East. It does not appear, however, that he gave any other proof of his doctrines than a confident assertion that they were derived from some god.

Hitherto we have seen philosophy in its state of infancy and childhood, consisting only of a collection of sententious maxims and traditional opinions; but amongst the Greeks, an ingenious and penetrating people, it soon assumed the form of profound speculation and systematic reasoning. Two eminent philosophers arose nearly at the same period, who may be considered as the parents not only of Grecian science, but of almost all the science which was cultivated in Europe prior to the era of the great Lord Bacon. These were Thales and Pythagoras, of whom the former founded the Ionic school, and the latter the Italic; from which two sprang the various sects into which the Greek philosophers were afterwards divided. A bare enumeration of these sects is all that our limits will admit of; and we shall give it in the perspicuous language and just arrangement of Dr Enfield, referring our readers for a fuller account than we can give of their respective merits to his abridged translation of Brucker's history.

From the Ionic School sprung various others: 1. The Ionic sect proper, whose founder Thales had as his successors Anaximenes, Anaxagoras, Diogenes Apolloniates, and Archelaus. 2. The Socratic school, founded by Socrates, the principal of whose disciples were Xenophon, Alcibiades, Critias, Cebes, Aristippus, Phaedo, Euclid, Plato, Antisthenes, Critias, and Alcibiades. 3. The Cyrenaic sect, of which Aris- tippus was the author; his followers were, his daughter Arete, Hegesias, Anicerris, Theodorus, and Bion. 4. The Megaric or Eristic sect, formed by Euclid of Megara; to whom succeeded Eubulides, Diodorus, and Stilpo, famous for their logical subtlety. 5. The Eliac or Eretriac school, raised by Phaedo of Elis, who, although he closely adhered to the doctrine of Socrates, gave name to his school. His successors were Plataanus and Menedemus; the latter of whom, being a native of Eretria, transferred the school and name to his own country. 6. The Academic sect, of which Plato was the founder. After his death, many of his disciples deviating from his doctrine, the school was divided into the old, new, and middle academies. 7. The Peripatetic sect, founded by Aristotle, whose successors in the Lyceum were Theophrastus, Strato, Lycon, Aristo, Critolaus, and Diodorus. Amongst the Peripatetics, besides those who occupied the chair, were also Dioclesarchus, Endemus, and Demetrius Phalereus. 8. The Cynic sect, of which the author was Antisthenes, whom Diogenes, Onesicritus, Crates, Metrocles, Menippus, and Menédemus, succeeded. In the list of Cynic philosophers must also be reckoned Hipparchia, the wife of Crates. 9. The Stoic sect, of which Zeno was the founder. His successors in the porch were Perseus, Aristo of Chios, Herillus, Sphaerius, Cleanthus, Chrysippus, Zeno of Tarsus, Diogenes the Babylonian, Antipater, Panetius, and Posidonius.

Of the Italic School were, 1. The Italic sect proper, founded by Pythagoras, a disciple of Pherecydes. The followers of Pythagoras were Aristaeus, Mnesarchus, Alcmaeon, Ephantius, Hippo, Empedocles, Epicharmus, Ocellus, Timaeus, Archytas, Hippasus, Philolaus, and Eudoxus. 2. The Eleatic sect, of which Xenophanes was the author. His successors, Parmenides, Melissus, Zeno, belonged to the metaphysical class of this sect; Leucippus, Democritus, Protagoras, Diagoras, and Anaxarchus, to the physical. 3. The Heraclitean sect, which was founded by Heraclitus, and soon afterwards expired. Zeno and Hippocrates philosophized after the manner of Heraclitus, and other philosophers borrowed freely from his system. 4. The Epicurean sect, a branch of the Eleatic, had Epicurus for its author; and amongst his followers were Metrodorus, Polyenus, Hermachus, Polyastratus, Basilides, and Protarchus. 5. The Pyrrhonic or Sceptical sect, the parent of which was Pyrrho. His doctrine was taught by Timon the Phliasian; and after some interval was continued by Ptolemy, a Cyrenean, and at Alexandria by Ænesidemus.

Of the peculiar doctrines of these sects, the reader will in this work find a short account either in the lives of their respective founders, or under the names of the sects themselves. We shall only observe at present, that although many of them were undoubtedly absurd, and many wicked, it would yet perhaps be going too far to say with some, that the philosophy of Greece became impious under Diagoras, vicious under Epicurus, hypocritical under Zeno, impudent under Diogenes, covetous under Demochares, voluptuous under Metrodorus, fantastical under Crates, scurrilous under Menippus, licentious under Pyrrho, and quarrelsome under Cleanthus. Of the truth of this heavy charge every reader must judge for himself. We are strongly inclined to think that there were virtues and vices peculiar to each sect; "and that the sects themselves had an affinity more or less direct with the different temperaments of man; whence the choice of sectators often depended on physical influence, or a peculiar disposition of their organs." Nothing appears more natural than that those men who were born with great force of mind and strong nerves should discover a predilection for stoicism; while mortals endowed by nature with more delicacy of fibres and keener sensibility fled for refuge to the myrtles of Epicurus. People whose temperaments partook of no extremes, were always inclined either for the Lyceum or the Academy. Such as possessed solidity of understanding ranged themselves with Aristotle; and those who had only genius, or even pretensions to that endowment, went to augment the crowd of Platonists.

All the systematical philosophers, however, pursued their Grecian inquiries into nature by nearly the same method. Of their mode of philosophy, as well as of ours, the universe, with all that it contains, was the vast object; but the individual things which compose the universe are infinite in number and ever changing; and therefore, according to an established maxim of theirs, incapable of being the subjects of human science. To reduce this infinitude, and to fix those fleeting beings, they established certain definite arrangements or classes, to some of which every thing past, present, or to come, might be referred; and having ascertained, as they thought, all that could be affirmed or denied of these classes, they proved, by a very short process of syllogistic reasoning, that what is true of the class must be true of every individual com-

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1 Pauw's Philosophical Dissertation. 2 Boethius in Prædict. et Arist. Physic. lib. i. prehended under it. The most celebrated of these arrangements is that which is known by the name of categories, which Mr Harris thinks at least as old as the era of Pythagoras, and to the forming of which mankind would, in his opinion, be necessarily led by the following considerations. Every subject of human thought is either substance or attribute; but substance and attribute may each of them be modified under the different characters of universal or particular. Hence there arises a quadruple arrangement of things into substance universal and substance particular, into attribute universal and attribute particular; to some one of which four not only our words and ideas, but every individual of that immense multitude of things which compose the universe, may be reduced. This arrangement, however, the learned author thinks too limited; and he is of opinion, that, by attending to the substances with which they were surrounded, the Grecian schools must soon have distinguished between the attributes essential to all substances, and those which are only circumstantial; between the attributes proper to natural substances or bodies, and those which are peculiar to intelligible substances or minds. He likewise thinks, that the time and place of the existence of substances not present must soon have attracted their attention; and that, in considering the place of this or that substance, they could hardly avoid thinking of its position or situation. He is of opinion that the superinduction of one substance upon another would inevitably suggest the idea of clothing or habit, and that the variety of co-existing substances and attributes would discover to them another attribute, viz. that of relation. Instead, therefore, of confining themselves to the simple division of substance and attribute, they divided attribute itself into nine distinct sorts, some essential and others circumstantial; and thus, by setting substance at their head, made ten comprehensive universal genera, called, with reference to their Greek name, categories, and with reference to their Latin name, predicaments. These categories are, Substance, Quality, Quantity, Relation, Action, Passion, When, Where, Situation, and Clothing; which, according to the systematic philosophy of the Greeks, comprehend every human science and every subject of human thought. History, natural and civil, springs, says Mr Harris, out of Substance; mathematics out of Quantity; optics out of Quality and Quantity; medicine out of the same; astronomy out of Quantity and Motion; music and mechanics out of the same; painting out of Quality and Site; ethics out of Relation; chronology out of When; geography out of Where; electricity, magnetism, and attraction, out of Action and Passion; and so in other instances.

To these categories, considered as a mere arrangement of science, we are not inclined to make many objections. The arrangement is certainly not complete; but this is a matter of comparatively small importance, for a complete arrangement of science cannot, we believe, be formed. The greatest objection to the categories arises from the use which was made of them by almost every philosopher of the Grecian schools; for those sages having reduced the objects of all human science to ten general heads or general terms, instead of setting themselves to inquire, by a painful induction, into the nature and properties of the real objects before them, employed their time in conceiving what could be predicated of substance in general, of this or that quality, quantity, relation, &c., in the abstract; and they soon found, that of such general conceptions as the categories there are but five predicables or classes of predicates in nature. The first class is that in which the predicate is the genus of the subject; the second, that in which it is the species of the subject; the third is, when the predicate is the specific difference of the subject; the fourth, when it is a property of the subject; and the fifth, when it is something accidental to the subject. Having proceeded thus far in their system, they had nothing to do with individuals but to arrange them under their proper categories, which was commonly done in a very arbitrary manner; and then, with the formality of a syllogism, to predicate of each the predicable of the genus or species to which it belonged. But by this method of proceeding, it is obvious that no progress whatever could be made in physical, metaphysical, or ethical science; for if the individual truly belongs to the category under which it is arranged, we add nothing to our stock of knowledge by affirming or denying of it what we had before affirmed or denied of the whole genus; and if it belong not to the category under which we arrange it, our syllogising will only give the appearance of proof to what must, from the nature of things, be an absolute falsehood. It is only by experiments made on various substances apparently of the same kind that they can be certainly known to belong to the same category; and when this is done, all syllogistic reasoning, from the genus to the species, and from the species to the individual, is but solemn trifling, as every proposition in this retrograde course takes for granted the thing to be proved.

Yet this mode of philosophizing spread from Greece almost over the whole world. It was carried by Alexander into Asia, by his successors into Egypt, and it found its way to Rome after Greece became a province of the empire. It was adopted by the Jews, by the fathers of the Christian church, by the Mahomedan Arabs during the caliphate, and continued to be cultivated by the schoolmen throughout all Europe till its futility was exposed by Lord Bacon. The professors of this philosophy often displayed great acuteness; but their systems were built upon mere hypotheses, and supported by syllogistic wrangling. Now and then indeed a superior genius, such as Alhazen, and our countryman Roger Bacon, broke through the trammels of the schools, and, regardless of the authority of the Stagyrite and his categories, made real discoveries in physical science by experiments judiciously conducted on individual substances; but the science in repute still continued to be that of generals. It was indeed a combination of absurd metaphysics with more absurd theology; and that which is properly called physics had in Europe no place in a liberal education from the end of the eighth century to the end of the fourteenth. Towards the beginning of this period of darkness, the whole circle of instruction, or the liberal arts as they were called, consisted of two branches, the trivium and the quadrivium; the former of which comprehended grammar, rhetoric, and dialectics; the latter music, arithmetic, geometry, and astronomy, to which was added, about the end of the eleventh century, the study of a number of metaphysical subtleties equally useless and unintelligible.

Hitherto the works of the ancient Greek philosophers had been read only in imperfect Latin translations; and before the scholastic system was completely established, Plato and Aristotle had been alternately looked up to as an oracle in science. The rigid schoolmen, however, universally gave the preference to the Stagyrite, because his analysis of body into matter and form is peculiarly calculated to keep in countenance the most incredible doctrine of the Roman Catholic church; and upon the revival of Greek learning this preference was continued after the school philosophy had begun to fall into contempt, on account of much useful information contained in some of his writings on subjects of natural history, and his supposed merit as a natural philosopher. At last the intrepid spirit of Luther and his associates set the minds of men free from the tyranny of ancient names, as well in human science as in theology; and many philosophers sprung up in different countries of Europe, who professed either to be eclectics, or to study nature, regardless of every authority except that of reason. Of these the most eminent beyond all comparison was Francis Bacon, Lord Verulam. This illustrious man having read with attention the writings of the most celebrated ancients, and made himself master of the sciences which were then cultivated, soon discovered the absurdity of pretending to account for the phenomena of nature by syllogistic reasoning from hypothetical principles; and, with a boldness becoming a genius of the first order, he undertook to give a new chart of human knowledge. This he did in his two admirable works, entitled *De Dignitate et Augmentis Scientiarum*; and *Novum Organum Scientiarum, sive Judicia vera de Interpretatione Nature*. In the former of these works, he takes a very minute survey of the whole circle of human science, which he divides into three great branches; history, poetry, and philosophy, corresponding to the three faculties of the mind, memory, imagination, and reason. Each of these general heads is subdivided into minuter branches, and reflections are made upon the whole, which, though we can neither copy nor abridge them, will amply reward the perusal of the attentive reader. The purpose of the *Novum Organum* is to point out the proper method of interpreting nature, which the author shows could never be done by the logic which was then in fashion, but only by a painful and fair induction. "Homo naturae minister," says he, "et interpres tantum facit et intelligit, quantum de naturae ordine re, vel mente observaverit; nec amplius securi aut potest. Syllogismus ad principia scientiarum non adhibetur, ad media axiomata frustra adhibetur, cum sit subtilitati nature longe impar. Assensum itaque constringit, non res. Syllogismus ex propositionibus constat, propositiones ex verbis, verba notionum tesserae sunt. Itaque si notiones ipse (id quod basis est) confuse sint et temere a rebus abstracta, nihil in illo qua superstruuntur, est firmitudinis. Itaque spes est una in *inductione vera*."

To hypotheses and preconceived opinions, which he calls *ideae theatri*, this great man was not less inimical than to syllogisms; and since his days almost every philosopher of eminence, except Descartes and his followers, has professed to study nature according to the method of induction so accurately laid down in the *Novum Organum*. On this method a few improvements have perhaps been made; but notwithstanding these, Lord Bacon must undoubtedly be considered as the author of that philosophy which is now cultivated in Europe, and which will continue to be cultivated as long as men shall have more regard for matters of fact than for hypothetical opinions. Of this mode of philosophizing we shall now give a short, though we hope not inaccurate view, by stating its objects, comparing it with that which it superseded, explaining its rules, and pointing out its uses; and from this view it will appear that its author shares with Aristotle the empire of science.

The universe, that unbounded object of the contemplation, the curiosity, and the researches of man, may be considered in two different points of view. In the first place, it may be considered merely as a collection of existences, related to each other by means of resemblances and distinction, situation, succession, and derivation, as making parts of a whole. In this view it is the subject of pure description. To acquire an acquaintance with, or a knowledge of, the universe in this point of view, we must enumerate all the beings in it, mention all their sensible qualities, and mark all these relations for each. But this would be labour immense; and when done, an undistinguishable chaos. A book containing every word of a language would only give us the materials, so to speak, of this language. To make it comprehensible, it must be put into some form, which will comprehend the whole in a small compass, and enable the mind to pass easily from one word to another related to it. Of all relations amongst words, the most obvious are those of resemblance and derivation. An etymological dictionary, therefore, in which words have been classified in consequence of their resemblances, and arranged by means of their derivative distinctions, will greatly facilitate the acquisition of the language.

It is just so in nature. The objects around us may be grouped by means of their resemblance, and then arranged in those groups by means of their distinctions and other relations. In this classification we are enabled to proceed by means of the faculty of abstracting our attention from the circumstances in which things differ, and turning it to those only in which they agree. By the judicious employment of this faculty we are able not only to distribute the individuals into classes, but also to distribute those classes into others still more comprehensive, by discovering circumstances of resemblance amongst them; for the fewer the circumstances are which concur to form that resemblance which has engaged our attention, the greater is the number of similar circumstances which are neglected, and the more extensive will be the class of individuals in which the resemblance is observed. Thus a number of individuals resembling each other in the single circumstance of life composes the most extensive kingdom of Animals. If it be required that they shall further resemble in the circumstance of having feathers, a prodigious number of animals are excluded, and we form the inferior class of Birds. We exclude a great number of birds by requiring a further similarity of web feet, and have the order of Anseres. If we add lingua ciliata, we confine the attention to the genus of Anatæs. In this manner may the whole objects of the universe be grouped, and arranged into kingdoms, classes, orders, genera, and species.

Such a classification and arrangement is called *Natural History*, and must be considered as the only foundation of any extensive knowledge of nature. To the natural historian, therefore, the world is a collection of existences, the subject of descriptive arrangement. His aim is threefold. 1. To observe with care, and describe with accuracy, the various objects of the universe. 2. To determine and enumerate all the great classes of objects; to distribute and arrange them into all their subordinate classes, through all degrees of subordination, till he arrive at what are only accidental varieties, which are susceptible of no farther distribution; and to mark with precision the principles of this distribution and arrangement, and the characteristics of the various assemblages. 3. To determine with certainty the particular group to which any proposed individual belongs. Description, therefore, arrangement, and reference, constitute the whole of his employment; and in this consists all his science.

Did the universe continue unchanged, this would constitute the whole of our knowledge of nature; but we are witnesses of an uninterrupted succession of changes, and our attention is continually called to the events which are incessantly happening around us. These form a set of objects vastly more interesting to us than the former, being the sources of almost all the pleasures or pains we receive from external objects. We are therefore much interested in the study of the events which happen around us, and strongly incited to prosecute it. But they are so numerous and so multifarious, that the study would be immense, without some contrivance for abbreviating and facilitating the task. The same help offers itself here as in the study of what may be called *quiescent nature*. Events, like existences, are susceptible of classification, in consequence of resemblances and distinction; and by attention to these, we can acquire a very extensive acquaintance with active nature. Our attention must be chiefly directed to those circumstances in which many events resemble each other, whilst they differ perhaps in a thousand others. Then we must attend to their most general distinctions; then to distinctions of smaller extent, and so on. It is in this way accordingly that we have advanced in our knowledge of active nature, and are gradually, and by no means slowly, forming assem- blages of events more and more extensive, and distributing these with greater and greater precision into their different classes.

In the zealous and attentive prosecution of this task a very remarkable and interesting observation occurs. In describing those circumstances of similarity amongst events, and particularly in distributing them according to those similarities, it is impossible for us to overlook that constancy which is observed in the changes of nature in the events which are the objects of our contemplation. Events which have once been observed to accompany each other are observed always to do so.

The rising of the sun is always accompanied by the light of day, and his setting by the darkness of night. Sound argument is accompanied by conviction, impulse by motion, kindness by a feeling of gratitude, and the perception of good by desire. The unexpected experience of mankind informs us that the events of nature go on in certain regular trains; and if sometimes exceptions seem to contradict this general affirmation, more attentive observation never fails to remove the exception. Most of the spontaneous events of nature are very complicated; and it frequently requires great attention and penetration to discover the simple event amidst a crowd of unessential circumstances which are at once exhibited to our view. But when we succeed in this discovery, we never fail to acknowledge the perfect uniformity of the event to what has been formerly observed. But this is not all. We firmly believe that this uniformity will still continue; that fire will melt wax, will burn paper, will harden clay, as we have formerly observed it to do; and whenever we have undoubted proofs that the circumstances of situation are precisely the same as in some former case, though but once observed, we expect with irresistible and unshaken confidence that the event will also be the same.

It is not surely necessary to produce many proofs of the universality of this law of human thought. The whole language and actions of men are instances of the fact. In all languages there is a mode of construction which is used to express this relation as distinct from all others, and the conversation of the most illiterate never confounds them, except when the conceptions themselves are confounded. The general employment of the active and passive verb is regulated by it. *Turris eversa est a millibus; turris eversa est terra motu,* express two relations, and no schoolboy will confound them. The distinction therefore is perceived or felt by all who can speak grammatically. Nor is any language without general terms to express this relation. Nay, it is a fact in the mind of brutes, who hourly show that they expect the same uses of every subject which they formerly made of it; and without this animals would be incapable of subsistence, and man incapable of all improvement. From this alone memory derives all its value; and even the constancy of natural operation would be useless if not matched or adapted to our purposes by this expectation of any confidence in that constancy.

After all the labours of ingenious men to discover the foundation of this irresistible expectation, we must be contented with saying that such is the constitution of the human mind. It is an universal fact in human thought; and, for any thing that has yet been discovered, it is an ultimate fact, not included in any other still more general. We shall soon see that this is sufficient for making it the foundation of true human knowledge, all of which must in like manner be reduced to ultimate facts in human thought. We must consider this undoubted feeling, this persuasion of the constancy of nature, as an instinctive anticipation of events similar to those which we have already experienced. The general analogy of nature should have disposed philosophers to acquiesce in this, however unwelcome to their vanity. In no instance of essential consequence to our safety or well-being are we left to the guidance of our boasted reason; God has given us the surer conduct of natural instincts. No case is so important as this. In none do we so much stand in need of a guide which shall be powerful, infallible, and rapid in its decisions. Without it we must remain incapable of all instruction from experience, and therefore of all improvement.

Our sensations are undoubtedly feelings of our mind. But all those feelings are accompanied by an instinctive reference of them to something distinct from the feelings themselves. Hence arises our perception of external objects, and our very notions of this externity. In like manner, this anticipation of events, this irresistible connection of the idea of fire with the idea of burning, is also a feeling of the mind; and this feeling is by a law of human nature referred, without reasoning, to something external as its cause; and, like our sensation, it is considered as a sign of that external something. It is like the conviction of the truth of a mathematical proposition. This is referred by us to something existing in nature, to a necessary and external relation subsisting between the ideas which are the subjects of the proposition. The conviction is the sign or indication of this relation by which it is brought to our view. In precisely the same manner, the irresistible connection of ideas is interpreted as the sensation or sign of a necessary connection of external things or events. These are supposed to include something in their nature which renders them inseparable companions. To this bond of connection between external things we give the name of Cause. All our knowledge of this relation of cause and effect, is the knowledge or consciousness of what passes in our own minds during the contemplation of the phenomena of nature. If we adhere to this view of it, and put this branch of knowledge on the same footing with those called the abstract sciences, considering only the relations of ideas, we shall acquire demonstrative science. If we take any other view of the matter, we shall be led into inextricable mazes of uncertainty and error.

We see, then, that the natural procedure of our faculty of abstraction and arrangement, in order to acquire a more speedy and comprehensive knowledge of natural events, presents them to our view in another form. We not only see them as similar events, but as events naturally and necessarily conjoined. And the expression of resemblance amongst events is also an expression of concomitancy; and this arrangement of events in consequence of their resemblance is in fact the discovery of those accommodations. The trains of natural appearance being considered as the appointments of the Author of Nature, has occasioned them to be considered also as consequences of laws imposed on his works by their great author, and everything is said to be regulated by fixed laws. But this is the language of analogy. When a sovereign determines on certain trains of conduct for his subjects, he issues his orders. These orders are laws. He enforces the observance of them by his authority; and thus a certain regularity and constancy of conduct is produced. But should a stranger, ignorant of the promulgation of these laws, and of the exerted authority of the magistrate, observe this uniformity of conduct, he would ascribe it to the genius and disposition of the people; and his observation would be as useful to him for directing the tenor of his own conduct, as the knowledge of the subject himself of the real source of this constancy is for directing his.

It is just so in nature. Whilst the theologian pretends, from his discoveries concerning the existence and superintendence of God, to know that the constant accompaniment of events is the consequence of laws which the great Author and Governor of the universe has imposed on his works, the ordinary philosopher, a stranger to this scene, and to the unsearchable operations of the Supreme Mind, must as- There is a great resemblance between the expression natural law and grammatical rule. Rule in strict language implies command; but in grammar it expresses merely a generality of fact, whether of flexion or construction. In like manner, a law of nature is to the philosopher nothing but the expression of a generality of fact. A natural or physical law is a generally observed fact; and whenever we treat any subject as a generally observed fact, we treat it physically. It is a physical law of the understanding that argument is accompanied by conviction; it is a physical law of the affection that distress is accompanied by pity; it is a physical law of the material world that impulse is accompanied by motion. And thus we see that the arrangement of events, or the discovery of those general points of resemblance, is in fact the discovery of the laws of nature; and one of the greatest and most important is, that the laws of nature are constant.

There is no question that this view of the universe is incomparably more interesting and more important than that which is taken by the natural historian; contemplating everything that is of value to us, and, in short, the whole life and movement of the universe. This study, therefore, has been dignified with the name of Philosophy and of Science; and natural history has been considered as of importance only in as far as it has proved conducive to the successful prosecution of philosophy. But the philosopher claims a superiority on another account. He considers himself as employed in the discovery of causes, saying that philosophy is the study of the objects of the universe as related by causation, and that it is by the discovery of these relations that he communicates to the world such important knowledge. Philosophy, he says, is the science of causes. The vulgar are contented to consider the prior of two inseparably conjoined events as the cause of the other; the stroke on a bell, for instance, as the cause of sound. But it has been clearly shown by the philosopher, that between the blow struck on the bell and the sensation of sound there are interposed a long train of events. The blow sets the bell a trembling; this agitates the air in contact with the bell; this agitates the air immediately beyond it; and thus between the bell and the ear may be interposed a numberless series of events, and as many more between the first impression on the ear and that last impression on the nerve by which the mind is affected. He can no longer therefore follow the nomenclature of the vulgar. Which of the events of this train, therefore, is the cause of the sensation? None of them. It is that something which inseparably connects any two of them, and constitutes their bond of union. These bonds of union or causes he considers as residing in one or both of the connected objects; diversities in this respect must therefore constitute the most important distinctions between them. They are accordingly with great propriety called the qualities, the properties, of these respective subjects.

As the events from which we infer the existence of these qualities of things resemble in many respects such events as are the consequences of the exertion of our own powers, these qualities are frequently denominated powers, forces, energies. Thus, in the instance which has just now been given of the sound of a bell, we infer the powers of impulse, elasticity, nervous irritability, and animal sensibility. In consequence of this inference of a necessary connection between the objects around us, we not only infer the posterior event from the prior, or, in common language, the effect from the cause, but we also infer the prior from the posterior, the cause from the effect. We not only expect that the presence of a magnet will be followed by certain motions in iron filings, but when we observe such motions, we infer the presence and agency of a magnet. Joy is inferred from merriment, poison from death, fire from smoke, and impulse from motion. And thus the appearances of the universe are the indications of the powers of the objects in it. Appearances are the language of nature, informing us of their causes. And as all our knowledge of the sentiments of others is derived from our confidence in their veracity, so all our knowledge of nature is derived from our confidence in the constancy of natural operations. A veracity and credulity necessarily resulting from that law of our mental constitution by which we are capable of speech, conduct us in the one case; and the constancy of nature, and the principle of induction, by which we infer general laws from particular facts, conduct us in the other. As human sentiment is inferred from language, and the existence of external things from sensation, so are the laws of nature, and the powers of natural objects, inferred from the phenomena. It is by the successful study of this language of nature that we derive useful knowledge. The knowledge of the influence of motives on the mind of man enables the statesman to govern kingdoms, and the knowledge of the powers of magnetism enables the mariner to pilot a ship through the pathless ocean.

Such are the lofty pretensions of philosophy. It is to be wished that they should be well founded; for we may be persuaded that a mistake in this particular will be fatal to the advancement of knowledge. An author of great reputation gives us an opportunity of deciding this question in the way of experiment. He says that the ancients were philosophers, employed in the discovery of causes, and that the moderns are only natural historians, contenting themselves with observing the laws of nature, but paying no attention to the causes of things. If he speak of their professed aim, we apprehend that the assertion is pretty just in general. With very few exceptions indeed it may be affirmed of his favourite Aristotle, the philosopher Ἀριστοτέλης, and of Sir Isaac Newton. We select these two instances, both because they are set in continual opposition by this author, and because it will be allowed that they were the most eminent students of nature (for we must not yet call them philosophers) in ancient and modern times. Aristotle's professed aim, in his most celebrated writings, is the investigation of causes; and, in the opinion of this author, he has been so successful, that he has hardly left any employment for his successors besides that of commenting upon his works. We must, on the other hand, acknowledge that Newton makes no such pretensions, at least in that work which has immortalized his name, and that his professed aim is merely to investigate the general laws of the planetary motions, and to apply these to the explanation of particular phenomena. Nor will we say that he has left no employment for succeeding inquirers; but, on the contrary, confess that he has only begun the study, has discovered but one law, and has enabled us to explain only the phenomena comprehended in it alone. But he has not been unsuccessful; his investigation has been complete; and he has discovered, beyond all possibility of contradiction, a fact which is observed through the whole extent of the solar system, namely, that every body, nay, that every particle in it, is continually deflected toward every other body, and that every deflection is, in every instance, proportional to the quantity of matter in that body toward which the deflection is directed, and to the reciprocal of the square of the distance from it. He has therefore discovered a physical law of immense extent. Nor has he been in any degree less successful in the explanation of particular phenomena. Of this there cannot be given a better instance

1 Ancient Metaphysics. than the explanation of the lunar motions from the theory of gravity begun by Newton, *Mathesi sua faciem preferente*, and now brought to such a degree of perfection, that if the moon's place be computed from it for any moment within the period of two thousand years back, it will not be found to differ from the place on which she was actually observed by one hundredth part of her own breadth.

Much has been written upon this subject. The most acute observation and the soundest judgment have been employed in the study; and we may venture to say that considerable progress has been made in pneumatology. Many laws of human thought have been observed, and very distinctly marked; and philosophers are busily employed, some of them with considerable success, in the distribution of them into subordinate classes, so as to know their comparative extent, and to mark their distinguishing characters, with a precision similar to that which has been attained in botany and other parts of natural history, so that we may hope that this study will advance like others. But in all these researches no phenomena have occurred which look like the perception or contemplation of these separate objects of thought, these philosophical causes, this power in abstracto. No philosopher has ever pretended to state such an object of the mind's observation, or attempted to group them into classes.

We may say at once, without entering into any detail, that those causes, those bonds of necessary union between the naturally conjoined events or objects, are not only perceived by means of the events alone, but are perceived solely in the events, and cannot be distinguished from the conjunctions themselves. They are neither the objects of separate observation, nor the productions of memory, nor inferences drawn from reflection on the laws by which the operation of our own minds are regulated; nor can they be derived from other preceptions in the way of argumentative inference. We cannot infer the paroxysm of terror from the appearance of impending destruction, or the fall of a stone when not supported, as we infer the incommensurability of the diagonal and side of a square. This last is implied in the very conception or notion of a square, not as a consequence of its other properties, but as one of its essential attributes; and the contrary proposition is not only false, but incapable of being distinctly conceived. This is not the case with the other phenomenon, or any matter of fact. The proofs which are brought of a mathematical proposition are not the reason of its being true, but the steps by which this truth is brought into our view; and frequently, as in the instance now given, this truth is perceived, not directly, but consequentially, by the inconceivableness of the contrary proposition.

Mr Hume derives this irresistible expectation of events from the known effect of custom, the association of ideas, theory. The co-related event is brought into the mind by this well-known power of custom, with that vivacity of conception which constitutes belief or expectation. But without insisting on the futility of his theory of belief, it is sufficient to observe, that this explanation begs the very thing to be proved, when it ascribes to custom a power of any kind. It is the origin of this very power which is the subject in dispute. Besides, upon the genuine principles of scepticism, this custom involves an acknowledgment of past events, of something different from present impressions, which, in this doctrine, if doctrine it can be called, are the only certain existences in nature; and, lastly, it is known that one clear experience is a sufficient foundation for this unshaken confidence and anticipation. General custom can never, upon Mr Hume's principles, give superior vivacity to any particular idea.

This certain nonentity of it as a separate object of observation, and this impossibility to derive the notion of necessary and causal connection between the events of the universe from any source, have induced two of the most acute philosophers of Europe, Leibnitz and Malebranche, to deny that there is any such connection, and to assert that the events of the universe go on in corresponding trains, but without any causal connection, just as a well-regulated clock will keep time with the motions of the heavens, without any kind of dependence upon them. This harmony of events was pre-established by the Author of the universe, in subserviency to the purposes he had in view in its formation; and all those purposes which are cognisable by us may certainly be accomplished by this perfect adjustment. But without insisting on the fantastical wildness of this ingenious whim, it is quite enough to observe, that it also is a begging of the question, because it supposes causation when it ascribes all to the agency of the Deity.

Thus have we searched every quarter, without being able to find a source from which to derive this perception of a necessary connection amongst the events of the universe, or of this confident expectation of the continuance of physical laws; and yet we are certain of the feeling, and of the persuasion, be its origin what it may; for we speak intelligibly on this subject. We speak familiarly of cause, effect, power, energy, necessary connection, motives and their influence, argument and conviction, reasons and persuasion, allurements and emotions, of gravity, magnetism, irritability, &c.; and we carry on conversations on these subjects with much entertainment and seeming instruction. Language is the expression of thought, and every word expresses some notion or conception of the mind; therefore it must be allowed that we have such notions as are expressed by cause, power, energy. But it is here, as in many cases, we perceive a distinction without being able to express it by a definition; and that we do perceive the relation of causation as distinct from all others, and in particular as distinct from the relation of contiguity in time and place, or the relation of agent, action, and patient, must be concluded from the uniformity of language, which never confounds them except on purpose, and when it is perceived. But even here we shall find, that none of the terms used for expressing those powers of substance which are conceived as the causes of their characteristic phenomena, really express anything different from the phenomena themselves. Let any person try to define the terms gravity, elasticity, sensibility, and the like, and he will find that the definition is nothing but a description of the phenomena itself. The words are all derivatives, most of them verbal derivatives, implying action, gravitation, and so on. As the general resemblances in shape, colour, or otherwise, are expressed by the natural historian by generic terms, so the general resemblances in event are expressed by the philosopher in generic propositions, which, in the progress of cultivation, are also abbreviated into generic terms.

This abundantly explains the consistency of our language on this subject, both with itself and the operations of nature, without, however, affording any argument for the truth of the assumption, that causes are the objects of philosophical research as separate existences; or that this supposed necessary connection is a necessary truth, whether supreme or subordinate. But since the perception of it has its foundation in the constitution of the human mind, it seems entitled to the name of a first principle. We are hardly allowed to doubt of this, when we consider the importance of it, and the care of nature to secure us, in all things essential to our safety and well-being, from all danger, from inattention, ignorance, or indolence, by an instinct infallible in its information and instantaneous in its decisions. "It would not be like her usual care," says Hume, "if this operation of the mind, by which we infer like effects from like causes, and vice versa, were intrusted to the fallacious deduction of our reason, which is slow in its operations, appears not in any degree during the first years of infancy, and in every age and period of human life is extremely liable to error. It is more conformable to her ordinary caution to secure so necessary an act of the mind by some instinct, or blind tendency, which may be infallible and rapid in all its operations, may discover itself at the first appearance of life, and may be independent of all the laboured deductions of reason. As she has taught us the use of our limbs, without giving us any knowledge of the nerves and muscles by which they are actuated; so she has implanted in us an instinct, which carries forward the thought in a course conformable to that established among external objects, though we be ignorant of the powers and forces on which this regularity depends."

Such a knowledge is quite unnecessary, and therefore causes are no more cognisable by our intellectual powers than colours by a man born blind; nay, whoever will be at the pains to consider this matter agreeably to the received rules and maxims of logic, will find that necessary connection, or the bond of causation, can no more be the subject of philosophical discussion by man than the ultimate nature of truth. It is precisely the same absurdity or incongruity as to propose to examine light with a microscope. Other rational creatures may perceive them as easily as we hear sounds. All that we can say is, that their existence is probable, but by no means certain. Nay, it may be, though we may never know it, that we are not the efficient causes of our own actions, which may be effected by the Deity or by ministering spirits; and this may even be true in the material world. But all this is indifferent to the real occupation of the philosopher, and does not affect either the certainty, the extent, or the utility of the knowledge which he may acquire.

We are now able to appreciate the high pretensions of the philosopher, and his claim to scientific superiority. We now see that this can neither be founded on any scientific superiority of his object, nor of his employment. His object is not causes, and his discoveries are nothing but the discovery of general facts; the discovery of physical laws; and his employment is the same with that of the descriptive historian. He observes and describes with care and accuracy the events of nature; and then he groups them into classes, in consequence of resembling circumstances, detected in the midst of many others which are dissimilar and occasional. By gradually throwing out more circumstances of resemblance, he renders his classes more extensive; and by carefully marking those circumstances in which the resemblance is observed, he characterizes all the different classes; and by a comparison of these with each other, in respect to the number of resembling circumstances, he distributes his classes according to their generality and subdivision; thus exhausting the whole assemblage, and leaving nothing unarranged but accidental varieties. In this procedure it is to be remarked, that every grouping of similar events is, ipso facto, discovering a general fact, a physical law; and the expression of this assemblage is the expression of the physical law. And as every observation of this constancy of fact affords an opportunity for exerting the distinctive inference of natural connection between the related subjects, every such observation is the discovery of a power, property, or quality of natural substance. From what has been said, this observation of event is all we know of the connection, all we know of the natural power. And when the philosopher proceeds farther to the arrangement of events, according to their various degrees of complication, he is, ipso facto, making an arrangement of all natural powers according to their various degrees of subordinate influence. Thus his occupation is perfectly similar to that of the descriptive historian, namely, classification and arrangement; and this constitutes all the science attainable by both.

Philosophy may therefore be defined the study of the phenomena of the universe, with a view to discover the general laws which indicate the powers of natural substances, to explain subordinate phenomena, and to improve art; or, in compliance with that natural instinct so much spoken of, philosophy is the study of the phenomena of the universe, with a view to discover their causes, to explain subordinate phenomena, and to improve art. The task is undoubtedly difficult, and will exercise our noblest powers. The employment is manly in itself; and the result of it important. It therefore justly merits the appellation of Philosophy, although its objects are nowise different from what occupy the attention of other men.

The employment of the philosopher, like that of the natural historian, is threefold, viz. description, arrangement, and reference; whilst the objects are not things, but events. The description, when employed about events, may be more properly termed history. A philosophical history of nature consists in a complete or copious enumeration and narration of facts, properly selected, cleared of all unnecessary or extraneous circumstances, and accurately narrated. This constitutes the materials of philosophy. We cannot give a better example of this branch of philosophical occupation than astronomy. From the beginning of the Alexandrian school to this day, astronomers have been at immense pains in observing the heavenly bodies, in order to detect their true motions. This has been a work of prodigious difficulty; for the appearances are such as might have been exhibited although the real motions had been extremely different. Not that our senses give us false information; but we form hasty, and frequently false judgments, from these informations; and call those things deceptions of sense, which are in fact errors of judgment. But the true motions have at last been discovered, and have been described with such accuracy, that the history may be considered as nearly complete. This is to be found in the usual systems of astronomy, where the tables contain a most accurate and synoptical account of the motion, so that we can tell with precision in what point of the heavens a planet has been seen at any instant that can be named.

Sir Isaac Newton's Optics is such another perfect model of philosophical history, as far as it goes. This part of philosophy may be called Phenomenology. Having in this manner obtained the materials of philosophical description, we must put them into a compendious and perspicuous form, so that a general knowledge of the universe may be easily acquired and firmly retained. This is to be done by classification and arrangement, and this classification must proceed upon resemblances observed in the events; and the subsequent arrangement must be regulated by the distinctions of which those resemblances are still susceptible. This assemblage of events into groups must be expressed. They are facts, therefore the expression must be propositions. These propositions must be what the logicians call general or abstract propositions; for they express, not any individual fact of the assemblage, but that circumstance in which they all resemble. Such propositions are the following: Proof is accompanied by belief; kindness is accompanied by gratitude; impulse is accompanied by motion. These are usually called general facts, but there are none, such: every fact is individual. This language, however inaccurate, is very safe from misconstruction, and we may use it without scruple. These propositions are natural or physical laws, and then the detecting or marking those resemblances in event is the investigation of physical laws; and we may denominate this employment of the philosopher Investigation.

In the prosecution of this task, it will be found that the similarities of fact are of various extent. And thus we shall form physical laws of various extent, and we shall also find that some are subordinate to others; for the resemblance of a number of facts in one circumstance does not hinder a part of them from also resembling in another circumstance; and thus we shall find subordinations of fact in the same way as of quiescent qualities. And it is found here, as in natural history, that our assemblage of resembling events will be the more extensive as the number of resembling circumstances is smaller; and thus we shall have kingdoms, classes, orders, genera, and species of phenomena, which are expressed by physical laws of all those different ranks.

It has already been observed, that this observation of physical laws is always accompanied by a reference of that uniformity of event to a natural bond of union between the concomitant facts which is conceived by us as the cause of this concomitancy; and therefore this procedure of the philosopher is considered as the discovery of those causes, that is, the discovery of those powers of natural substances which constitute their physical relations, and may justly be called their distinguishing qualities or properties. This view of the matter gives rise to a new nomenclature and language. We give to those powers generic names, such as sensibility, intelligence, irritability, gravity, elasticity, fluidity, magnetism, and the like. These terms, without exception, mark resembling circumstances of event; and no other definition can be given of them except a description of these circumstances. In a few cases which have been the subjects of more painful or refined discussion, we have proceeded farther in this abbreviation of language.

We have framed the verb "to gravitate," and also the verbal noun "gravitation," which purely expresses the fact, the phenomenon, but is conceived to express the operation or energy of the cause or natural power. It is of importance to keep in mind this metaphysical remark on these terms; for a want of attention to the pure meaning of the words has frequently occasioned very great mistakes in philosophical science. We may with propriety call this part of the philosopher's employment Attiologia.

We shall give an instance of its most successful application to the class of events already adduced as an example of philosophical history or phenomenology. Kepler, a celebrated Prussian astronomer, having maturely considered the phenomena recorded in the tables and observations of his predecessors, discovered, amidst all the varieties of the planetary motions, three circumstances of resemblance, which are now known by the name of Kepler's Laws. 1. All the planets describe ellipses, having the sun in one focus. 2. The elliptical areas described by a planet in the different parts of its orbit are proportional to the times of description. 3. The squares of the periodic times are proportional to the cubes of the mean distances from the sun. By this observation or discovery, the study of the planetary motions was greatly promoted, and the calculation of their appearances was now made with a facility and an accuracy which surpassed all hopes; for the calculation of the place of a planet at any proposed instant was reduced to the geometrical problem of cutting off an area from an ellipse of known dimensions, which should bear the same proportion to the whole area, as the time for the duration of which the motion is required has to the known time of a complete revolution.

Long after this discovery of Kepler, Sir Isaac Newton found that these laws of Kepler were only particular cases of a fact or law still more general. He found that the deflections of the planets from uniform rectilineal motion were all directed to the sun; and that the simultaneous deflections were inversely proportional to the squares of the distances from that body. Thus was established a physical law of vast extent. But further observation showed him, that the motion of every body of the solar system was compounded of an original motion of projection, combined with a deflection towards every other body; and that the simultaneous deflections were proportional to the quantity of matter in the body towards which they were directed, and to the reciprocal of the square of the distance from it. Thus was the law made still more general. But he did not stop here. He compared the deflection of the moon in her orbit with the simultaneous deflection of a stone thrown from the hand, and describing a parabola; and he found that they followed the same law, that is, that the deflection of the moon in a second, was to that of the stone in the same time, as the square of the stone's distance from the centre of the earth... to the square of the moon's distance from it. Hence he concluded, that the deflection of a stone from a straight line was just a particular instance of the deflections which took place throughout the whole solar system. The deflection of a stone is one of the indications it gives of its being *gravis* or heavy, whence he calls it *gravitation*. He therefore expresses the physical law which obtains throughout the whole solar system by saying that "every body *gravitates* to every other body; and the gravitations are proportional to the quantity of matter in that other body, and inversely proportional to the square of the distance from it."

Thus we see how the arrangement of the celestial phenomena terminated in the discovery of physical laws; and that the expression of this arrangement is the law itself. Since the fall of a heavy body is one instance of the physical law, and since this fall is considered by all as the effect of its weight, and this weight is considered as the cause of the fall, the same cause is assigned for all the deflections observed in the solar system, and all the matter in it is found to be under the influence of this cause, or to be heavy; and thus his doctrine has been denominated the *system of universal gravitation*.

Philosophers have gone farther, and supposed that gravity is a power, property, or quality, residing in all the bodies of the solar system. Sir Isaac Newton does not expressly say so, at least in that work where he gives an account of these discoveries. He contents himself with the immediate consequence of the first axiom in natural philosophy, viz. that every body remains in a state of rest, or of uniform rectilineal motion, unless affected by some moving force. Since the bodies of the solar system are neither in a state of rest, nor of uniform rectilineal motion, they must be considered as so affected; that is, that there operates on every one of them a moving force, directed towards all the others, and having the proportions observed in the deflection.

Other philosophers have endeavoured to show, that this general fact, detected by Sir Isaac Newton, is included in another still more general, viz. that every body moves which is impelled by another body in motion. They assert, that all the bodies of the solar system are continually impelled by means of a fluid which they call *ether*, which is moving in all places, and in all directions, or in circular vortices, and hurries along with it the planets and all heavy bodies. It would seem that the familiarity of motion produced by impulse, at least in those instances in which our own exertions are most employed, has induced philosophers to adopt such notions; perhaps, too, they are influenced by an obscure and indistinct notion affixed to the term action, as applied to changes in the material world, and which has given rise to an axiom, "that a body cannot act at a distance, or where it is not," and thus have thought themselves obliged to look out for an immediate and contiguous agent in all these phenomena.

But the philosophers who profess to be most scrupulous in their adherence to the rules of philosophic discussion deny the legitimacy of this pretended investigation of causes, saying that this doctrine is in direct opposition to the procedure of the mind in acquiring the knowledge of causes. Since the fact of impulse is not really observed in the celestial deflections, nor in the motions of heavy bodies, the law cannot be inferred. They say that it is not even necessary to show that the phenomena of the celestial motions are unlike the phenomena of impulse, although this can be done in the completest manner. It is enough that neither the fluid nor the impulse are observed; and therefore they are in the right when they assert that there is inherent in, or accompanies, all the bodies of the system, a power by which they deflect to one another. The debate is foreign to our present purpose, which is only to show how the observation and arrangement of phenomena terminate in the discovery of their causes, or the discovery of the powers or properties of natural substances. This is a task of great difficulty, as it is of great importance.

There are two chief causes of this difficulty. 1. In most of the spontaneous phenomena of nature there is a complication of many events, and some of them escape our observation. Attending only to the most obvious or remarkable, we conjoin these only in our imagination, and are apt to think these the concomitant events in nature, the proper indication of the cause, and the subjects of this philosophical investigation, and to suppose that they are always conjoined by nature. Thus it was thought that there resided in a vibrating chord a power by which the sensation of sound was excited, or that a chord had a sounding quality. But it appears clearly from observation that there is an inconceivable number of events interposed between the vibration of the chord and the sensitive affection of our ear; and therefore, that sound is not the effect of the vibration of the chord, but of the very last event of this series; and this is completely demonstrated by showing that the vibration and the sound are not necessarily connected, because they are not always connected, but require the interposition of air or of some other elastic body. These observations show the necessity of the most accurate and minute observation of the phenomena, that none of those intermediate events may escape us, and we be thus exposed to the chance of imaginary connections between events which are really far sundered in the procedure of nature. As the study has improved, mistakes of this kind have been corrected; and philosophers have become careful to make their trains of events under one name as short as possible. Thus, in medicine, a drug is no longer considered as a specific remedy for the disease which is sometimes cured when it has been used, but is denominated by its most immediate operation on the animal frame; it is no longer called a febrifuge, but a sudorific.

2. When many natural powers combine their influence in a spontaneous phenomenon of nature, it is frequently very difficult to discover what part of the complicated effect is the effect of each; and to state those circumstances of similarity which are the foundation of a physical law, or entitle us to infer the agency of any natural power. The most likely method for insuring success in such cases is to get rid of this complication of event, by putting the subject into such a situation that the operation of all the known powers of nature shall be suspended, or so modified as that we may perfectly understand their effects. We can thus appreciate the effects of such as we could neither modify nor suspend, or we can discover the existence of a new law, the operation of a new power.

This, which is called making an experiment, is, of all, the most effectual way of advancing in the knowledge of mental philosophy, and it has been called Experimental Philosophy. It seems, however, at first sight, in direct opposition to the procedure of nature in forming general laws. These are formed by induction from multitudes of individual facts, and must be affirmed to no greater extent than the induction on which they are founded. Yet it is a matter of fact, a physical law of human thought, that one simple, clear, and unequivocal experiment gives us the most complete confidence in the truth of a general conclusion from it to every similar case. Whence this anomaly? It is not an anomaly or contradiction of the general maxim of philosophical investigation, but the most refined application of it. There is no law more general than this, that "Nature is constant in all her operations." The judicious and simple form of our experiment insures us in the complete knowledge of all the circumstances of the event. Upon this supposition, and upon this alone, we consider the experiment as the faithful representative of every possible case of the conjunction. This will be more minutely considered afterwards. The last branch of philosophical occupation is the explanation of subordinate phenomena. This is nothing more than the referring any particular phenomenon to that class in which it is included; or, in the language of philosophy, it is the pointing out the general law, or that general fact of which the phenomenon is a particular instance. Thus the feeling of the obligations of virtue is thought to be explained when it is shown to be a particular case of that regard which every person has for his dearest interests. The rise of water in pumps is explained when we show it to be a particular case of the pressure of fluids, or of the air. The general law under which we show it to be properly arranged is called the principle of the explanation, and the explanation itself is called the theory of the phenomenon.

Thus Euler's explanation of the lunar irregularities is called a theory of the lunar motions on the principle of gravitation. This may be done either in order to advance our own knowledge of nature, or to communicate it to others. If done with the first view, we must examine the phenomenon minutely, and endeavour to detect every circumstance in it, and thus discover all the known laws of nature which concur in its production; we then appreciate the operation of each, according to the circumstances of its exertion; we then combine all these, and compare the result with the phenomenon. If they are similar, we have explained the phenomenon. We cannot give a better example than Franklin's explanation of the phenomena of thunder and lightning.

If we explain a phenomenon from known principles, we proceed synthetically from the general law already established and known to exert its influence in the present instance. We state this influence both in kind and degree, according to the circumstances of the case; and having combined them, we compare the result with the phenomenon, and show their agreement, and thus it is explained. Thus, because all the bodies of the solar system mutually gravitate, the moon gravitates to the sun as well as to the earth, and is continually, and in a certain determinate manner, deflected from that part which she would describe did she gravitate only to the earth. Her motion round the earth will be retarded during the first and third quarters of her orbit, and accelerated during the second and fourth. Her orbit and her period will be increased during our winter, and diminished during our summer. Her apogee will advance, and her nodes will recede; the inclination of her orbit will be greatest when the nodes are in syzygie, and least when they are in quadrature; and all these variations will be in certain precise degrees. Then we show that all these things actually obtain the lunar motions, and they are considered as explained.

This summary account of the object and employment in all philosophical discussion is sufficient for pointing out its place in the circle of the sciences, and will serve to direct us to the proper methods of prosecuting it with success. Events are its object; and they are considered as connected with each other by causation, which may therefore be called the philosophical relation of things. The following may be adopted as the fundamental proposition on which all philosophical discussion proceeds, and under which every philosophical discussion or discovery may be arranged:

"Every change that we observe in the state or condition of things is considered by us as an effect, indicating the agency, characterizing the kind, and determining the degree of its inferred cause."

As thus enounced, this proposition is evidently a physical law of human thought. It may be enounced as a necessary and independent truth, by saying that every change in the state and condition of things is an effect, &c. And accordingly it has been so enounced by Dr Reid, and its title to this denomination has been abundantly supported by him. But we have no occasion to consider it as possessing this quality. We are speaking of philosophy, which is something contingent, depending on the existence and constitution of an intellectual being such as man; and, in conformity to the view which we have endeavoured to give of human knowledge in the subjects of philosophical relations, it is quite sufficient for our purpose that we maintain its title to the rank of an universal law of human thought. This will make it a first principle, even although it may not be a necessary truth.

All the proof necessary for this purpose is universality of fact; and we believe this to be without exception. We are not to expect that all mankind have made, or will ever make, a formal declaration of their opinion; but we may venture to say that all have made it, and continually do make it, virtually. What have the philosophers of all ages been employed about except the discovery of the causes of those changes that are incessantly going on? "Nil turpis physicum," says Cicero, "quam fieri sine causa quidquid dicere." Human curiosity has been directed to nothing so powerfully and so constantly as to this. Many absurd causes have been assigned for the phenomena of the universe; but no set of men have ever said that they happened without a cause. This is so repugnant to all our propensities and instincts, that even the atheistical philosophers, who, of all others, would have profited most by the doctrine, have never thought of advancing it. To avoid so shocking an absurdity, they have rather allowed that chance, and the confluence of atoms, are the causes of the beautiful arrangements of nature. The thoughtless vulgar are no less solicitous than the philosophers to discover the cause of things; and the poet expresses the natural and instinctive passion of all men when he says,

Felix qui potuit rerum cognoscere causas.

And this anxiety is not to nourish, but to get rid of superstitious fears; for thus

metus omnes, et inexorabile fatum Subjecit pedibus, strepitumque Acherontis avai.

Had men never speculated, their conduct alone gives sufficient evidence of the universality of the opinion. The whole conduct of man is regulated by it; nay, almost wholly proceeds upon it, in the most important matters, and where experience seems to leave us in doubt; and to act otherwise, as if any thing whatever happened without a cause, would be a declaration of insanity. Dr Reid has beautifully illustrated this truth, by observing, that even a child will laugh at you if you try to persuade him that the top, which he misses from the place where he left it, was taken away by nobody. You may persuade him that it was taken away by a fairy or a spirit; but he believes no more about this nobody than the master of the house, when he is told that nobody was the author of any piece of theft or mischief.

What opinion would be formed, says Dr Reid, of the intellects of the jurymen, on a trial for murder by persons unknown, who should say that the fractured skull, the watch and money gone, and other like circumstances, might possibly have no cause? He would be pronounced insane or corrupted.

We believe that Mr Hume is the first author who has ventured to call the truth of this opinion in question; and even he does it only in the way of mere possibility. He acknowledges the generality of the opinion, and he only objects to it merely because it does not quadrate with his theory of belief, and therefore it may happen that some men may have no such opinion. But it must be observed on this oc... of occasion, that the opinion of a philosopher is of no greater weight in a case like this than that of a ploughboy. If it be a first principle, directing the opinions and actions of all, it must operate on the minds of all. The philosopher is the only person who may chance to be without it; for it requires much labour, and long habits resolutely maintained, to warp our natural sentiments; and experience shows us that they may be warped if we are at sufficient pains. It is also worthy of remark, that this philosopher seems as much under the influence of this law as ordinary mortals. It is only when he is aware of its not tallying with his other doctrines that his scruples appear. Observe how he speaks when off his guard: "As to those impressions which arise from the senses, their ultimate cause is, in my opinion, perfectly inexplicable by human reason; and it will always be impossible to decide with certainty whether they arise immediately from the object, are produced by the creative power of the mind, or are derived from the Author of our being."

Amongst these alternatives he never thought of their not being derived from any cause. But it is not enough to show that this is a physical law of the human mind. We have assumed it as a first principle, the foundation of a whole science, and therefore not included in or derived from anything more general. Mr Hume's endeavours to prove that it is not a necessary truth, show with sufficient evidence that most attempts to derive it in the way of argument are petitio principii; a thing very commonly met with in all attempts to prove first principles. It cannot be proved by induction that every event has a cause, because induction always supposes an observed fact or event. Now in by far the greater number of events the causes are unknown. Perhaps in no event whatever do we know the real cause, or that power or energy which, without any intervention, produces the effect. No man can say that, in the simplest event which he ever observed, he was fully apprised of every circumstance which concurred to its production. We suppose that no event in nature can be adduced more simple than the motion of a suspended glass ball when gently struck by another glass ball; and we imagine that most of our readers will say that they perfectly see every thing which happens in this phenomenon. We believe, too, that most of our readers are of opinion that a body is never put in motion but by the impulse of another, except in the cases of animal motion; and that they are disposed to imagine that magnets put iron in motion, and that an electrified body moves another, by means of an interposed though invisible fluid somehow circulating round them. Now we must inform such readers, that unless the stroke has been very smart, so smart indeed as to shatter the glass balls, the motion of the suspended ball was produced without impulse; that is, the two balls were not in contact during the stroke, and the distance between them was not less than the nine thousandth part of an inch, and probably much greater. We must say farther, that it is not certain that even the violent stroke, such as would shatter them to pieces, is enough to bring them into real contact.

Unless, therefore, our readers are willing to allow that the suspended ball was put in motion by a repulsive force inherent in one or both balls, they must acknowledge that they do not fully know all the circumstances of this so simple phenomenon, or all the train of events which happen in it; and therefore they are reduced to the necessity of supposing, although they do not see it, an intervening fluid or matter, by the immediate action of the adjoining particles of which the motion is produced.

This being the case in the simplest phenomenon that we can pitch upon, what shall we say of the numberless multitudes which are incomparably more complex. Must we not acknowledge that the efficient causes, even in the vulgar sense of the word, the immediately preceding events, are unknown, because the conjunctions are not observed; and therefore it cannot be said that it is from experimental induction that this truth gains universal belief. Experience, so far from supporting it as a direct proof, seems rather the strongest argument against it; for we have no experiment of unquestionable authority but the narrow circle of our own power exerted upon our thoughts and actions. And even here there are perhaps cases of change where we cannot say with certainty that we perceive the efficient cause. Nothing seems to remain, therefore, but to allow that this physical law of human judgment is instinctive, a constituent of the human soul, a first principle, and incapable of any other proof than the appeal to the feelings of every man.

Simply to state, that every change is considered as an effect, is not giving the whole characters of this physical law. The cause is not always, perhaps never, observed, but inferred from the phenomena. The inference is therefore in every instance dependent on the phenomenon. The phenomenon is to us the language of nature. It is therefore the sole indication of the cause and of its agency; it is the indication of the very cause, and of no other. The observed change therefore characterizes the cause, and marks its kind. This is confirmed by every word of philosophical language, where, as has already been observed, the names of the inferred powers of nature are nothing but either abbreviated descriptions of the phenomena, or terms which are defined solely by such descriptions. In like manner, the phenomenon determines the cause in a particular degree, and in no other; and we have no immediate measure of the degree of the cause but the phenomenon itself. We take many measures of the cause, it is true; but on examination they will be found not to be immediate measures of the cause, but of the effect. Assuming gravitation as the cause of the planetary deviations from uniform rectilineal motion, we say that the gravitation of the moon is but thirty-seventh part of the gravitation of a stone thrown from the hand; but we say this only from observing that the deflection of the stone is three thousand six hundred times greater than the simultaneous deflection of the moon. In short, our whole knowledge of the cause is not only founded on our knowledge of the phenomenon, but it is the same. This will be found a remark of immense consequence in the prosecution of philosophical researches; and a strict attention to it will not only guard us against a thousand mistakes into which the reasoning pride of man would continually lead us, but will also enable us fully to detect any egregious and fatal blunders made in consequence of this philosophical vanity. Nothing can be more evident than that, whenever we are puzzled, it would be folly to continue groping amongst those obscure beings called causes, when we have their prototypes, the phenomena themselves, in our hands.

Such is the account which may be given of philosophy, the study of the works of God, as related by causation. It is of vast extent, reaching from an atom to the glorious Author of the universe, and contemplating the whole connected chain of intelligent, sensitive, and inanimate beings. The philosopher makes use of the descriptions and arrangements of the natural historian as of mighty use to himself in the beginning of his career, confiding in the uniformity of nature, and expecting that similarity in the quiescent properties of things will be accompanied by some resemblances in those more important properties which constitute their mutual dependencies, linking them together in a great and endlessly-ramified chain of events.

We have endeavoured to ascertain with precision the peculiar province of philosophy, both by means of its object and its mode of procedure. After this it will not require many words to point out the methods for prosecuting the study with expedition and with success. The rules of philosophizing, which Newton premises in his account of the planetary motions, which he so scrupulously followed, and with a success which gives them great authority, are all in strict conformity to the view we have now given of the subject.

The chief rule is, that similar causes are to be assigned to similar phenomena. This is indeed the source of all our knowledge of connected nature; and, without it, the universe would only present to us an incomprehensible chaos. It is by no means, however, necessary to join this as a maxim for our procedure; it is an instinctive propensity of the human mind. It is absolutely necessary, on the contrary, to caution us in the application of this propensity. We must be extremely confident in the certainty of the resemblance before we venture to make any inference. We are prone to reason from analogy; the very employment is agreeable, and we are ever disposed to embrace opportunities of engaging in it. For this reason we are satisfied with very slight resemblances, and eagerly run over the consequences, as if the resemblance were complete; and our researches frequently terminate in falsehood.

This propensity to analogical reasoning is aided by another equally strong, and equally useful when properly directed; we mean the propensity to form general laws. This is in fact a propensity to discover causes, which is equivalent to the establishing of general laws. It appears in another form, and is called a love of or taste for simplicity; and this is encouraged or justified, as agreeable to the uniformity and simplicity of nature. "Natura semper sibi similis et consona," says Newton. "Fustra fit per plura, quod fieri potest per pauciora," says another. The beautiful, the wise economy of nature, are phrases in every body's mouth; and Newton enjoins us to adopt no more causes than are sufficient to explain the phenomena. All this is very well, and is true in its own degree; but it is too frequently the subterfuge of human vanity and self-love. This inordinate admiration of the economy and simplicity of nature is generally conjoined with a manifest love of system, and with the actual production of some new system, where from one general principle some extensive theory or explanation is deduced and offered to the world. The author sees a sort of resemblance between a certain series of phenomena and the consequences of some principle, and thinks the principle adequate to their explanation. Then, on the authority of the acknowledged simplicity of nature, he roundly excludes all other principles of explanation; because, says he, this principle is sufficient, "et frustra fit per plura," &c. We could point out many instances of this kind in the writings of perhaps the first mathematician and the poorest philosopher of this century; where extensive theories are thus cavalierly exhibited, which a few years' examination have shown to be nothing but analogies, indistinctly observed, and, what is worse, inaccurately applied.

To regulate these hazardous propensities, and thus to keep philosophers in the right path, Newton inculcates another rule, or rather gives a modification of this injunction of simplicity. He enjoins that no cause shall be admitted but what is real. His words are, that "no causes shall be admitted but such as are true, and sufficient to account for the phenomena." We apprehend that the meaning of this rule has been mistaken by many philosophers, who imagine that by true he means causes which really exist in nature, and are not mere creatures of the imagination. We have met with some who would boggle at the doctrines of Aristotle respecting the planetary motions, viz. that they are carried along by conducting intelligent minds, because we know of none such in the universe; and who would nevertheless think the doctrine of the Cartesian vortices deserving of at least an examination, because we see such vortices exist, and produce effects which have some resemblance to the planetary motions, and have justly rejected them, solely because this resemblance has been very imperfect. We apprehend Newton's meaning by these words is, that no cause of any event shall be admitted, or even considered, which we do not know to be actually concurring or exerting some influence in that very event. If this be his meaning, he would reject the Cartesian vortices, and the conducting spirits of Aristotle, for one and the same reason; not because they were not adequate to the explanation, nor because such causes do not exist in nature, but because we did not see them anyhow concerned in the phenomenon under consideration. We neither see a spirit nor a vortex, and therefore need not trouble ourselves with inquiring what effects they would produce. Now we know that this was his very conduct, and what has distinguished him from all philosophers who preceded him, though many, by following his example, have also been rewarded by similar success. This has procured to Newton the character of the modest philosopher; and modest his procedure may, for distinction's sake, be called, because the contrary procedure of others did not originate so much from ignorance as from vanity. Newton's conductor in this was not modesty, but sagacity, prudence, caution, and, to say it purely, it was sound judgment.

For the bonds of nature, the supposed philosophical causes are not observed; they are only inferred from the phenomena. When two substances are observed, and only when they are observed to be connected in any series of events, we infer that they are connected by a natural power; but when one of the substances is not seen, but fancied, no law of human thought produces any inference whatever. For this reason alone Newton stopped short at the last fact which he could discover in the solar system, that all bodies were deflected to all other bodies, according to certain regulations of distance and quantity of matter. When told that he had done nothing in philosophy, that he had discovered no cause, and that to merit any praise he must show how this deflection was produced, he said that he knew no more than he had told them; that he saw nothing causing this deflection, and was contented with having discovered it so exactly, that a good mathematician could now make tables of the planetary motions as accurate as he pleased, and with hoping in a few years to have every purpose of navigation and of philosophical curiosity completely answered; and he was not disappointed. And when philosophers on all sides were contriving hypothetical fluids and vortices which would produce these deflections, he contented himself with proving the total inconsistency of these explanations with the mechanical principles acknowledged by their authors; showing that they had transgressed both parts of his rule, their causes neither being real, nor sufficient for explaining the phenomena. A cause is sufficient for explaining a phenomenon only when its legitimate consequences are perfectly agreeable to these phenomena.

Newton's discoveries remain without any diminution or change; no philosopher has yet advanced a step farther, but let not the authority, nor even the success, of Newton be our guide. Is his rule founded in reason? It surely is. For if philosophy be the only interpretation of nature's language, the inference of causes from the phenomena, a fancied or hypothetical phenomenon can produce nothing but a fanciful cause, and can make no addition to our knowledge of real nature.

All hypotheses therefore must be banished from philosophical discussion as frivolous and useless, administering to vanity alone. As the explanation of any appearance is nothing but the pointing out the general fact, of which this is a particular instance, a hypothesis can give no explanation; knowing nothing of cause and effect but the conjunction of two events, we see nothing of causation where one of the events is hypothetical. Although all the legitimate consequences of a hypothetical principle should be perfectly similar to the phenomenon, it is extremely dangerous to assume this principle as the real cause. It is illogical to make use of the economy of nature as an argument for the truth of any hypothesis; for, if true, it is a physical truth, a matter of fact, and true only to the extent in which it is observed; and we are not entitled to say that it is so one step farther, therefore not in this case till it be observed. But the proposition that nature is so economical, is false; and it is astonishing that it has been so lazily acquiesced in by the readers of hypotheses; for it is not the authors who are deceived by it; they are generally led by their own vanity. Nothing is more observable than the prodigious variety of nature. That the same phenomena may be produced by different means, is well known to the astronomers, who must all grant that the appearances of motion will be precisely the same whether the earth moves round the sun like the other planets, or whether the sun with his attendant planets moves round the earth; and that the demonstration of the first opinion is had from a fact totally unconnected with all the deflections, or even with their causes; for it may be asserted, that Dr Bradley's discovery of the aberration of the fixed stars, in consequence of the progressive motion of light, was the first thing which put the Copernican system beyond question; and even this is still capable of being explained in another way. The Author of nature seems to delight in variety; and there cannot be named a single purpose on which the most inconceivable fertility in resource is not observed. It is the most delightful occupation of the curious mind and the sensible heart to contemplate the various contrivances of nature in accomplishing similar ends.

As a principle, therefore, on which to found any maxim of philosophical procedure, this is not only injudicious, because imprudent and apt to mislead, but as false, and almost sure to mislead. In conformity to this observation, it must be added, that nothing has done so much harm in philosophy as the introduction of hypotheses.

Authors have commonly been satisfied with very slight resemblances, and readers are easily misled by the appearances of reasoning which these resemblances have countenanced. The ancients, and above all Aristotle, were much given to this mode of explanation, and have filled philosophy with absurdities. The slightest resemblances were with them sufficient foundations of theories. It has been by very slow degrees that men have learned caution in this respect; and we are sorry to say that we are not yet cured of the disease of hypothetical systematizing, and to see attempts made by ingenious men to bring the frivolous theories of antiquity again into credit. Nay, modern philosophers, even of the greatest name, are by no means exempted from the reproach of hypothetical theories. Their writings abound in ethers, nervous fluids, animal spirits, vortices, vibrations, and other invisible agents. We may affirm that all these attempts may be shown to be either unintelligible, fruitless, or false. Either the hypothesis has been such that no consequence can be distinctly drawn from it, on account of its obscurity and total want of resemblance to anything we know; or the just and legitimate consequences of the hypothesis are inconsistent with the phenomena. This is remarkably the case in the hypotheses which have been introduced for the explanation of the mechanical phenomena of the universe. These can be examined by accurate science, and the consequences compared without any mistake; and nothing else but a perfect agreement should induce us even to listen to any hypotheses whatever.

It may be here asked, Whether, in the case of the most perfect agreement, after the most extensive comparison, the hypothesis should be admitted? We believe that this must be left to the feelings of the mind. When the belief is irresistible, we can reason no more. But as there is no impossibility of as perfect an agreement with some other hypothesis, it is evident that it does not convey an irrefragable title to our hypothesis. It is said, that such an agreement authorizes the reception of the hypothetical theory, in the same manner as we must admit that to be the true cipher of a letter which will make perfect sense of it. But this is not true. In deciphering a letter we know the sounds which must be represented by the characters, and that they are really the constituents of speech; but in hypothetical explanations the first principle is not known to exist; nay, it is possible to make two ciphers, each of which shall give a meaning to the letter. Instances of this are to be seen in treatises on the art of deciphering.

We conclude our criticism on hypothetical explanations with this observation, that it is impossible that they can make any addition to our knowledge. In every hypothesis we thrust in an intermediate event between the phenomenon and some general law; and this event is not seen, but supposed. Therefore, according to the true maxims of philosophical investigation, we give no explanation; for we are not by this means enabled to assign the general law in which this particular phenomenon is included. Nay, the hypothesis makes no addition whatever to our list of general laws; for our hypotheses must be selected, in order to tally with all the phenomena. The hypothesis therefore is understood only by and in the phenomena, and it must not be made more general than the phenomena themselves. The hypothesis gives no generalization of facts. Its very application is founded on a great coincidence of facts; and the hypothetical fact is thrust in between two which we really observe to be united by nature. The applicability, therefore, of the hypothesis is not more extensive than the similarity of facts which we observe, and the hypothetical law is not more general than the observed law. Let us then throw away entirely the hypothetical law, and insert the observed one in our list of general laws; it will be in different language from the hypothetical law, but it will express the same facts in nature.

It is in experimental philosophy alone that hypotheses on what can have any just claim to admission; and here they are occasions not admitted as explanations, but as conjectures serving to direct our line of experiments. Effects only appear; and may be used by their appearance, and the previous information of experience, causes are immediately ascertained by the perfect similarity of the whole train of events to other trains formerly observed. Or they are suggested by more imperfect resemblances of the phenomena; and these suggestions are made with stronger or fainter evidence, according as the resemblance is more or less perfect. These suggestions do not amount to a confidential inference, and only raise a conjecture. Wishing to verify or overturn this conjecture, we have recourse to experiment; and we put the subject under consideration in such a situation that we can say what will be the effect of the conjectural cause if real. If this tallies with the appearance, our conjecture has more probability of truth, and we vary the situation, which will produce a new set of effects of the conjectured cause, and so on. It is evident that the probability of our conjecture will increase with the increase of the conformity of the legitimate effects of the supposed cause with the phenomena, and that it will be entirely destroyed by one disagreement. In this way conjectures have their great use, and are the ordinary means by which experimental philosophy is improved. But conjectural systems are worse than nonsense, filling the mind with false notions of nature, and generally leading us into a course of improper conduct when they become principles of action. This is acknowledged even by the abettors of hypothetical systems themselves when employed in overturning those of their predecessors, and establishing their own; witness the successive maintainers of the many hypothetical systems in medicine, which have had their short-lived course within these two last centuries. Let every person, therefore, who calls himself a philosopher, resolutely determine to reject all temptations to this kind of system-making, and let him never consider a composition of this kind as any thing better than the amusement of an idle hour.

After these observations, it cannot require much discussion to mark the mode of procedure which will insure progress in all philosophical investigations. The sphere of our intuitive knowledge being very limited, we must be indebted for the greatest part of our intellectual attainments to our rational powers, and it must be deductive. In the spontaneous phenomena of nature, whether of mind or body, it seldom happens that the energy of that natural power, which is the principle of explanation, is so immediately connected with the phenomenon that we can see the connection at once. Its exertions are frequently concealed, and in all cases modified, by the joint exertions of other natural powers; hence the particular exertion of each must be considered apart, and their mutual connection traced out. It is only in this way that we can discover the perhaps long train of intermediate operations, and also see in what manner and degree the real principle of explanation concurs in the ostensible process of nature.

In all such cases it is evident that our investigation (and investigation it most strictly is) must proceed by successive steps, conducted by the sure hand of logical method. To take an instance from the material world, let us listen to Galileo whilst he is teaching his friends the cause of the rise of water in a pump. He says that it is owing to the pressure of the air. This is his principle; and he announces it in all its extent. All matter, says he, is heavy, and in particular air is heavy. He then points out the connection of this general principle with the phenomenon. Air being heavy, it must be supported; it must lie and press on what supports it; it must press on the surface AB of the water in the cistern surrounding the pipe CD of the pump; and also on the water C within this pipe. He then takes notice of another general principle which exerts its subordinate influence in this process. Water is a fluid; a fluid is a body the parts of which yield to the smallest impression, and, by yielding, are easily moved amongst themselves; and no little parcel of the fluid can remain at rest unless it be equally pressed in every direction, but will recede from that side where it sustains the greatest pressure. In consequence of this fluidity, known to be a property of water, if any part of it is pressed, the pressure is propagated through the whole; and if not resisted upon every side, the water will move to that side where the propagated pressure is not resisted. All these subordinate or collateral propositions are supposed to be previously demonstrated or allowed. Water, therefore, must yield to the pressure of the air, unless pressed by it upon every side, and must move to that side where it is not withheld by some opposite pressure. He then proceeds to show, from the structure of the pump, that there is no opposing pressure on the water in the inside of the pump. "For," says he, "suppose the piston thrust down till it touches the surface of the water in the pipe; suppose the piston now drawn up by a power sufficient to lift it, and all the air incumbent on it; and suppose it drawn up a foot or fathom, there remains now nothing that I know of to press on the surface of the water. In short," says he, "gentlemen, it appears to me that the water in the pump is in the same situation that it would be in were there no air at all, but water poured into the cistern to a height AF; such that the column of water FABG presses on the surface AB as much as the air does. Now, in this case, we know that the water at C is pressed upwards with a force equal to the weight of a column of water having the section of the pipe for its base and CH for its height. The water below C, therefore, will be pressed up into the pipe CD, and will rise to G, so that it is on a level with the external water FG; that is, it will rise to H. This is a necessary consequence of the weight and pressure of the incumbent column FABG, and the fluidity of the water in the cistern. Consequences perfectly similar must necessarily follow from the weight and pressure of the air; and therefore, upon drawing up the piston from the surface C of the water with which it was in contact, the water must follow it till it attain that height which will make its own weight a balance for the pressure of the circumambient air. Accordingly, gentlemen, the Italian plumbers inform me that a pump will not raise water quite fifty palms; and from their information I conclude, that a pillar of water fifty palms high is somewhat heavier than a pillar of air of the same base, and reaching to the top of the atmosphere."

Thus is the phenomenon explained. The rise of the water in the pump is shown to be a particular case of the general fact in hydrostatics, that fluids in communicating vessels will stand at heights which are inversely as their densities, or that columns of equal weights are in equilibrio. This way of proceeding is called arguing a priori, or the synthetic method. It is founded on just principles; and the great progress which we have made in the mathematical sciences by this mode of reasoning shows to what length it may be carried with irresistible evidence. It has long been considered as the only inlet to true knowledge; and nothing was allowed to be known with certainty which could not be demonstrated in this way to be true. Accordingly logic, or the art of reasoning, which was also called the art of discovering truth, was nothing but a set of rules for successfully conducting this mode of argument.

Under the direction of this infallible guide, it is not surely unreasonable to expect that philosophy should make sure progress towards perfection; and as we know that the brightest geniuses of Athens and of Rome were for ages solely occupied in philosophical researches in every path of human knowledge, it is equally reasonable to suppose that the progress has not only been sure, but great. We have seen that the explanation of an appearance in nature is nothing but the arrangement of it into that general class in which it is comprehended. The class has its distinguishing mark, which, when it is found in the phenomenon under consideration, fixes it in its class, there to remain for ever an addition to our stock of knowledge. Nothing can be lost any other way but by forgetting it; and the doctrines of philosophers must be stable, like the laws of nature.

We have seen, however, that the very reverse of all this is the case; that philosophy has but very lately emerged from worse than total darkness and ignorance; that what passed under the name of philosophy was nothing but systems of errors, if systems they could be called, which were termed doctrines, delivered with the most imposing apparatus of logical demonstration, but belied in almost every instance by experience, and affording us no assistance in the application of the powers of nature to the purposes of life. Nor will this excite much wonder in the mind of the enlightened reader of the present day, who reflects on the use that in this dialectic process was made of the categories, and the method in which those categories were formed. From first principles so vague in themselves, and so gratuitously assumed, ingenious men might deduce many different conclusions, all equally erroneous; and that this was actually done, no surer evidence can be given, than that hardly a lifetime elapsed when the whole system of doctrines which had captivated the minds of the most penetrating was oftener than once exploded and overturned by It is allowed by all that this has been the case in those branches of study at least which contemplate the philosophical relations of the material world; in astronomy, in mechanical philosophy, in chemistry, in physiology, in medicine, in agriculture. It is also acknowledged, that in the course of less than two centuries we have acquired much knowledge respecting these very subjects, call it philosophy, or by what name you will; so much more conformable to the natural course of things, that the deductions made from it by the same rules of the synthetic method are more conformable to fact, and therefore better fitted to direct our conduct and improve our powers. It is also certain that these bodies of doctrine which go by the name of philosophical systems have much more stability than in ancient times; and though sometimes in part superseded, they are seldom or never wholly exploded.

This cannot perhaps be affirmed with equal confidence respecting those speculations which have our intellect or propensities for their object: And we have not perhaps attained such a representation of human nature as will bear comparison with the original, nor will the legitimate deductions from such doctrines be of much more service to us for directing our conduct than those of ancient times; for whilst we observe this difference between these two general classes of speculations, we may remark, that it is conjoined with a difference in the manner of conducting the study. We have proceeded according to the old Aristotelian method when investigating the nature of mind; yet we see the material philosophers running about, passing much of their time away from books in the shop of the artisan, or in the open fields engaged in observation, labouring with their hands, and busy with experiments. But the speculative on the intellect and the active powers of the human soul seems unwilling to be indebted to any thing but his own ingenuity, and his labours are confined to the closet. In the first class, we have met with something like success, and we have improved many arts; in the other, it is to be feared that we are not much wiser, or better, or happier, for all our philosophical attainments.

Here, therefore, must surely have been some great and fatal mistake. There has indeed been a material defect in our mode of procedure, in the employment of this method of reasoning as an inlet to truth. The fact is, that philosophers have totally mistaken the road of discovery, and have pretended to set out in their investigation from the very point where this journey should have terminated.

The Aristotelian logic, the syllogistic art, that art so much boasted of as the only inlet to true knowledge, and the only means of discovery, is in direct opposition to the ordinary procedure of nature, by which we every day, and in every action of our lives, acquire knowledge and discover truth. It is not the art of discovering truth; it is the art of communicating knowledge, and of detecting error: it is nothing more than the application of this maxim; "Whatever is true of a whole class of objects, is true of each individual of that class." This is not a just account of the art of discovering truth, nor is it a complete account of the art of reasoning. Reasoning is the producing of belief; and whatever mode of argumentation invariably and irresistibly produces belief, is reasoning. The ancient logic supposes that all the first principles are already known, and that nothing is wanted but the application of them to particular facts. But were this true, the application of them, as we have already observed, can hardly be called a discovery. But it is not true; and the fact is, that the first principles are generally the chief objects of our research, and that they have come into view only now and then, as it were by accident, and never by the labour of the logician. He indeed can tell us whether we have been mistaken; for if our general principle be true, it must influence every particular case. If, therefore, it be false in any one of these, it is not a true principle. And it is here that we discover the source of that fluctuation which is so much complained of in philosophy. The authors of systems give a set of consecutive propositions logically deduced from a first principle, which has been hastily adopted, and has no foundation in nature. This does not hinder the amusement of framing a system from it, nor this system from pleasing by its symmetry; and it takes a run: but when an officious follower thinks of making some use of it, which requires the comparison with experience and observation, they are found totally unlike, and the whole fabric must be abandoned as unsound; and thus the successive systems were continually pushing out their predecessors, and presently met with the same treatment.

How was this to be remedied? The ratiocination was seldom egregiously wrong; the syllogistic art had ere now attained a degree of perfection which left little room for improvement, and was so familiarly understood by the philosophical practitioners, that they seldom committed any great blunders. Must we examine the first principles? This was a task quite new in science; and there were hardly any rules in the received systems of logic to direct us to the successful performance of it. Aristotle, the sagacious inventor of those rules, had not totally omitted it; but, in the fervour of philosophical speculation, he had made little use of them. His fertile genius never was at a loss for first principles, which answered the purpose of verbal disquisition, without much risk of being belied on account of its dissimilitude to nature; for there was frequently no prototype with which his systematic doctrine could be compared. His enthusiastic followers found abundant amusement in following his example; and philosophy, being no longer in the hands of men acquainted with the world, conversant in the great book of nature, was now confined almost entirely to recluse monks, equally ignorant of men and of things. But curiosity was awakened, and the men of genius were fretted as well as disgusted with the disquisitions of the schools, which one moment raised expectations by the symmetry of composition, and the next moment blasted them by their inconsistency with experience. They saw that the best way was to begin de novo; to throw away the first principles altogether, without exception or examination, and endeavour to find out new ones which should stand the test of logic; or, in other words, should in every case be agreeable to fact.

Philosophers began to reflect, that under the unnoticed intuition of kind nature we have acquired much useful knowledge. It is therefore highly probable that her method is the most proper for acquiring knowledge, and that by imitating her manner we shall have the like success. We are too apt to slight the occupations of children, whom we may observe continually busy turning every thing over and over, putting them into every situation, and at every distance. We excuse it, saying that it is an innocent amusement; but we should rather say with an ingenious philosopher (Dr Reid), that they are most seriously and rationally employed; they are acquiring the habits of observation, and, by merely indulging an undetermined curiosity, they are making themselves acquainted with surrounding objects; they are struck by similitudes, and amused with mere classification. If some new effect occurs from any of their little plays, they are eager to repeat it. When a child has for the first time tumbled a spoon from the table, and is pleased with its jingling noise upon the floor, if another lie within its reach, it is sure to share the same fate. If the child be indulged in this diversion, it will repeat it with a greediness that deserves our attention. The very first eager repetition shows a confidence in the constancy of natural operations, which we can hardly ascribe wholly to experience; and its keenness to repeat the experiment shows the interest which it takes in the exercise of this most useful propensity. It is beginning the study of nature; and its occupation is the same with that of a Newton computing the motions of the moon by his sublime theory, and comparing his calculus with observation. The child and the philosopher are equally employed in the contemplation of a similarity of event, and are anxious that this similarity shall return. The child, it is true, thinks not of this abstract object of contemplation, but throws down the spoon again to have the pleasure of hearing it jingle. The philosopher suspects that the conjunction of events is the consequence of a general law of nature, and tries an experiment where this conjunction recurs. The child is happy, and eager to enjoy a pleasure which to us appears highly frivolous; but it has the same foundation with the pleasure of the philosopher, who rejoices in the success of his experiment; and the fact, formerly a trifle to both, now acquires importance. Both go on repeating the experiment, till the fact ceases to be a novelty to either; the child is satisfied, and the philosopher has now established a new law of nature.

Such, says this amiable philosopher, is the education of kind nature, who from the beginning to the end of our lives makes the play of her scholars their most instructive lessons, and has implanted in our mind the curiosity and the inductive propensity by which we are enabled and disposed to learn them. The exercise of this inductive principle, by which nature prompts us to infer general laws from the observation of particular facts, gives us a species of logic new in the schools, but as old as human nature. It is certainly a method of discovery; for by these means general principles, formerly unknown, have come into view.

Induction is a just and rational logic; for it is founded on, and indeed is only the habitual application of, this maxim, that "Whatever is true with respect to every individual of a class of events, is true of the whole class." This is just the inverse of the maxim upon which the Aristotelian logic wholly proceeds, and is of equal authority in the court of reason. Indeed, the expression of the general law is only the abbreviated expression of every particular instance. This new logic, therefore, or the logic of induction, must not be considered as subordinate to the old system, or founded upon it. In fact, the use and legitimacy of the Aristotelian logic is founded on the inductive: All animals are mortal; all men are animals; therefore all men are mortal. This is no argument to any person who chooses to deny the mortality of man; for even although he acknowledges his animal nature, he will deny the major proposition.

It is beside our purpose to show how a point so general, so congenial to man, and so familiar, remained so long unnoticed, although the disquisition is curious and satisfactory. It was not till within these two centuries that the increasing demand for practical knowledge, particularly in the arts, made inquisitive men see how useless and insufficient was the learning of the schools in any road of investigation which was connected with life and business; and observe that society had received useful information chiefly from persons actually engaged in the arts which the speculators were endeavouring to illustrate; and that this knowledge consisted chiefly of experiments and observations, the only contributions which their authors could make to science.

The Novum Organum of Bacon, which points out the true method of forming a body of real and useful knowledge, namely, the study of nature in the way of description, observation, and experiment, is undoubtedly the noblest present that science ever received. It may be considered as the grammar of nature's language, and is a counterpart to the logic of Aristotle; not exploding it, but making it effectual.