the founder of experimental science, was born at Pisa on the 15th of February 1564, being descended of a noble and ancient Florentine family, which, under the surname of Bonajuti, afterwards changed to that of Galilei, had filled distinguished offices in the state. His father, Vincenzo Galilei, was a man of considerable talent and learning, with a competent knowledge of the mathematics, and particularly devoted to the study of music, on the theory and practice of which he published several treatises. Vincenzo had three sons, Galileo, Michel Angelo, and Benedetto, and the same number of daughters, Giulia, Virginia, and Livia; but he was not opulent, and being burdened with a numerous family, was unable to provide for them expensive instructors. The subject of this notice exhibited early symptoms of an active and original mind, and even in his childhood showed a singular aptitude for mechanical contrivances, imitating with infinite address all sorts of machines, inventing new ones, or when, as often happened, he wanted the necessary materials for constructing these, adding new pieces to old ones. It is worthy of observation, that the boyhood of his great follower, Newton, whose genius in many respects closely resembled his own, was marked by a similar talent. Galileo commenced his literary studies at Florence, where his family resided; but, for the reason already stated, his masters were of the humblest kind. Knowing the disadvantages of his situation, however, Galileo resolved to supply by industry the want of better opportunities; and he applied with so much assiduity to the study of the classic models, that he soon laid the foundations of that extensive and solid literature to which he was afterwards indebted for the purity of his language and the elegance of his writings. His leisure hours were applied to the cultivation of music and drawing, in both of which arts he excelled. For the former he inherited his father's talent, which he displayed by performing skilfully on several instruments, especially the lute; and during the whole of his life this continued to be his favourite recreation amidst more serious pursuits. In the latter, which he had at one time thoughts of cultivating as a profession, he acquired so perfect a taste, that eminent contemporary artists did not scruple to own their obligations to him for his counsel and suggestions. Such was Galileo at the age of eighteen, when his father, becoming daily more sensible of the extent of his genius, determined, at whatever sacrifice, to give him the advantage of an university education. In 1581 he accordingly commenced his academical career in the university of Pisa, which he entered with the intention of studying medicine, from the profession of which his father hoped that he might one day procure an easy and honourable subsistence. And, that he might not lose any kind of instruction which was to be obtained, he attended a course of peripatetic philosophy, such as it was then taught, in addition to that of medicine. But, called by the predestination of genius to unveil to mankind those wonders of nature, which their fanatical confidence in the opinions of Aristotle prevented them from seeing even when revealed, he could not bring himself to assent without conviction, nor to admit the authority of a master in questions which reason and experiment ought alone to decide. Actuated by this spirit, he several times ventured, in the academical discussions, to combat the firmest supporters of the Aristotelian dogmas, and in consequence he obtained the reputation of possessing an obstinate and contradictory disposition; for men do not easily reconcile themselves to the subversion of opinions, the stability of which they have long been accustomed to consider as incapable of being shaken; and hence the partisans of Aristotle found as great difficulty in doubting as Galileo did in admitting the authority of that master. It is not a little remarkable that, some years later, Descartes commenced in France, as Bacon did in England, the same war which Galileo had so boldly declared at Pisa; thus proving that the great regenerative efforts of the human mind are inevitably brought on by the force of circumstances and the natural progress of ideas, and that the men of genius who attach their names to these memorable revolutions, are themselves carried onward by their age, and precede it only by a few steps.
It was at this period, 1582, when he had scarcely completed his eighteenth year, that Galileo made the first and perhaps the finest of his discoveries. Happening one day to be in the metropolitan church of Pisa, he remarked the regular and periodic movement of a lamp suspended from the roof of the cathedral; he also observed the equal duration of its oscillations, whether great or small; and this he confirmed by repeated experiments. Having satisfied himself as to the phenomenon itself, he immediately perceived the use to which it might be applied for the exact measurement of time; and this idea having remained in his mind, he employed it fifty years afterwards (in 1633) for the construction of a clock intended for astronomical observations. In what manner this instrument was constructed, does not exactly appear; but it seems certain that it was employed for the purpose stated; and this, in our opinion, is sufficient to entitle Galileo to the honour of having been the first to make an application which afterwards became of so much importance to astronomy; for Huygens, who, in truth, rendered it incomparably more perfect, by employing the pendulum as the regulator of clocks, and not as the motive power alone, did not publish his researches on this subject until about the year 1658.
At the time of which we are here speaking, Galileo had no knowledge of the mathematics, nor even the least desire to learn them, not conceiving in what respect triangles
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1 In the matriculation lists of Pisa he is styled Galileo, the son of Vincenzo Galilei, a Florentine, scholar in arts. His entry is dated the 5th November 1591. Galileo and circles could conduce to the advancement of philosophy. The study of geometry was then at a very low ebb, not only in Italy, but in every country of Europe. Commandine, it is true, had recently revived a taste for the writings of Euclid and Archimedes; Vieta, Tartalea, and others had made considerable progress in algebra; and Guido Ubaldi and Benedetti had done something towards establishing the principles of statics, the only branch of mechanics as yet cultivated. But, with these exceptions, the application of mathematics to the phenomena of nature was scarcely thought of. Galileo's first inducement to acquire a knowledge of geometry arose from his partiality for music and drawing; he had heard his father repeatedly state, that these arts, of which he was passionately fond, had their principles in the relations of numbers and of position taught by the mathematics; and he now entreated to be instructed in a subject which promised to unfold to him the true theory of his favourite pursuits. But his father, apprehensive that a study which so strongly attaches those who take pleasure in it would diminish his zeal for medicine, told him to wait until he had completed his course. Galileo, however, was not satisfied; and as Otilio Ricci, professor of mathematics in the university, frequently visited at his father's house, he besought this person to give him secretly some lessons in geometry. The professor consented, after having privately asked and obtained the consent of the father. But the young man had no sooner entered into that field of investigation for which nature had destined him, than his mind became engrossed by the pleasure he felt in the certain and entire possession of truth; from that moment medicine and philosophy were abandoned for Euclid; and all the efforts and remonstrances of his father, who desired to recall him to pursuits which he thought more useful, and even went so far as to prohibit him from holding any intercourse with Ricci, proved unavailing. The impulse had been given, and all attempts to counteract it were fortunately useless.
Galileo had learned enough to study alone. He accordingly continued in secret the perusal of Euclid, at the same time keeping open beside him a Galen or an Hippocrates, in order to conceal the favourite book when his father entered. Having thus by stealth advanced as far as the sixth book, and being transported with the utility which he discovered in the science of geometry for giving force and method to the understanding, he resolved to avow his progress to his father, and entreat the latter no longer to oppose the decided bent of his mind. Vincenzo, perceiving that he was born for the mathematics, yielded to the irresistible predilection of his son, and permitted him to enter freely upon those speculations to which he thenceforward devoted all the energies of his highly-gifted intellect.
Having thus abandoned medicine, Galileo read with avidity the works of the ancient geometers, and then proceeded to study the treatise of Archimedes on floating bodies, which greatly delighted him. He now sought to multiply the applications of the method employed by the illustrious ancient in determining the proportions of an alloy of silver and of gold by successive weighings in water and in air; and for this purpose he invented an instrument similar in its uses to that which was afterwards called the hydrostatic balance. This invention, joined to his previous discovery respecting the movement of oscillation, and his new and free method of discussing subjects in philosophy, had already procured him considerable reputation, when he formed a connection with the Marquis Guido Ubaldi, then one of the most learned mathematicians of Italy. At the suggestion of this distinguished person, Galileo applied himself to consider the position of the centre of gravity in solid bodies; a choice of subject sufficiently indicating the estimate which Ubaldi had formed of his powers, considering that the question was one on which Commandine had recently written, and which at that time engaged the attention of geometricians of the highest order. Galileo, however, discontinued his researches on meeting with Valerio's treatise upon the same subject; but Ubaldi was so much struck with the genius displayed in the essay which Galileo presented to him, that he introduced the young geometer to his brother the Cardinal del Monte, who again warmly recommended him to John de' Medici and the Grand Duke Ferdinand of Tuscany, as a person of the highest promise. These illustrious personages gave him a most favourable reception, and soon afterwards bestowed on him the chair of mathematics in the university of Pisa, although he had as yet scarcely completed his twenty-fifth year.
Excited by this distinction, Galileo neglected nothing calculated to justify the preference which had been given him; and conceiving that a knowledge of the laws of motion is the basis of all solid study of nature, he undertook to establish them, not by hypothetical reasonings, as was the practice in the schools, but by real experiments. He thus demonstrated that all bodies, whatever be their nature, are equally affected by gravity; and that, if the spaces through which they descend in equal times are different, this depends on the unequal resistance opposed to them by the air, according to their different volumes. This important proposition Galileo completed long afterwards, in a work entitled Dialoghi delle Scienze Nuove, in which he established the true theory of uniformly accelerated motion. The novelty and beauty of his first experiments, performed before an immense concourse of spectators, excited great enthusiasm. But they at the same time embittered the animosity of the partisans of the ancient philosophy, who, seeing their whole science attacked, sought to destroy the innovator in the opinion of persons in power, and at length succeeded in raising against him such a host of annoyances and persecutions, that, in 1592, he was obliged to resign his chair at Pisa. He returned to Florence without employment, but durst not present himself in the house of his father, who had already made so many sacrifices on his account. He had the good fortune, however, to obtain from Guido Ubaldi a letter of recommendation to an opulent gentleman of Florence, of the family of the Salviati, who received him with extreme kindness, and afforded him the means of prosecuting his discoveries, until he could find some employment. With a view to serve him, Salviati also made him known to a Venetian nobleman of the name of Sagredo; an enlightened and influential man, who soon afterwards obtained for the youthful philosopher the chair of mathematics at Padua, which was conferred on him for six years. It was in gratitude for these seasonable benefits that Galileo gave the names of Sagredo and Salviati to the two interlocutors in his dialogues who support the true philosophy.
In his new situation, where he enjoyed greater freedom than he had done at Pisa, Galileo continued, with still more brilliant success, both his public lessons and his experimental researches. He constructed, for the service of the state, various machines of great utility; and he wrote for his pupils treatises on gnomonics, mechanics, spherical astronomy, and even fortification, according to the usage of the age, when many things were united which the progress of knowledge has since separated. In 1597, he invented the thermometer and the proportional compass or sector, which he called the military compass, because he had principally in-
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1 The original idea of this instrument belongs to the Greek mathematician Hero; and even Santorio, who has been named by Italian writers as the inventor, and, at one time, claimed the invention as his own, refers it to him. In 1613, Sagredo, who has been Galileo tended it for the use of engineers. In 1599, his commission having expired, the senate renewed it for another six years, with an increase of salary, which Galileo repaid to the republic by new discoveries. In 1604, an unknown star of extraordinary brightness having suddenly appeared in the constellation of Serpentarius, Galileo demonstrated, by his observations, that this body was placed far beyond what the peripatetics called the elementary region; nay, that it was much more remote than all the planets, contrary to the formal and infallible opinion of Aristotle, who maintains that the heavens are incorruptible and free from all mutation. He also made researches on natural magnets, and succeeded in considerably augmenting their power by means of capping or casing them. His commission as professor was renewed a second time in 1606, with additional advantages, for which he testified his gratitude, as before, by increased diligence in the prosecution of his discoveries.
But envy, which had never lost sight of him, exerted herself to disturb that peace which is so necessary to the successful pursuit of science. In 1604, on the occasion of his researches respecting the new star, he had been grossly abused by one Baltasar Capra of Milan. This man had the audacity to publish a Latin treatise on the proportional compass, in which he represented himself as the real inventor of that instrument; but the calumny was so gross that nobody was deceived by it; Galileo confounded his adversary, and the work of Capra was prohibited as a defamatory libel. Nor was this the only instance in which he had to vindicate his right of property in his own inventions. He frequently found himself ill-compensated for the readiness with which he communicated the results of his investigations; but he always raised himself by new discoveries, far above these disgraceful attempts to appropriate the fruits of his genius.
The year 1609 was signalised by a discovery on the part of Galileo, which forms one of the most solid monuments of his glory. In the month of April or of May, a rumour was circulated in Venice that a Dutchman had presented to Count Maurice of Nassau an instrument, by which means distant objects appeared as if they were near at hand. On this slight and cursory hint Galileo immediately applied himself to discover whether the thing was possible, conformably with the passage of the luminous rays through spherical glasses of various forms. Some attempts made with lenses which he had at hand produced the desired effect; and next day he gave an account of his success to his friends, which, in fact, was nothing less than the invention of the telescope. A short time afterwards he presented several of these instruments to the senate of Venice, accompanied with a description in which he unfolded the immense consequences for nautical and astronomical observations which would certainly result from the discovery; and in recompense of his ingenuity his commission as professor was continued for life, with an allowance of salary triple that which he had previously received. Galileo neglected nothing calculated to evince his gratitude, or to add to the claims which had merited these favours. Indefatigable in his researches, he invented the microscope; he also improved his telescope, and soon brought it to a state fit to be applied to the observation of the heavens. He then perceived what as yet no mortal eye had ever seen; the surface of the moon, like that of the earth, bristled with high mountains and ploughed with deep valleys; Venus, presenting, like the moon, phases which prove her rotundity; Jupiter environed with four satellites, who accompany him in his course; the milky way; the nebulæ; in a word, the whole heavens bespangled with a countless multitude of stars too small to be even perceived by the naked eye. It is more easy to conceive than describe the surprise and delight which the first view of so many wonders must have inspired him within, as well as the admiration which they could not fail to produce when they were known. A few days having sufficed to pass them in review, he hastened to announce his observations to the world in a publication entitled Nuncius Sidereus, or Celestial Courier, which he dedicated to the princes of Medici, and which he continued at intervals, in proportion as he discovered new objects. He also observed that Saturn sometimes appeared under the form of a simple disc, and sometimes with two appendages which seemed two small planets; but it was reserved for another astronomer (see Huygens) to demonstrate that these appearances were produced by the ring with which Saturn is surrounded. Galileo also discovered moveable spots on the globe or disc of the sun, whom the peripatetics had declared incorruptible, and did not hesitate from these to infer the rotation of that planet. He remarked that feeble light which, in the first and last quarter of the moon, renders visible, by means of the telescope, the part of her disc which is not then directly enlightened by the sun; and he concluded rightly that this effect was owing to the light reflected towards the moon by the earth. The continued observation of the spots of the moon satisfied him that that planet always presents nearly the same aspect; but in these he nevertheless recognised a species of periodic oscillation, to which he gave the name of libration, the exact laws of which were afterwards made known by Dominic Cassini. In a word, not less profound in following new truths to their consequences than subtile in discovering them, Galileo perceived the use to which the motions and eclipses of the satellites of Jupiter might be turned for the measure of longitudes; and he even undertook to make a sufficient number of observations of these stars to enable him to construct tables for the use of navigators.
After so many and so admirable discoveries, we have good reason to be astonished that any one should dream of denying to Galileo the invention of the telescope, with which he had made them; as if, in such a case, the inventor was not he who, guided by certain rules and by great views, knew how to perform wonders with that which chance had thrown rude and unfinished into incapable hands. If he who, in Holland, accidentally joined two glasses of unequal curvature, was really the inventor of the telescope, why then did he not turn it towards the heavens, the most beautiful and sublime application of that instru-
already mentioned as the friend of Galileo, writes to him in the following terms:—"I have brought the instrument which you invented, into several convenient forms, so that the difference of temperature between two rooms is seen as far as a hundred degrees." The date of this communication, which incidentally establishes the invention of Galileo, is anterior to the claims of Santorio, and also to those of Drebbel, a Dutch physician, who obtained, and still preserves in Germany, the honour of having invented this instrument. Another testimony may be added. In 1638, Castelli wrote to Cesariani that he remembered an experiment shown to him more than thirty years before by Galileo, who took a small glass bottle, about the size of a hen's egg, the neck of which was twenty-two inches long and as narrow as a straw. "Having well heated the bulb in his hands, and then introduced its mouth into a vessel containing water, he withdrew the handle from the bulb, in which the water rose in the tube higher than eleven inches above the level of that in the vessel; and this principle he employed in the construction of an instrument for measuring heat and cold." Galileo's thermometer, therefore, consisted merely of a glass tube ending in a bulb, the air in which, being partly expelled by heat, was replaced by water from a glass in which the open-end of the tube was immersed; and the different degrees of heat were indicated by the expansion of the air which still remained in the bulb, so that the scale would be the reverse of that now in use, as the water would stand at the highest level in the coldest weather. In other words, it was a compound of the barometer and thermometer. Galileo. Why did he leave to Galileo the happiness and glory of overturning, in the eyes of all, ancient prejudices, of consolidating by the clearest proofs the system of Copernicus, and of aggrandising the celestial spaces beyond all that the imagination could have conceived? But however this may be, it is easy to comprehend to what a height so many and so great discoveries must have raised the views of Galileo; he perceived all the consequences which resulted from them relatively to the constitution of the universe; and, indeed, how could they escape him who, having taken nature as his guide, had, during his whole life, preserved his mind open to her impressions? He concealed none of these high consequences, which formed as it were the soul of his writings and conversation; and he considered himself henceforth entitled to despise errors too gross to be honestly maintained.
But, unfortunately for himself, he was no longer under the protection of Venice. Yielding to the instances of the Grand Duke of Tuscany, who had named him mathematician extraordinary, and loaded him with favours, he had quitted Padua, where he enjoyed the utmost freedom, for Florence, where such a thing as liberty was scarcely known. Honoured by the senate of Venice, and united by the ties of friendship with several of the most distinguished senators, he could publish his opinions without danger to himself as long as he remained within the territories of that state. But, in the end, experience proved that he could have no such security at the court of a prince, obliged at least to keep up appearances with the court of Rome. Besides the number of envious persons whom his great merit had exasperated against him, his discoveries made him enemies of all those who had hitherto taught the ancient doctrines; and of these persons by far the greater part were ecclesiastics. Accordingly, some spread it abroad that his discoveries in the stars were pure visions, comparable only to the voyage of Astolpheus; others affirmed that they had had the telescope in their possession during entire nights, and that they had seen nothing of all that which Galileo had announced; and a preacher was found who, malicious enough to convey a dangerous allusion in a pun, took as his text the words of the Gospel, *Viri Galilei, quid statis adspicientes in caelum?* It was thus that the countrymen of Copernicus had publicly ridiculed him on the stage; and it was thus that, at a later period, the reformed of Holland persecuted Descartes, who had taken refuge amongst them.
But the most certain method of reaching Galileo was to begin by prohibiting the doctrine of Copernicus, which he supported and propagated with so much distinction. This was accordingly effected by representing it as contrary to Scripture, and denouncing it to the holy see. Galileo endeavoured in vain to allay the storm, by publishing, in 1616, a letter addressed to the Grand Duchess of Tuscany, in which he undertook to prove theologically, and by reasons deduced from the Fathers, that the terms of Scripture might be reconciled with his new discoveries respecting the constitution of the universe. But this production only afforded a new handle to his adversaries, who maintained that he had rested his defence on an opinion which was itself erroneous in point of doctrine. He was cited to appear personally at Rome, and constrained to repair thither to defend himself. But neither the arguments which he urged in support of his opinions, nor the justice which they were forced to render to his knowledge, his merit, and even his catholicity, could prevent an assembly of theology, named by the pope, from coming to the following conclusion: "To maintain that the sun is placed immovable in the centre of the world, is an opinion absurd in itself, false in philosophy, and formally heretical, because it is expressly contrary to the Scriptures; to maintain that the earth is not placed in the centre of the world, that it is not immovable, and that it has even a daily motion of rotation, is also an absurd proposition, false in philosophy, and at least erroneous in point of faith." Confounded at this deliverance, Galileo employed all the arguments which the truth suggested to him in defence of a doctrine which his observations had rendered indubitable; but his efforts were unavailing; his reasonings were disregarded; and as he had not showed sufficient deference to the decision of the holy office, he was personally interdicted from professing in future the opinion which had just been condemned.
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1 "The interpreter of the works of nature is experiment," says Leonardo da Vinci: "that is never wrong: it is our judgment which is sometimes deceived, because we expect results which experiment refuses to give. We must consult experiment, and vary the circumstances, till we have deduced general rules, for it alone can furnish us with them. But, it will be asked, what is the use of these general rules? I answer, that they may direct us in our inquiries into nature and the operations of art. They keep us from deceiving ourselves and others, by promising ourselves results which we can never obtain." (Venturi, Essai sur les Ouvrages de Léonardo da Vinci.)
2 It has been contended that the treatment which Galileo experienced on this and a subsequent occasion was caused, not by his maintaining the true system of the world, which, in the above declaration, is formally condemned as "false in philosophy and erroneous in faith," but solely by his persisting in the endeavour to prove that the Scriptures were reconcilable with the Copernican theory. "Ce philosophe (Galileo)," says Bergerie, "ne fit point persécute comme bon astronome, mais comme mauvais théologien. C'est son entêtement à vouloir concilier la Bible avec Copernic, qui lui donna les juges." Mais vingt auteurs, surtout parmi les Protestants, ont écrit que Galilée fut persécuté et imprisonné pour avoir soutenu que la terre tourne autour du soleil, que ce système a été condamné par l'Inquisition comme faux, erroné, et contraire à la Bible." (Encyclopédie Méthodique, art. Sciences humaines, Paris, 1790.) This is a complete misrepresentation of facts known to every one. So far was Galileo from persisting in an attempt to reconcile the Bible with Copernicus, that he regarded this as a matter altogether indifferent, and indeed beside the real question. "I am inclined to believe," says he in his letter to the Grand Duchess of Tuscany, "that the intention of the sacred Scriptures is to give mankind the information necessary for their salvation, and which, surpassing all human knowledge, can by no other means be accredited than by the mouth of the Holy Spirit. But I do not hold it necessary to believe that the same God who has endowed us with senses, with speech, and with intellect, intended that we should neglect the use of these, and seek by other means for knowledge which they are sufficient to procure us; especially in a science like astronomy, of which so little notice is taken in the Scriptures, that none of the planets, except the sun and moon, and once or twice only Venus, under the name of Lucifer, are so much as named there. This therefore being granted, I think that the discussion of natural problems we ought not to begin at the authority of texts of Scripture, but at sensible experiments and necessary demonstrations; for from the divine word sacred Scripture and nature did both alike proceed; and I conceive that, concerning natural effects, that which is most sensible experiences acts before our eyes, or necessary demonstrations prove unto us, ought not upon any account to be called in question, much less condemned, upon the testimony of Scripture texts, which my under their words couch senses seemingly contrary thereto." Can anything be more explicit than the contradiction of the assertion of Bergerie contained in these words? Is there any evidence here of Galileo's alleged "entêtement à vouloir concilier la Bible avec Copernic?" But the philosopher proceeds in continuation: "Again, to command the professors of astronomy that they of themselves should see to the confuting of their own observations and demonstrations, is to enjoin a thing beyond all possibility of being done; for it is not only to command them not to see that which they do see, and not to understand that which they do understand, but it is to order them to seek for and find the contrary of that which they happen to meet with. I would entreat these wise and prudent fathers that they would with all diligence consider the difference which exists between opinionative and demonstrative doctrines; to the end that, well weighing in their own minds with what force necessary inferences urge... Galileo returned to Florence in 1617, and resumed, with what grief may be easily imagined, the course of his astronomical labours. But his love for these sublime truths, of which he considered himself as the depositary, increasing in proportion to the efforts made to extinguish it, he undertook to silence, if he could not persuade, his adversaries, by collecting into a body all the physical proofs of the motion of the earth and the constitution of the heavens; and during sixteen entire years he was engaged in this work. All that the finest genius could imagine in point of ingenuity, or the purest taste admit in point of elegance, he employed to render the truth attractive. But it is not a learned treatise which he presents to us as the fruit of his labour and talents; it is merely a continued simple dialogue between two of the most distinguished personages of Florence and Venice, and a third interlocutor, who, under the name of Simplicius, undertakes to re-produce the "invincible arguments" of the peripatetics; and each perfectly sustains the part assigned to him. The two men of the world possess instruction, without system, and without prejudices; they discuss, examine, propose doubts, and only yield to cogent reasons. The good Simplicius, on the other hand, is altogether scholastic; he neither understands nor desires to comprehend any thing but Aristotle; he judges things true or false according as they are conformable or opposed to the assertions of his master; the least pleasantry on this subject is insupportable to him, and he yields not to any kind of conviction. The style of each of the interlocutors is also perfectly adapted to his character, without ceasing however to preserve, amidst these shades of distinction, an exquisite elegance, united with the most felicitous choice of expressions.
But if great genius was required for the composition of such a work, equal address was necessary to obtain permission to publish it; and this Galileo undertook to procure even in Rome itself. In 1630 he proceeded to that city, and having waited on the master of the sacred palace, boldly presented his work as a collection of new scientific fancies, at the same time requesting him to have the goodness to examine it scrupulously, to retrench whatever might appear to him exceptionable, and indeed to criticise it with the greatest severity. The prelate, not suspecting anything, read it once and again; handed it to one of his colleagues for his opinion; and, not seeing anything reprehensible in the work, set his hand to the most ample approbation of its contents. But the permission thus obtained was not sufficient; for, in order to profit by it, the work must be printed at Rome; and the numerous enemies of Galileo in that city would not have failed to explode the mine which the philosopher was himself charging to blow them up. On the pretext of some difficulty of communication between Rome and Florence, occasioned by a contagious distemper which then prevailed, Galileo accordingly wrote to the master of the sacred palace, soliciting permission to print his work at Florence, on the condition of having it again examined in that city. But the prelate, who perhaps began to suspect some deception, made difficulties; pointed out to Galileo a new censor; and demanded to see the approbation which he had previously given, in order, as he said, to revise the terms in which it had been conceived. With this request Galileo could not refuse to comply; but the prelate having once got hold of the document, refused to restore it, or to give any answer in explanation of his conduct; so that Galileo, after making every effort to recover it, and even causing it to be demanded by the ambassador of Tuscany, was compelled to abandon the pursuit as hopeless; and, contenting himself with the approbation of the censor of Florence, which he now managed to obtain, he published his work in 1632.
To shield himself as much as possible from prosecution, he however imagined the singular expedient of presenting his dialogues to the public as an apology for the judgment of Rome, by which the doctrine of Copernicus had been condemned. "Some years ago," says he, in the commencement of the introduction, which is addressed to discreet readers, "a salutary edict was promulgated at Rome, which, in order to obviate the perilous scandals of the age, enjoined an opportune silence as to the Pythagorean opinion of the earth's motion. There were not wanting persons who rashly asserted that this decree had originated, not in a judicious examination, but in ignorance and passion; and complaints were even heard that councillors unexperienced in astronomical observations should have attempted by hasty prohibitions to clip the wings of speculative minds. When I heard these rash lamentations, my zeal would not suffer me to remain silent; and being fully informed in regard to that most prudent determination, I thought it proper to appear publicly on the theatre of the world as a witness of the actual truth. I happened at that time to be in Rome; I was admitted to the audiences, and enjoyed the approbation, of the most eminent prelates of that court; nor did the publication of the decree pass without my receiving some previous intimation of the circumstance. Wherefore it is my intention, in this present work, to show to foreign nations that as much is known of this matter in Italy, and particularly in Rome, as ultramontane diligence ever formed any notion of; and, collecting together all my own speculations on the Copernican system, to give them to understand that the knowledge of those preceded the Roman censures, and that from this country proceeded not only dogmas for the salvation of the soul, but also ingenious discoveries for the gratification of the understanding. With this object in view, I have taken up in the dialogue the Copernican side of the question, treating it as purely a mathematical hypothesis, and endeavouring in every artificial manner to represent it as having the advantage, not over the opinion of the stability of the earth absolutely, but according to the manner in which that opinion is defended by some who indeed profess to be peripatetics, but retain only the name, and are contented without improvement to worship shadows, not philosophizing with their own reason, but only from the recollection of four
us, they might the better assure themselves that it is not in the power of professors of demonstrative sciences to change their opinions at pleasure, and adopt first one side and then another; and that there is a great difference between commanding a mathematician or a philosopher, and the disposing of a lawyer or a merchant; and that the demonstrated conclusions touching the things of nature and of the heavens cannot be changed with the same facility as the opinions are what is lawful or not in a contract, bargain, or bill of exchange. Therefore, first let them men apply themselves to examine the arguments of Copernicus and others, and leave the conclusion of them as erroneous and heterodox to whom it belongs; yet let them not hope to find such rash and precipitate determinations in the judicious and holy fathers, or in the absolute wisdom of him who cannot err, as those into which they suffer themselves to be hurried by some particular afflition or interest of their own. In these and such other positions, which are not directly articles of faith, no man doubts but his holiness has always an absolute power of admitting or condemning them; but it is not in the power of any creature to make them to be true or false, otherwise than of their own nature and in fact they are."
Delambre, whose prejudice against Galileo is as unreasonable as his partiality to Kepler is marked, quotes this sentence as an instance of mis-statement of facts on the part of Galileo. With all his acknowledged ability, the historian of astronomy does not seem to have perceived, what must be obvious to almost every reader, that the whole passage is ironical, and that in the very sentence which he has cited there lurks a bitter sarcasm. (Histoire de l'Astronomie Moderne, tome i. p. 666.) principles imperfectly understood." Any one who peruses a few pages of the dialogues will be at no loss how to interpret this declaration, nor will he feel any surprise that those whom Galileo here pretended to vindicate should have evinced but little gratitude for such a justification. But what can scarcely be imagined now, is the fury which the appearance of this work excited amongst the theologians of Rome, almost all of whom were ardent peripatetics. In vain did Galileo attempt to escape by alleging that his book had been submitted to the judgment of the holy see; in vain did he, as a last resource, protest that his only object had been to expound, in a philosophical manner, the two systems of Ptolemy and Copernicus. His enemies would not suffer any such excuse to be listened to. Still there remained to him some hope, founded upon the personal esteem of Pope Urban VIII., who, on a former occasion, had given him a most gracious reception, and had even paid his astronomical discoveries the compliment of celebrating them in bad verse; but the holy father having been persuaded that Galileo had intended to represent him under the character of Simplicius, his wounded self-love rendered his severity inexorable. Notwithstanding the intercession of the Grand Duke of Tuscany, and the earnest solicitations which this prince caused to be made by his ambassador, the work of Galileo was delayed to the Inquisition, and the author himself ordained to appear before that formidable tribunal.
The power of Rome was then supreme; it was necessary to obey. Neither the infirmity of his health, nor the pain he suffered from a rheumatic complaint which afflicted him, could procure an exemption from that sorrowful journey. This was in 1633, Galileo being then in the sixtieth year of his age. "I arrived at Rome," says he, in one of his letters, "on the 10th February, and was committed to the clemency of the Inquisition, and of the sovereign pontiff, Urban VIII., who had some esteem for me, although I could not compose epigrams or write little amatory sonnets. I was put under arrest in the delicious palace of the Trinità de' Monti, the residence of the ambassador of Tuscany. Next day I received a visit from Father Lancio, commissary of the holy office, who took me with him in his coach. By the way he put to me a number of questions, and showed a great desire that I would repair the scandal which I had given to all Italy by maintaining the opinion of the motion of the earth; and to all the mathematical reasons which I could oppose to him, he could make no other answer than this: Terra autem in eternum stabit, quia terra in aeternum stat. In discoursing thus we arrived at the palace of the holy office. I was presented by the commissary to the assessor, with whom I found two religious Dominicans, who civilly informed me that I would be permitted to explain my reasons before the congregation, and that afterwards I should be heard as to my grounds of excuse, if I was found guilty. The Thursday following I appeared before the congregation, and applied myself to the exposition of my proofs. But, unfortunately for me, they were not apprehended; and, notwithstanding all the pains I took, I could not succeed in making myself understood. My reasonings were cut short by bursts of zeal; they spoke to me only of the scandal which I had occasioned; and always opposed to me the passage of Scripture on the miracle of Joshua as the victorious piece of my process. This brought to my recollection another passage where the language of the sacred book is evidently conformable to popular ideas, since it is said that the heavens are solid, and polished like a mirror of brass. This example appeared to me one in point to prove that the expression of Joshua might be similarly interpreted; and the consequence seemed to me perfectly just. But no regard whatever was paid to it; and all the answer I received consisted of shrugs of the shoulders."
On the 30th of April Galileo was sent back to the residence of the ambassador, with a prohibition not to go beyond the encinte of the palace, but with permission to walk freely in the extensive gardens attached to it. On the 22d of June he was again brought before the tribunal to hear the sentence read, and pronounce the abjuration dictated to him, according to which the venerable philosopher was made to say, "I abjure, curse, and detest the error and heresy of the motion of the earth," &c. and to promise that he would never more in future say or assert any thing, verbally or in writing, importing "that the sun is the centre of the world, and immovable; and that the earth is not the centre of the world, and moveable." This expiation being completed, his dialogues were prohibited; he was condemned to suffer imprisonment for an indefinite period; and, as a salutary punishment, he was ordained to recite once a week for three years, the seven penitential psalms. Such was the unworthy recompense of one of the greatest geniuses that has ever enlightened humanity.
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1 See Letter written by Galileo from Acastri, 26th June 1636, and cited by Targioni-Tozzetti in his History of the Sciences in Tuscany, tome ii. p. 147. 2 Letter of Galileo, cited by Tiraboschi. 3 The sentence of the Inquisition on Galileo, one of the most remarkable records of intolerant ignorance and bigoted folly to be found in the history of science, is conceived in the following terms:—We, the undersigned, by the grace of God, cardinals of the Holy Roman Church, Inquisitors General throughout the whole Christian Republic, Special Deputies of the Holy Apostolical Chair against heretical depravity: Whereas you, Galileo, son of the late Vincenzo Galilei of Florence, aged seventy years, were denounced in 1615 to this holy office, for holding as true a false doctrine taught by many, namely, that the sun is immovable in the centre of the world, and that the earth moves, and also with a diurnal motion; also, for having pupils whom you instructed in the same opinions; also, for maintaining a correspondence on the same with some German mathematicians; also, for publishing certain letters on the solar spots, in which you developed the same doctrine as true; also, for answering the objections which were continually produced from the holy Scriptures, by glazing the said Scriptures according to your own meaning; and whereas thereupon was produced the copy of a writing, in form of a letter, professedly written by you to a person formerly your pupil, in which, following the hypothesis of Copernicus, you include several propositions contrary to the true sense and authority of the holy Scripture; therefore this holy tribunal, being convened together against the disorder and mischief which was then proceeding and increasing, to the detriment of the holy faith, by the desire of his holiness and of the most eminent lords cardinals of this supreme and universal Inquisition, the two propositions of the stability of the sun, and motion of the earth, were examined by the theologians qualified as follows:—The proposition that the sun is in the centre of the world, and immovable from its place, is absurd, philosophically false, and formally heretical, because it is expressly contrary to the holy Scripture; 2dly, the proposition that the earth is not the centre of the world, nor immovable, but that it moves, and also with a diurnal motion, is also absurd, philosophically false, and, theologically considered, at least erroneous in faith. But whereas being pleased at that time to deal mildly with you, it was decreed in the holy congregation held before his holiness on the 25th day of February 1616, that his eminence the Lord Cardinal Bellarmine should enjoin you to give up altogether the said false doctrine; if you should refuse, that you should be ordered by the commissary of the holy office to relinquish it, not to teach it to others, nor to defend it, nor ever mention it, and in default of acquiescence that you should be imprisoned; and in execution of this decree, on the following day, at the palace, in presence of his eminence the said Lord Cardinal Bellarmine, after you had been mildly admonished by the said lord cardinal, you were commanded by the acting commissary of the holy office, before a notary and witnesses, to relinquish altogether the said false opinion, and in future neither to defend nor teach it in any manner, neither verbally nor in writing; and upon your promising obedience you were dismissed. And in order that so pernicious a doctrine might be altogether rooted out, nor insinuate itself farther to the heavy detriment of the Catholic truth, a decree emanated from the holy congregation of the index prehi- Galileo, as he rose from the kneeling posture, indignant at the monstrous injustice of his age, stamped on the ground, and said in an undertone, *E pur si muove*, It moves notwithstanding. No doubt it does move, and this is the only answer which those who study nature should at all times make to their detractors and persecutors. What signifies the opinion of men when nature herself speaks? Of what value are their prejudices, or even their wisdom, in opposition to her laws? Why denounce as an impiety the observation of the works of God? Such, indeed, are now the sentiments of persons the most enlightened on the subject of theology; the motion of the earth and the immobility of the sun are no longer contrary to the words of Scripture; it is at length admitted that the Holy Spirit spoke to men in the only language which they could comprehend. It is true that this interpretation, which is now universally received, did not appear good in the time of Galileo, since we have seen that he was himself reprehended for having attempted to give it effect; but, from what we have related of the history of his life, it is evident that the persecution exercised against him was the effect, unhappily too common, of the envy which always attaches to great celebrity. There are arms peculiar to every country. Galileo was a heretic in Italy, as Descartes was an atheist in Holland. However, in denouncing to posterity the shameful injustice done to this great man, it must in fairness be admitted that the formidable tribunal by which he was condemned did not exercise towards him its extreme severity. It has been pretended, without any probability, that he was put to the question. But although it is true that, in the inquisitorial style, this seems to be indicated by the words *rigorosum examen* which are found in the text of the judgment, and although, by a singular coincidence, he began about this time to be afflicted with an intestinal hernia, the ordinary consequence of the particular species of torture (*il tormento della corda*) to which he is supposed to have been subjected; yet, for the honour of humanity, these presumptions... tions seem completely destroyed by the conduct which was subsequently observed towards him. It is certain, from the letters of the ambassador of Tuscany, that he was not thrown into the dungeons of the holy office, although the judgment bears so. The prison assigned him was the lodging of one of the superior officers of the tribunal, with permission to walk throughout the whole palace; he was allowed to retain his domestic; and, so far from being put in solitary confinement, he was permitted to receive the visits of his friends as often as he pleased. All this is established by numerous letters of Galileo himself, dated at this period, and which, fortunately for the cause of truth and humanity, have been preserved. If he did not at once recover his entire liberty, his captivity was at least mitigated as much as it could well be, since the prison assigned him was the magnificent palace of the Archbishop of Sienna, Piccolomini, his friend and pupil, surrounded with beautiful gardens, in which he was allowed to take exercise at pleasure. In the beginning of December 1633, the pope granted him permission to reside openly in the country near Florence; and at a somewhat later period, he was allowed to enter the city as often as his infirmities required. Nevertheless, these restrictions prove that he still remained under the surveillance of the Inquisition; and the Italian writers even say that he several times received, from that tribunal, threatening letters, on account of the pursuits to which he still applied himself; and on pretence of the too intimate connection which he maintained with the learned in Germany.
It was no doubt too much thus to afflict an old man who had committed no other error than that of unfolding truths previously unknown. This treatment made a deep impression on his mind, as may be seen from the preface to his two new dialogues on the motion and resistance of solids, which he confided in manuscript to the Count de Noailles, when the latter was on his return to France from Rome, where he had been ambassador. "Confounded and afflicted with the bad success of my other works," says he, "and having resolved to publish nothing more, I have wished at least to place in sure hands some copy of my works; and as the particular affection with which you have honoured me will certainly make you desirous to preserve them, I have chosen to confide these to you." The count lost no time in communicating them to the Elzevirs, by whom they were printed at Leyden, in 1628, 4to; and it may be presumed that this publication did not occasion Galileo as much uneasiness as his disciple Viviani, writing, like himself, near Rome, would lead us to believe; a presumption confirmed by several letters, addressed to his intimate friends, which have fortunately been preserved. In these two dialogues Galileo created a science altogether new, namely, that of the resistance of solids; and he established, with admirable sagacity, the laws, not less novel, of the accelerated motion of heavy bodies, whether falling freely through space or descending on inclined planes. Nor is this the only production of Galileo which the French have had the honour of saving from his enemies. It was a Frenchman, Father Mersenne, who first published his mechanics; a book which, in a few pages, contains, among other discoveries, a demonstration of the laws of equilibrium on the inclined plane, and that other principle so fruitful in consequences, since called the principle of virtual velocities, which consists in this, that, in any machine whatsoever, the power and the weight in equilibrio are inversely proportional to the spaces which they would pass through in a time infinitely small, if the equilibrium were ever so little disturbed.
Oppressed with the weight of years and misfortunes, Galileo still pursued his observations, and worked with indefatigable courage to continue his tables of Jupiter's satellites, when the loss of sight obliged him, at the age of seventy-four, to discontinue his labours. But his faculties survived this deprivation, and he did not cease to meditate on nature though it was now concealed from his view. Surrounded by attentive and respectful pupils, and by the most distinguished persons of Florence, he lived four years in this state of blindness, after which a slow fever terminated his long and brilliant career, on the 9th of January 1642 (the same year in which Newton was born), at the advanced age of seventy-eight. His body was transported to Florence, and buried in the church of Santa Croce; but it was not until near a century later that the splendid monument was erected which now covers his remains and those of his celebrated pupil and friend Viviani.
The most masterly, and at the same time the most impartial estimate which has yet appeared of the services rendered to the cause of human knowledge by the Florentine philosopher, will be found in the Third Dissertation prefixed to this work (see particularly p. 469, 470), to which the reader is accordingly referred; more especially with respect to the preference which Biot, supported by Hume, has been pleased to assign to Galileo over Bacon in pointing out the true method of studying nature, and showing the art, if it may be so called, of interrogating her by means of experiment. On this subject Professor Playfair has left little or nothing to be said by those who come after him. The accomplishments of Galileo as a scholar were scarcely less remarkable than his discoveries in science. His style, which has been happily characterised by Hume, is so elegant and pure that it has become a classical authority; and we have already shown by what happy preparation he attained this excellence in the art of writing. He loved literature, especially poetry, and was so passionate an admirer of Ariosto that he knew the whole of the Orlando by heart. This predilection indeed he carried so far as to suffer it to betray him into injustice towards Tasso; at least if we may judge from an early composition published after his death, but which he most probably never intended to see the light. But if the manner in which he speaks of the Jerusalem Delivered be not always consistent with the respect due to so great a poet, something must at the same time be allowed for that freedom with which the mind gives scope to its own impressions when it converses as it were with itself alone, and is not obliged to observe any of those restraints which publication imposes. It is probable that Galileo would have softened his criticism if he had published it; and it may be believed that when his taste was formed, he would have judged it proper to suppress it entirely; for in several passages of his letters he renders justice to the merit of Tasso, although Ariosto always appeared to him superior as a poet. We have entered into this detail, because an interest attaches to all the distinctive characteristics or peculiarities of celebrated men. For the same reason, we shall add, that Galileo was a man of amiable character and agreeable appearance, particularly in his old age; that his temperament was animated, his manners cheerful, and his conversation attractive; and that he preferred living in the country, where his favourite relaxations consisted in the cultivation of his garden, and in the conversation of his friends. He was never married; but he left three natural children, a son, and two daughters, who, after his death, entered a convent, and took the veil.
Without pretending to give an accurate list of all the works of Galileo, we shall content ourselves with the following enumeration of his principal productions:—1. Nuncius Sidereus, Florence, 1610, in 4to, reprinted the same year at Venice in 4to, and at Frankfort in 8vo; 2. Il Saggiatore, nel quale, con bilancia esquista e giusta, si ponderano le cose contenute, &c. Rome, 1623, in 4to, being a refutation of the Libra Astronomica of the Jesuit Grassini; 3. Dialogi quattro sopra i due massimi Sistemi del