(Ζωνος) of Elea, founder of the Eleatic school of speculative philosophy, and inventor, according to Aristotle (Diog. Laërt. and Sextus Emp., Adv. Math.), of the system of Dialectic, was the son of Teleutagoras, and was born at Elea (called also Velia, or Hyele), probably about 495 B.C. He was the pupil and the adopted son of Parmenides, with whom he visited Athens, probably about 454 B.C., if we may trust the Parmenides of Plato, where he is said to have read one of his great works in the hearing of Socrates, then a youth. According to Strabo, Zeno, as well as his master, was engaged in legislating for Elea. He probably lived till somewhere about 435 B.C. The circumstances of his death are variously reported by different writers. They all agree in this, that he conspired against a tyrant of Elea, who put him to death with great torture. Zeno, we are told, was a wise, modest, truthful man. He preferred the society of his quiet little village of Elea to the grandeur and wealth of the city of Athens. Zeno is described by Plato as a tall and handsome man. Plutarch says he was the tutor of Pericles.

The following are the leading doctrines of Zeno, so far as they can be gathered up from the stray fragments of him which now remain, or from the reports of those ancient writers who profess to have studied him. The prose work (συγγραφή) is Plato's word in the Parmenides) which Zeno read at Athens, was written in defence of the doctrines of his master Parmenides, who continued and developed the system of Xenophanes. According to Parmenides, all is one, and unity is the sole existence. If all is one, said the empirical Ionians, then there can be no difference among objects. The like is merely the unlike, the unlike is just the like: the great is the small, and the small is the great; motion is rest, and rest is motion. The Ionians, unfortunately, trusted merely to their senses, which could only give them plurality. They could find no basis for what Xenophanes, Parmenides, and the rest of the absolutists called unity, within the compass of their philosophy. Hence these materialists denied altogether that such an object had any existence, save in the crazed brains of its advocates. Now, how did Zeno reply to such objections? In place of defending his master directly, he attacked his adversaries by turning on them their own arguments, and by ridiculing the sorry figure which they presented, when stripped of what they most valued. He engaged to demonstrate that all the difficulties raised by the partisans of plurality, against the doctrine of unity, not only were quite pointless, but fell directly upon the system which they were meant to defend. From the empirical hypothesis of the Ionians he was prepared to show, that the unlike could be cogently proved to be the like, and the like the unlike,—doctrines which these philosophers thought they could demonstrate from the premises of the Eleatics. That this is the correct view to take of Zeno's polemic is sufficiently established by Plato (Parmenides, Bek., p. 7), and by Simplicius in his commentary on that philosopher. The Ionians could hardly have fared worse at the hands of any of the Grecian sages than they did at the hands of Zeno. He brought a most powerful mind to his task, and, curious to say, subsequent thinkers have very generally agreed in misunderstanding both his reasoning and his method, and it is only of late years that Kant, in his Antinomies of the Pure Reason (see Kritik der Reinern Vernunft) seized upon the much maligned doctrines of the Eleatic, and held them up to the admiration of all true thinkers as rare examples of acute and just thought. Bayle, in a clever paper on Zeno, in his Dictionnaire, makes him, according to custom, a sceptic. Brucker finds that Zeno surpasses his intelligence, and he is content to make him a pantheist. Others, again, have charged him with nihilism. Zeno, fortunately, can afford to sit quite easy to all those affronts offered to his reason. If any objection can be taken to his polemic, it is that he perhaps carries his arguments too far against the existence of empirical sensationalism, which not unlikely raised the idea of his confirmed nihilism in some men's minds.

Here are Zeno's doctrines in brief. He proved irrefragably that unity (or God) is eternal, that it is one, that it is round, that it is neither finite nor infinite, and that it is neither quiescent nor moveable. His celebrated arguments against the possibility of motion, afford a very favourable specimen of his reasoning. There are four of them, and they all take their rise, as Kant and Hamilton (Lectures on Metaphysics) have shown, from the inability of the mind to conceive either the ultimate indivisibility, or the endless divisibility, of space and time, as extensive and as protensive quantities. The possibility of motion, however certain as an observed fact, is thus shown to be inconceivable. To have discovered this peculiarity of our mental constitution, and to have stated it with eminent clearness, belongs to Zeno the Eleatic, and to him alone. His four arguments against motion are, in substance, as follows (see Aristotle, Phys. vi. 9):

1. Motion is impossible, for whatever is moved must traverse the intervening space, between where the motion begins and where it ends. Now, as this space merely consists of a series of points, in each of which the body must successively remain, of course motion is impossible.

2. This argument is that which is known as the celebrated problem of Achilles and the tortoise. It shows that a slow thing can never be overtaken by a swift; that Achilles, starting at any assigned time after a tortoise, cannot by any possibility overtake it, for as the tortoise, by hypothesis, is constantly in motion, and as the space over which it travels is infinitely divisible, Achilles can never overtake the tortoise.

3. That an arrow flying is immoveable; in other words, that motion and rest are identical. For that which occupies a certain space for a certain time is at rest; now the moving arrow does so, hence it is at rest.

4. Motion leads to absurdity. For suppose two bodies, equal in every respect, moved in a given space, and in an opposite direction, with the same force applied to both, and suppose the starting point of the one body to be one extremity of the space, and the starting place of the other body to be the centre of such space, both bodies will reach their destination at the same time; that is, the whole of the time occupied by the body that traversed the whole space was just equal to its half, or to the time taken by the body that merely traversed its half. Hence the whole time is equal to its half, which is absurd.

Zeno (Ζένω), the founder of the sect of the Stoics, was born about 350 B.C., at Citium, in the island of Cyprus. Clinton assigns his birth to between 357 B.C. and 352 B.C., and his death to between 263 B.C. and 259 B.C., the year given to it by Diogenes Laërtius. This place having been originally peopled by a colony of Phoenicians, Zeno is sometimes called a Phoenician. His father was by profession a merchant, but discovering in the youth a strong propensity towards learning, he early devoted him to philosophy. In his mercantile capacity he had frequent occasion to visit Athens, where he purchased for his son several of the writings of the most eminent Socratic philosophers. These he read with great avidity; and when he was about thirty years of age, or twenty-two according to his disciple Perseus, he determined to take a voyage to a city which was so celebrated both as a mart of trade and of science. Upon his first arrival in Athens, going accidentally into the shop of a bookseller, he took up a volume of the commentaries of Xenophon, and after reading a few passages, was so much delighted with the work, and formed so high an idea of the author, that he asked the bookseller where he might meet with such men. Crates, the Cynic philosopher, happening at that instant to be passing, the bookseller pointed to him and said, "Follow that man." Zeno attended upon the instructions of Crates, and was so well pleased with his doctrine, that he became one of his disciples. But though he admired the general principles of the Cynic school, he could not easily reconcile himself to their peculiar manners. Besides, his inquisitive turn of mind would not allow him to adopt that indifference to every scientific inquiry which was one of the characteristic distinctions of the sect. He therefore attended upon other masters, who professed to instruct their disciples in the nature and causes of things. When Crates, displeased at his following other philosophers, attempted to drag him by force out of the school of Stilpo, Zeno said to him, "You may seize my body, but Stilpo has laid hold of my mind."

After continuing to attend upon the lectures of Stilpo several years, he resorted to other schools, particularly to those of Xenocrates and Diodorus Cronus. By the latter he was instructed in dialectics. He was so much delighted with this branch of study, that he presented to his master a large pecuniary gratuity, in return for the free communication of some of his ingenious subtleties. At last, after attending almost every other master, he offered himself as a disciple of Polemo. This philosopher appears to have been aware that Zeno's intention, in thus removing from one school to another, was to collect materials from various quarters for a new system of his own; for, when he came into Polemo's school, he said to him, "I am no stranger, Zeno, to your Phoenician arts; I perceive that your design is to creep slyly into my garden and steal away my fruit." Polemo was not mistaken in his opinion. Having made himself master of the tenets of others, Zeno determined to become the founder of a new sect. The place which he made choice of for his school was a public portico, adorned with the pictures of Polygnotus and other eminent painters. It was the most famous portico in Athens, and called, by way of eminence, Ξενος, "the Porch." It was from this circumstance that the followers of Zeno were called Stoics.

In his person Zeno was tall and slender; his aspect was severe, and his brow contracted. He had not a very original mind, and he was even more eclectic in his philosophy than critical. His constitution was feeble, but he preserved his health by great abstinence. The supplies of his table consisted of figs, bread, and honey; notwithstanding which he was frequently honoured with the company of great men. In public company, to avoid every appearance of an assuming temper, he commonly took the lowest place. Indeed, so great was his modesty, that he seldom chose to mingle with a crowd, or wished for the company of more than two or three friends at once. He paid more attention to neatness and decorum in external appearance than the Cynic philosophers. In his dress, indeed, he was plain, and in all his expenses frugal; but this is not to be imputed to avarice, but a contempt of external magnificence. Zeno lived to the extreme age of ninety-eight; and at last, in consequence of an accident, voluntarily put an end to his life. As he was walking out of his school he fell down, and in the fall broke one of his fingers; upon which he was so affected with a consciousness of infirmity, that, striking the earth, he said, "Why am I thus importuned? I obey thy summons;" and immediately went home and strangled himself. The Athenians, at the request of Antigonus, erected a monument to his memory in the Ceramicum. For a full view of the Stoical system of which Zeno was the founder, see the Second Preliminary Dissertation prefixed to the present work.