XENOCRATES, OF CHALCEDON (396-314 B.c.), Greek philosopher and rector of the Academy from 339 to 314 B.c., removed to Athens in early youth. He became the pupil of the Socratic Aeschines, but presently joined himself to Plato, whom he attended to Sicily in 361. Upon his master's death (347 B.C.), in company with Aristotle he paid a visit to Hermias at Atarneus. In 339, Aristotle being then in Macedonia, Xenocrates succeeded Speusippus in the presidency of the school. On three occasions he was member of an Athenian legation, once to Philip, twice to Antipater. Soon after the death of Demosthenes in 322, resenting the Macedonian influence then dominant at Athens, Xenocrates declined the citizenship offered to him at the instance of Phocion, and, being unable to pay the tax levied upon resident aliens, was sold, or on the point of being sold, into slavery. He died in 314, and was succeeded by Polemon, whom he had reclaimed from a life of profligacy. Besides Polemon, the statesman Phocion, Chaeron, tyrant of Pellene, the Academic Crantor, the Stoic Zeno and Epicurus are alleged to have frequented his lectures.
Xenocrates's earnestness and strength of character won for him universal respect. Wanting in quickness of apprehension and in native grace, he made up for these deficiencies by a conscien tious love of truth and an untiring industry. Less original than Speusippus, he adhered more closely to the letter of Platonic doctrine, and is accounted the typical representative of the Old Academy. With Plato Xenocrates postulated ideas or numbers to be the causes of nature's organic products, and derived these ideas or numbers from unity (which is active) and plurality (which is passive) ; but unlike Plato, he took for his principles arithmetical unity and plurality, and accordingly identified ideal numbers with arithmetical numbers. In thus reverting to the crudities of certain Pythagoreans, he laid himself open to the criticisms of Aristotle, who, in his Metaphysics, recognizing amongst contemporary Pla tonists three principal groups—(r) those who, like Plato, dis tinguished mathematical and ideal numbers ; (2) those who, like Xenocrates, identified them; and (3) those who, like Speusippus, postulated mathematical numbers only—has much to say against the Xenocratean interpretation of the theory, and in particular points out that, if the ideas are numbers made up of arithmetical units, they not only cease to be principles, but also become subject to arithmetical operations. Xenocrates's theory of inorganic nature was substantially identical with the theory of the elements propounded in the Timaeus, 53 C seq. Nevertheless, holding that every dimension has a principle of its own, he rejected the derivation of the elemental solids—pyramid, octahedron, ico sahedron and cube—from triangular surfaces, and in so far ap proximated to atomism. Moreover, to the tetrad of simple ele
ments—viz., fire, air, water, earth—he added ether. His cosmology was also drawn almost entirely from the Timaeus.
Soul is a self-moving number, derived from the two funda mental principles, unity and plurality whence it obtains its powers of rest and motion. It is incorporeal, and may exist apart from body. The irrational soul, as well as the rational soul, is immortal. The universe, the heavenly bodies, man, animals, and presumably plants, are each of them endowed with a soul. Xenocrates identifies the universe and the heavenly bodies with the greater gods, and re serves a place between them and mortals for the lesser divinities. Xenocrates appears to have recognized three grades of cognition, each appropriated to a region of its own—viz., knowledge, opinion and sensation, having for their respective objects supra-celestials or ideas, celestials or stars, and infra-celestials or things. Of his logic we know only that with Plato he distinguished TO Ka0' can-6 and To rpds TL, rejecting the Aristotelian list of ten categories as a superfluity.
Valuing philosophy chiefly for its influence upon conduct, Xenocrates bestowed especial attention upon ethics. He wrote much upon this subject; but the indications of doctrine which have survived are scanty. Things are goods, ills or neutrals. Goods are of three sorts—mental, bodily, external; but of all goods virtue is incomparably the greatest. Happiness consists in the possession of virtue, and consequently is independent of personal and extraneous advantages. The virtuous man is pure, not in act only, but also in heart. To the attainment of virtue the best help is philosophy; for the philosopher does of his own accord what others do under the compulsion of law. Speculative wisdom and practical wisdom are to be distinguished.
Xenocrates was not in any sense a great thinker. His meta physic was a travesty rather than a reproduction of that of his master. His ethic had little which was distinctive. But his austere life and commanding personality made him an effective teacher, and his influence, kept alive by his pupils Polemon and Crates, ceased only when Arcesilaus, the founder of the so-called Second Academy, gave a new direction to the studies of the school.