XENOCIULTES, an ancient philosopher, was b. at Chalcedon 396 B.c., and died 314. At an early age, he attached himself to Plato, and in course of time, was so much esteemed for his proficiency in philosophy and high moral character, that he was thought worthy of succeeding Speusippus, Plato's successor, in the presidency of the academy. This post he filled most creditably for 25 years. He wrote numerous treatises upon dialectics, physics, and ethics, and drew with unusual precision the boundaries between these three departments of philosophy. Of these works merely the titles have been preserved; and what is known of his doctrines is gathered only from notices of them contained in various authors. He introduced into the academy, to a greater degree than before, the mystic Pythagorean doctrine of numbers, in connection with the ideas of Plato. Zeus, the father, ruling in heaven, he called Unity, as being uneven number and spirit; the world-soul, which operates through all things liable to motion and change, he styled Duality. This divine world-soul dwells in the heavenly
bodies, the Olympic gods, the elements of nature, and also in terrestrial demons, whom he regarded as intermediate between gods and men. In his ethical teaching, he aimed at making the Platonic doctrines more directly applicable to ordinary life in individual cases, and pitched his standard of excellence very high. He held that virtue is in itself valuable, while other things are only so conditionally, and that it extended to thoughts as well as actions. He was himself of irreproachable character, of a well-balanced mind, and temperate in his habits without cynicism. His conversion 'of the youthful debauchee Polemo into an earnest, virtuous man, and his disregard for wealth, as shown by his refusal of the offers of Philip and Alexander, are the best-known incidents in his long, useful, and virtuous career.