（Ξενοκράτης). A philosopher, born at Chalcedon in B.C. 400. He first attached himself to Æschines, but afterwards became a disciple of Plato, who took much pains in cultivating his genius, which was naturally heavy. Plato, comparing him with Aristotle, who was also one of his pupils, called the former a dull ass who needed the spur, and the latter a mettlesome horse who required the curb. His temper was gloomy, his aspect stern, and his manners little tinctured with urbanity. These material defects his master took great pains to correct, frequently advising him to sacrifice to the Graces; and the pupil, patient of instruction, knew how to value the kindness of his preceptor. He compared himself to a vessel with a narrow orifice, which receives with difficulty, but firmly retains whatever is put into it. So attached was Xenocrates to his master that when Dionysius, in a violent fit of anger, threatened to find one who should cut off his head, he said, “Not before he has cut off this,” pointing to his own. As long as Plato lived, Xenocrates was one of his most esteemed disciples; after his death he closely adhered to his doctrine; and in B.C. 339 he took the chair in the Academy as the successor of Speusippus. Aristotle, who, about this time, returned from Macedonia, in expectation, as it should seem, of filling the chair, was greatly disappointed and chagrined at this nomination, and immediately instituted a school in the Lyceum, in opposition to that of the Academy where Xenocrates continued to preside till his death. Xenocrates was celebrated among the Athenians, not only for his wisdom, but also for his virtues (Val. Max. ii. 10; ii. 16; Diog. Laert. iv. 7).

So eminent was his reputation for integrity that when he was called upon to give evidence in a judicial transaction, in which an oath was usually required, the judges unanimously agreed that his simple asseveration should be taken, as a public testimony to his merit. Even Philip of Macedon found it impossible to corrupt him. When he was sent, with several others, upon an embassy to that king, he declined all private intercourse with him, that he might escape the temptations of a bribe. Philip afterwards said that of all those who had come to him on embassies from foreign States, Xenocrates was the only one whose friendship he had not been able to purchase (Diog. Laert. iv. 8). During the time of the Lamiac War, being sent an ambassador to the court of Antipater for the redemption of several Athenian captives, he was invited by the prince to sit down with him at supper, but declined the invitation in the words of Odysseus to Circé ( x. 383). This pertinent and ingenious application of a passage in Homer, or, rather, the generous and patriotic spirit which it expressed, was so pleasing to Antipater that he immediately released the prisoners. It may be mentioned as another example of moderation in Xenocrates, that when Alexander, to mortify Aristotle, against whom he had an accidental pique, sent Xenocrates a magnificent present of fifty talents, he accepted only thirty minae, returning the rest to Alexander with this message: that the large sum which Alexander had sent was more than he should have been able to spend during his whole life. So abstemious was he with respect to food that his provision was frequently spoiled before it was consumed. His chastity was invincible, and Laïs, a celebrated Athenian courtesan, attempted, without success, to seduce him. He was an admirer of the mathematical sciences, and was so fully convinced of their utility that when a young man who was unacquainted with geometry and astronomy desired admission, he refused his request, saying that he was not yet possessed of the handles of philosophy. In fine, Xenocrates was eminent both for the purity of his morals and for his acquaintance with science, and supported the credit of the Platonic School by his lectures, his writings, and his conduct. He lived until B.C. 316, when he lost his life by accidentally falling, in the dark, into a reservoir of water.

The philosophical tenets of Xenocrates were truly Platonic, but in his method of teaching he made use of the language of the Pythagoreans. He made Unity and Diversity principles in nature, or gods; the former of whom he represented as the father, and the latter as the mother, of the universe. He taught that the heavens are divine, and the stars gods; and that, besides these divinities, there are terrestrial demons of a middle order, between the gods and man, which partake of the nature both of mind and body, and are therefore, like human beings, capable of passions and liable to diversity of character.