Xenocrates a Greek philosopher, was born in Chalcedon, 396 B.C. He was originally a pupil of Eschines, the Socratic philosopher, and afterwards of Plato. His intimate connection with Plato is indicated by the account that he accompanied that master to Syracuse. After the death of Plato he betook himself, with Aristotle, to Hermias, tyrant of Atarneus and Assus, and, after his return to Athens, was repeatedly sent on embassies to Phlilip of Macedonia, and at a later time to Antipater, during the Lamian war. The want of quick apprehension and natural grace he compensated by persevering and thorough-going industry, pure benevolence, purity of morals, unselfishness, and a moral earnestness which compelled esteem and trust even from the Athenians of his own age. Yet even he experienced the fickleness of popular favor, and being too poor to pay the μετοίκιον, or protection money, is said to have been saved only by the courage of the orator Lycurgus, or even to have been bought by Demetrius Plialereus, and then emancipated. He became president of the academy, 339 B.C., even before the death of Spensippus, and occupied the post for twenty-five years. He died in 314 B.C. Xenocrates' doctrines were discussed by Aristotle and Theophrastus, and he was held in high regard by such men as Panaetius and Cicero. Diogenes Laertius gives a long list of his writings, but the works themselves have perished. With a more comprehensive work on dialectic there were connected separate treatises on science, on divisions, on genera and species, on ideas, on the opposite, and others, to which probably the work on mediate thought also belonged. Two works on physics are mentioned, as are also books upon the gods, on the existent, on the One, on the indefinite, on the soul, on the affections, on memory, etc. In like manner, with the more general ethical treatises on happiness and on virtue, there were connected separate books on individual virtues, on the voluntary, etc. His four books on royalty he had addressed to Alexander. Besides these, he had written treatises on the state, on the power of law, etc., as well as upon geometry, arithmetic, and astrology. We know little of the doctrines of Xenocrates, but we may infer that he exhibited his opinions in a systematic form, and not in dialogues, like his master, Plato. To him is attributed the division of philosophy into logic, ethic, and physic, or physics. He occupied himself principally with attempting to reduce the ideal doctrines of Plato to mathematical elements. He predicted three forms of being — the sensuous, that which is perceived by the intellect, and that which is compounded and consists in opinion. In his positions we see the tendency of the academy towards the Pythagorean doctrines of number. Unity and duality he considers as the gods which rule the world, and the soul as a self-moving number. Other like conceits are attributed to him. Xenocrates considered that the notion of the deity pervades all things, and is even in the animals which we call irrational. He also admitted an order of daemons or something intermediate between the divine and the mortal, which he made to consist in the conditions of the soul. In his ethical teaching he made happiness consist not in the possession of a virtuous mind only, but also of all the powers that minister to it and enable it to effect its purposes. How decidedly he insisted, not only on the recognition of the unconditional nature of moral excellence, but on morality of thought, is shown by the declaration that it comes to the same thing whether one casts longing eyes or sets his feet upon the property of others. His moral earnestness is also expressed in the warning that the ears of children should be guarded against the poison of immoral speeches. See Van de Wynpersee, Diatribe de Xenocrate Chalcedonio (1822); Diogenes Laertius, Xenocrates; Ritter, Geschichte der Philosophie, 2; Ueberweg, History of Philosophy, 1:133 sq.; Smith, Dict. of Greek and Rom. Biog. and Myth. s.v.