Xenocrates was a native of Chalcedon, born probably b.c. 396. He was a follower of Plato, and accompanied him to Sicily. After his death, he betook himself, with Aristotle, to the court of Hermias, tyrant of Ptarneus, but soon returned to Athens, and became president of the Academy when Speusippus, through ill health, was forced to abandon that post. He died b.c. 314.
He was not a man of great genius, but of unwearied industry and the purest virtue and integrity. None of his works have come down to us; but, from the notices of other writers, we are acquainted with some of his peculiar doctrines. [pg xxiv] He stood at the head of those who, regarding the universe as imperishable and existing from eternity, looked upon the chronic succession in the theory of Plato as a form in which to denote the relations of conceptual succession. He asserted that the soul was a self-moving member,—called Unity and Duality deities, considering the former as the first male existence, ruling in heaven, father and Jupiter; the latter as the female, as the mother of the Gods, and the soul of the universe, which reigns over the mutable world under heaven. He approximated to the Pythagoreans in considering Number as the principle of consciousness, and consequently of knowledge; supplying, however, what was deficient in the Pythagorean theory by the definition of Plato, that it is only in as far as number reconciles the opposition between the same and the different, and can raise itself to independent motion, that it is soul.
In his ethics he endeavoured to render the Platonic theory more complete, and to give it a more direct applicability to human life; admitting, besides the good and the bad, of something which is neither good nor bad, and some of these intermediate things, such as health, beauty, fame, good fortune, he would not admit to be absolutely worthless and indifferent. He maintained, however, in the most decided manner, that virtue is the only thing valuable in itself, and that the value of everything else is conditional, (see Cic. de Fin. iv. 18, de Leg. i. 21, Acad. i. 6, Tusc. Quæst. v. 10-18,) that happiness ought to coincide with the consciousness of virtue. He did not allow that mere intellectual scientific wisdom was the only true wisdom to be sought after as such by men: and in one point he came nearer the precepts of Christianity than any of the ancients, when he asserted the indispensableness of the morality of the thoughts to virtue, and declared it to be the same thing, whether a person cast longing eyes on the possessions of his neighbour, or attempted to possess himself of them by force.
Antisthenes was older than Plato; though the exact time of his birth is uncertain: but he fought at the battle of Tanagra, b.c. 420, though then very young. He became a [pg xxv] disciple of Gorgias, and afterwards of Socrates, at whose death he set up a school in the Cynosarges, a gymnasium for the use of Athenians born of foreign mothers, near the temple of Hercules, from which place of assembly his followers were called Cynics. He lived to a great age, though the year of his death is not known, but he certainly was alive after the battle of Leuctra, b.c. 371.
In his philosophical system, which was almost confined to ethics, he appears to have aimed at novelty rather than truth or common sense. He taught that in all that the wise man does he conforms to perfect virtue, and that pleasure is so far from being necessary to man, that it is a positive evil. He is reported also to have gone the length of pronouncing pain and infamy blessings rather than evils, though when he spoke of pleasure as worthless, he probably meant that pleasure which arises from the gratification of sensual or artificial desires; for he praised that which arises from the intellect, and from friendship. The summum bonum he placed in a life according to virtue.
In a treatise in which he discussed the nature of the Gods he contended for the unity of the Deity, and asserted that man is unable to know him by any sensible representation, since he is unlike any being on earth; and demonstrated the sufficiency of virtue for happiness, by the doctrine that outward events are regulated by God so as to benefit the wise and good.
Diogenes, a native of Sinope in Pontus, who was born b.c. 412, was one of his few disciples; he came at an early age to Athens, and became notorious for the most frantic excesses of moroseness and self-denial. On a voyage to Ægina he was taken by pirates and sold as a slave to Xeniades, a Corinthian, over whom he acquired great influence, and was made tutor to his children. His system consisted merely in teaching men to dispense with even the simplest necessaries of civilized life: and he is said to have taught that all minds are air, exactly alike, and composed of similar particles; but that in beasts and in idiots they are hindered from properly developing themselves by various humors and incapacities [pg xxvi] of their bodies. He died b.c. 323, the same year that Epicurus came to Athens.
Zeno was born at Citium, a city of Cyprus; but having been shipwrecked near Cyprus, he settled in that city, where he devoted himself to severe study for a great length of time, cultivating, it is said, the acquaintance of the philosophers of the Megaric school, Diodorus and Philo, and of the Academics, Xenocrates and Polemo. After he had completed his studies, he opened a school himself in the porch, adorned with the paintings of Polygnotus (Στοὰ ποικίλη), from which his followers were called Stoics. The times of his birth and of his death are not known with any exactness; but he is said to have reached a great age.
In speaking of the Stoic doctrines, it is not very clear how much of them proceeded from Zeno himself, and how much from Chrysippus and other eminent men of the school in subsequent years. In natural philosophy he considered that there was a primary matter which was never increased or diminished, and which was the foundation of everything which existed: and which was brought into existence by the operative power,—that is, by the Deity. He saw this operative power in fire and in æther as the basis of all vital activity, (see Cic. Acad. i. 11, ii. 41; de Nat. Deor. ii. 9, iii. 14,) and he taught that the universe comes into being when the primary substance passing from fire through the intermediate stage of air becomes liquefied, and then the thick portion becomes earth, the thinner portion air, which is again rarefied till it becomes fire. This fire he conceived to be identical with the Deity, (Cic. de Nat. Deor. ii. 22,) and to be endowed with consciousness and foresight. At other times he defined the Deity as that law of nature which ever accomplishes what is right, and prevents the opposite, and identified it with unconditional necessity. The soul of man he considered as being of the nature of fire, or of a warm breath, (Cic. Tusc. Quæst. i. 9; de Nat. Deor. iii. 4,) and therefore as mortal.
In ethics he agreed with the Cynics in recognising the constitutional nature of moral obligations, though he differed from them with respect to things indifferent, and opposed their [pg xxvii] morose contempt for custom, though he did not allow that the gratification of mere external wants, or that external good fortune, had any intrinsic value. He comprised everything which could make life happy in virtue alone (Cic. Acad. i. 10), and called it the only good which deserved to be striven after and praised for its own sake (Cic. de Fin. iii. 6, 8), and taught that the attainment of it must inevitably produce happiness. But as virtue could, according to his system, only subsist in conjunction with the perfect dominion of reason, and vice only in the renunciation of the authority of reason, he inferred that one good action could not be more virtuous than another, and that a person who had one virtue had all, and that he who was destitute of one was destitute of all.