ecame a constant
attendant of Socrates, and lived at Athens till his death. After this
event, in consequence of the unpopularity of the very name of his master,
he retired to Megara, and subsequently to Sicily. He is said also to have
been at some part of his life, after the death of Socrates, a great
traveller. About twelve years after the death of Socrates he returned to
Athens, and began to teach in the Academy, partly by dialogue, and partly,
probably, by connected lectures. He taught gratuitously; and besides
Speusippus, Xenocrates, Aristotle, Heraclides Ponticus, and others, who
were devoted solely to philosophical studies, he is said to have
occasionally numbered Chabrias, Iphicrates, Timotheus, Phocion, Isocrates,
and (by some) Demosthenes among his hearers. He died at a great age, B.C.
347.

His works have come down to us in a more complete form than those of any
other ancient author who was equally voluminous; and from them we get a
clear idea of the principal doctrines which he inculcated on his
followers.

Like Socrates, he was penetrated with the idea, that knowledge and wisdom
were the things most necessary to man, and the greatest goods assigned to
him by God. Wisdom he looked on as the great purifier of the soul; and as
any approach to wisdom presupposes an original communion with _Being_,
properly so called, this communion also presupposes the divine nature, and
consequent immortality of the soul, his doctrine respecting which was of a
much purer and loftier character than the usual theology of the ancients.
Believing that the world also had a soul, he considered the human soul as
similar to it in nature, and free from all liability to death, in spite of
its being bound up with the appetites, in consequence of its connexion
with the body, and as preserving power and consciousness after its
separation from the body. What he believed, however, to be its condition
after death is far less certain, as his ideas on this subject are
expressed in a mythical form.

The chief point, however, to which Plato directed his attention, was
ethics, which, especially in his system, are closely connected with
politics. He devotes the Protagoras, and several shorter dialogues, to
refute the sensual and selfish theories of some of his predecessors, in
order to adopt a more scientific treatment of the subject; and in these
dialogues he urges that neither happiness nor virtue are attainable by the
indulgence of our desires