Greek philosopher who lived from 427? to 347 B.C. In 407 B.C. he became a
pupil and friend of Socrates. After living for a Time at the Syracuse court, Plato founded (c.387 B.C.) near Athens the most
influential school of the ancient world, the Academy, where he taught until his
death. His most famous pupil there was Aristotle. Plato's extant work is in the form of epistles and dialogues, divided
according to the probable order of composition. The early, or Socratic, dialogues,
e.g., the Apology, Meno, and Gorgias, present Socrates in conversations that
illustrate his major ideas-the unity of virtue and knowledge and of virtue and
happiness. They also contain Plato's moving account of the last days and death of
Socrates. Plato's goal in dialogues of the middle years, e.g., the Republic,
Phaedo, Symposium, and Timaeus, was to show the rational relationship between the
soul, the state, and the cosmos. The later dialogues, e.g., the Laws and
Parmenides, contain treatises on law, mathematics, technical philosophic problems,
and natural science. Plato regarded the rational soul as immortal, and he
believed in a world soul and a Demiurge, the creator of the physical world. He argued
for the independent reality of Ideas, or Forms, as the immutable archetypes of
all temporal phenomena and as the only guarantee of ethical standards and of
objective scientific knowledge. Virtue consists in the harmony of the human soul
with the universe of Ideas, which assure order, intelligence, and pattern to a
world in constant flux. Supreme among them is the Idea of the Good, analogous
to the Sun in the physical world. Only the philosopher, who understands the harmony of
all parts of the universe with the Idea of the Good, is capable of ruling the
just state. In Plato's various dialogues he touched upon virtually every problem
that has occupied subsequent philosophers; his teachings have been among the
most influential in the history of Western civilization, and his works are
counted among the world's finest literature.