Plato's Life
Plato was born in 427 (or 428) BCE, at a time when Athens was exiting the Golden Age (in part) due to the stresses of the Peloponnesian War. By 422, peace seemed to be on the horizon with the formal Peace of Nicias, but renewed warfare culminated in the Athenian defeat at Sicily (415, an engagement that was, you will remember, Alcibiades' idea!). The powerful Athenian navy was defeated by the Spartans and eventually the invaders would take Athens in 404. Thus, most of Plato's early life was lived under the shadow of Athenian defeat and desperation.
(As an aside, note that Plato was born just prior to the first productions of both Aristophanes' The Clouds, 423, and Sophocles' Oedipus Tyrannus, 425, two plays that have a definite theme of life during wartime).
As a young man, Plato spent time with the young aristocrats that were associated with Socrates. His uncle Charmides and his mother's cousin, Critias, were already among Socrates' friends (both of these individuals would be associated with the Thirty Tyrants). For Plato, Socrates represented a questing philosopher who would follow an investigation no matter where it would lead, and his virtues of courage, honesty, integrity, and devotion to the truth were valued by the young man. However, as we saw in our readings for the past few weeks, other Athenians did not agree with Plato's judgment, and Socrates' association with Alcibiades & the Thirty Tyrants, along with his constant questioning, proved his downfall. Plato was twenty-eight when Socrates drank the hemlock.
After Socrates' death, Plato left Athens for Megara and then traveled around the Mediterranean. He eventually returned to Athens and founded the Academy which has been described as the European worlds first intellectual organization (it was not really a site of education, more of an institute for advanced study, and often served as a political consultancy). The Academy would lead to the foundation of Aristotle's Lyceum, and later the Stoics would found schools in Athens, a city which would remain a center for philosophical activity until the 6th century CE.
Plato died in 348 or 347 BCE.
Plato's Works
Plato's works can be conveniently divided into four "periods".
The Socratic Period
These dialogs are "classic Socratic dialogues" in that they are clearly influenced by Socrates and may, in fact, represent the historical individual. Many of these works are, characteristically, without a definite result (remember Euthyphro?), and they clearly concentrate on moral theory (rather than metaphysics).
Transition Period - perhaps dating after 395 BCE.
Middle, or Mature, Period - probably dating before 367 BCE.
By now, Plato has largely left the questioning of ignorant Athenians and, rather than reducing the opponents to complete confusion, he has Socrates build complex theories in a manner that appears to be by questioning but is in fact a rhetorical device.
The Works of Old Age - the last twenty years of Plato's life