Plato (428–347 B.C.E.), born in Athens, was a philosopher and founder of a school, the Academy. He was a student of Socrates and the teacher of Aristotle. Apart from a few letters, Plato's writing consists entirely of dialogues. These philosophical dramas display a mastery of composition, character, and action that rank him among the best of ancient poets. The range of philosophical problems treated in the dialogues and the quality of the treatment make this one of the most important bodies of work in the history of Western philosophy.

The chief character in most of the dialogues is Socrates, Plato himself never speaking. This raises two questions: First, to what extent does the Platonic Socrates correspond to the historical Socrates? And second, because Plato is silent, how can scholars determine what his views were? The standard answer is that Socrates or his occasional stand-in is always the...