The Athens-born Plato (originally, Aristocles) was Socrates’s disciple and Aristotle’s teacher. The philosophies of these three men combined to lay the foundations of Western thought.

With the death sentence of his spiritual guide, Socrates, in 399 B.C., Plato’s (c. 428–347 B.C.) dissatisfaction with the Athenian government reached its peak. Traveling throughout the Mediterranean after the death of Socrates, Plato returned to Athens in 387 B.C., and one mile outside of the city he established the Academy, a school of philosophy supported entirely by philanthropists; students paid no fees. One of the pupils there was young Aristotle (384–322 B.C.), who remained at the Academy for 20 years before venturing out on his own.

Plato wrote a series of dialogues in which Socrates figures prominently. The most highly regarded of these is the Republic, in which Plato discusses justice and the ideal state. It was his belief that people would not be able to eliminate injustice from society until rulers became philosophers: “Until all philosophers are kings, or the kings and princes of this world have the spirit and power of philosophy, and political greatness and wisdom meet in one, and those commoner natures who pursue either to the exclusion of the other are compelled to stand aside, cities will never have rest from their evils—no, nor the human race.” Also on the subject of the ideal state, Plato wrote but did not finish Laws. His other works include Symposium, which considers ideal love; Phaedrus, which attacks the prevailing notions about rhetoric; Apology, which is a rendering of the speech Socrates delivered at his own trial in 399 B.C.; and Phaedo, which discusses the immortality of the soul and which is supposed to be a record of Socrates’s last conversation before he drank hemlock and died.