Greek philosopher, mathematician, and teacher. Born to an aristocratic family, probably in Athens, Plato was among the most ardent students of the philosopher Socrates. After Socrates was executed in 399 b.c.e., Plato is believed to have traveled throughout the Mediterranean before returning in the 380s to found the Academy, the Western world's first formally constituted institution of higher learning. Most of Plato's known writings are dialogues featuring Socrates in vigorous pursuit of the truth of human existence through tireless questioning. The best known of these Socratic dialogues, the Republic, probes the nature of justice, the relationship between the individual and society, and the ideal "forms" that are, Plato believed, the ultimate reality beyond the world we experience with our senses. Plato remains enormously influential; his teachings were carried on by his student Aristotle, and indeed all of Western philosophy has been called "footnotes to Plato." See also plato.stanford.edu.