Plato (428/27 — 348/47 B.C.) was twenty-nine years old when his teacher Socrates died. In the course of his lengthy life Plato used dialogues, an inherently dramatic form, to pour forth a complete system of philosophy. Plato was a polymath at work. He was equally comfortable writing on ethics, epistemology, metaphysics, political philosophy, and aesthetics (philosophy of art). He made contributions to every branch of philosophy, leaving behind a system of thought that is breathtaking in breadth and depth.