Plato (c. 428/427 or 424/423 – 348/347 BC) was an Athenian philosopher who, along with his mentor Socrates and his student Aristotle, laid the foundations of Western and Greek philosophy. His best-known work is the Theory of Forms, according to which the sensible world is an imperfect copy of an intelligible world, of Forms or Ideas. Plato wrote numerous philosophical dialogues, in which Socrates is usually the main interlocutor. He founded the Academy in Athens, the first institution of higher learning in the Western world. His ideas profoundly influenced philosophy, theology, science, and politics. He is considered one of the greatest thinkers of all time.