Plato, a student of Socrates and teacher of Aristotle, was the founder of the Academy in Athens, the first institution of higher learning in the Western world. His philosophical work is mostly written in the form of 'Dialogues,' with Socrates as the main character. His most famous work, 'The Republic,' explores the nature of justice and the ideal city-state ruled by 'philosopher-kings.' Plato introduced the Theory of Forms, suggesting that the physical world we perceive is only a shadow of a higher, eternal reality. His 'Allegory of the Cave' remains one of the most famous metaphors in philosophy, illustrating the effects of education on the human soul and the difficulty of perceiving true reality. His thoughts on ethics, politics, and metaphysics have formed the backbone of Western intellectual tradition.