How did philosophers like Socrates and Pythagoras influence Plato? What is his puzzling theory of knowledge all about, and how did it direct his provocative views on politics, ethics, individual liberty and many other subjects? Introducing Plato explains all of Plato's key ideas, especially the very odd 'theory of Forms', and concludes by revealing how Plato has stimulated the work of modern thinkers such as Karl Popper and Jacques Derrida.