Plato is outstanding among philosophers, more or less inventing philosophy as we know it in the West. In the Republic he begins with the question 'What is justice?', but this question soon broadens into an investigation of what is real and how we can know it, so defining the three main areas of philosophy -ethics, metaphysics and epistemology (the theory of the method or grounds of knowledge). But Plato is remarkable also for the beauty of his writing. The allegory of the cave at the beginning of Republic Book 7 is among the most powerful images in the history of literature. And in the Protagoras and Gorgias his portraits of the intellectual elite of the Greek world in the 5th century BCE are without parallel.