This interpretive introduction provides unique insight into Plato's Republic. Stressing Plato's desire to stimulate philosophical thinking in his readers, Julia Annas here demonstrates the coherence of his main moral argument on the nature of justice, and expounds related concepts of education, human motivation, knowledge and understanding. In a clear systematic fashion, this book shows that modern moral philosophy still has much to learn from Plato's attempt to move the focus from questions of what acts the just person ought to perform to the more profound questions of what sort of person the just person ought to be.