A Socratic dialogue led by Socrates interrogates the nature of justice, contrasting conventional views with Thrasymachus's claim that justice serves the powerful and answering Glaucon's challenge about its intrinsic value. To define justice the interlocutors construct an ideal city, outlining social classes, the education and censorship suited to guardians, and the specialization of roles. The conversation develops into a wider account of the soul's tripartite structure and its harmony as justice, argues for rule by philosophically trained leaders, presents metaphors for knowledge such as the allegory of the cave and the theory of forms, and traces how political regimes decline through successive stages.