 It all begins with the challenge to the very notion of morality, understood along traditional lines, mounted by Callicles in the second half of the Gorgias and by Thrasymachus in Republic I. Callicles thinks that moral convention is designed by the numerous weak people to intimidate the few strong ones, to keep the latter from taking what they could if they would only use their strength. No truly strong person should be taken in by such conventions (Gorg. 482e ff). Thrasymachus argues that justice is the advantage of the more powerful; he holds that justice is a social practice set up by the powerful, i.e., rulers who require their subjects through that practice to act against their own individual and group self-interest (Rep. 338d ff). No sensible person should, and no strong-willed person would, accept rules of justice as having any legitimate authority over them. In answer to the latter challenge, in Republic II, Glaucon and Adeimantus repeatedly urge Socrates to show what value justice has in itself, apart from its rewards and reputation. They gloss the intrinsic value of justice as what value it has in the soul (358b–c), what it does to the soul simply and immediately by its presence therein. Before giving what will be a new account of the soul, Socrates introduces his famous comparison between the soul and the city. As he develops his account of the city, however, it becomes clear that Socrates is talking about an ideal city, which he proceeds to construct in his discussion.