Book One presents a discussion of the nature of justice by Socrates, the aging Cephalus, his son Polemarchus, and the sophist Thrasymachus. Plato's brothers, Glaucon and Adeimantus, take over in Book Two, challenging Socrates to convince them that a just life is preferable to an unjust life with power, fame, and riches. They imagine and evaluate different ways of creating the best possible human life. First they consider a republic based on health and simplicity. When Glaucon dismisses that kind of life as fit only for pigs, they construct a republic based on wealth and luxury. Their analysis of economic and political reality introduces the division of labor, the origin of war, a common currency, and basic principles for educating the young. The goal of this quest is to reveal the foundations of justice and injustice and evaluate their merits.