PYTHAGORAS TO PLATO and ethics These ramiWcations of the theory will be considered in later chapters But the Republic is best known to the world at large not for its manifold exploitation of the theory, but for the political arrangements that are described in its central books The oYcial topic of the dialogue is the nature and value of justice After several candidate deWnitions for justice have been examined and found wanting in the Wrst book (which probably originally existed as a separate dialogue), the main part of the work begins with a challenge to Socrates to prove that justice is something worthwhile for its own sake Plato’s brothers Glaucon and Adeimantus, who are characters in the dialogue, argue that justice is chosen as a way of avoiding evil To avoid being oppressed by others, Glaucon says, weak human beings make compacts with each other neither to suVer nor to commit injustice People would much prefer to act unjustly if they could so with impunity—the kind of impunity a man would have, for instance, if he could make himself invisible so that his misdeeds passed undetected Adeimantus supports his brother, saying that among humans the rewards of justice are the rewards of seeming to be just rather than the rewards of actually being just, and with regard to the gods the penalties of injustice can be bought oV by prayer and sacriWce (2 358a–367e) We shall see in Chapter how Socrates responds, through the remaining books of the dialogue, to this initial challenge Now, in the interests of setting out Plato’s political philosophy, we should concentrate on his immediate response To answer the brothers he shifts from the consideration of justice, or righteousness, in the individual person to the larger issue of justice in the city-state There, he says, the nature of justice will be written in bigger letters and therefore easier to read The purpose of living in cities is to enable people with diVerent skills to supply each other’s needs by an appropriate division of labour Ideally, if people were content as they once were with the satisfaction of their basic needs, a very simple community would suYce But in the modern luxurious age citizens demand more than mere subsistence, and this necessitates more complicated political arrangements, including a well-trained professional army (2 369b–374d) Socrates now presents a blueprint for a city with three classes Those among the soldiers best Wtted to rule are selected by competition to form the upper class, called guardians; the remaining soldiers are described as auxiliaries, and the rest of the citizens belong to the class of farmers and 57