Plato’s great work of the middle period, the Republic, is devoted to answering a challenge made by a sophist Thrasymachus, that conventional morality, particularly the ‘virtue’ of justice, actually prevents the strong man from achieving eudaimonia. Thrasymachus’s views are restatements of a position which Plato discusses earlier on in his writings, in the Gorgias, through the mouthpiece of Callicles. The basic argument presented by Thrasymachus and Callicles is that justice (being just) hinders or prevents the achievement of eudaimonia because conventional morality requires that we control ourselves and hence live with un-satiated desires. This idea is vividly illustrated in book 2 of the Republic when Glaucon, taking up Thrasymachus’ challenge, recounts a myth of the magical ring of Gyges. According to the myth, Gyges becomes king of Lydia when he stumbles upon a magical ring, which, when he turns it a particular way, makes him invisible, so that he can satisfy any desire he wishes without fear of punishment. When he discovers the power of the ring he kills the king, marries his wife and takes over the throne. The thrust of Glaucon’s challenge is that no one would be just if he could escape the retribution he would normally encounter for fulfilling his desires at whim. But if eudaimonia is to be achieved through the satisfaction of desire, whereas being just or acting justly requires suppression of desire, then it is not in the interests of the strong man to act according to the dictates of conventional morality.