Plato's great work of the middle period, the Republic , is devoted to answering a challenge made by the 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. (This general line of argument reoccurs much later in the philosophy of Nietzsche .) Throughout the rest of the Republic , Plato aims to refute this claim by showing that the virtue of justice is necessary for eudaimonia.
There is a humor in a young boy, who, about one-hundred years ago, loudly complained that a restaurant's employee served breakfast prior to the hours stated within the menu. Many people believe that the young boy grew up to become the world's smartest man. There exists a difference between the average mind and the prodigious mind, with the average mind choosing to accept inaccurate words as having accurate meanings, as well as accurate words having inaccurate meanings, but then too, the prodigious mind may be so strict that it might not catch the intended meaning at all.