 Ancient ethics was, in a sense, more concerned with well-being than a good deal of modern ethics, the central question for many ancient moral philosophers being, ‘Which life is best for one?’. The rationality of egoism—the view that my strongest reason is always to advance my own well-being—was largely assumed. This posed a problem. Morality is naturally thought to concern the interests of others. So if egoism is correct, what reason do I have to be moral?