ETHICS of the way in which the virtues intertwine and form a unity Actions that exhibit courage are of course diVerent actions from those that exhibit temperance; but what they express is a single, indivisible state of soul If we say that courage is the science of what is good and bad in respect of future dangers, we have to agree that such a science is only possible as part of an overall science of good and evil (La 199c) The individual virtues are parts of this science, but it can only be possessed as a whole No one, not even Socrates, is in possession of this science.1 We are, however, given an account of what it would look like, and it is rather a surprising account Socrates asks Protagoras, in the dialogue named after him, to accept the premiss that goodness is identical with pleasure and evil is identical with pain From this premiss he oVers to prove his contention that no one does evil willingly People are often said to have done evil in the knowledge that it was evil because they yielded to temptation and were overcome by pleasure But if ‘pleasure’ and ‘good’ mean the same, then they must have done evil because they were overcome by goodness Is not that absurd (354c–5d)? Knowledge is a powerful thing, and the knowledge that something is evil cannot be pushed about like a slave Given the premiss that Protagoras has accepted, knowledge that an action is evil must be knowledge that, taken with its consequences, the action will lead to an excess of pain over pleasure No one with such knowledge is going to undertake such an action; hence the person acting wrongly must lack the knowledge Nearby objects seem larger to vision than distant ones, and something similar happens in mental vision The wrongdoer is suVering from the illusion that the present pleasure outweighs the consequent pain What is needed is a science that measures the relative sizes of pleasures and pains, present and future, ‘since our salvation in life has turned out to lie in the correct choice of pleasure and pain’ (356d–357b) This is the science of good and evil that is identical with each of the virtues, justice, temperance, and courage (361b) Here I am indebted to a number of articles by Terry Penner, summed up in his essay ‘Socrates and the Early Dialogues’, in R Kraut (ed.), The Cambridge Companion to Plato (Cambridge: Cambridge University Press, 1992) 263