Nicomachean Ethics

Now men suppose that acting Unjustly rests entirely with themselves, and conclude that acting Justly is therefore also easy. But this is not really so; to have connection with a neighbour’s wife, or strike one’s neighbour, or give the money with one’s hand, is of course easy and rests with one’s self: but the doing these acts with certain inward dispositions neither is easy nor rests entirely with one’s self. And in like way, the knowing what is Just and what Unjust men think no great instance of wisdom because it is not hard to comprehend those things of which the laws speak. They forget that these are not Just actions, except accidentally: to be Just they must be done and distributed in a certain manner: and this is a more difficult task than knowing what things are wholesome; for in this branch of knowledge it is an easy matter to know honey, wine, hellebore, cautery, or the use of the knife, but the knowing how one should administer these with a view to health, and to whom and at what time, amounts in fact to being a physician.

From this very same mistake they suppose also, that acting Unjustly is equally in the power of the Just man, for the Just man no less, nay even more, than the Unjust, may be able to do the particular acts; he may be able to have intercourse with a woman or strike a man; or the brave man to throw away his shield and turn his back and run this way or that. True: but then it is not the mere doing these things which constitutes acts of cowardice or injustice (except accidentally), but the doing them with certain inward dispositions: just as it is not the mere using or not using the knife, administering or not administering certain drugs, which constitutes medical treatment or curing, but doing these things in a certain particular way.

Again the abstract principles of Justice have their province among those who partake of what is abstractedly good, and can have too much or too little of these.[28] Now there are beings who cannot have too much of them, as perhaps the gods; there are others, again, to whom no particle of them is of use, those who are incurably wicked to whom all things are hurtful; others to whom they are useful to a certain degree: for this reason then the province of Justice is among .