Nicomachean Ethics

pain that moves us to refrain from what is noble. And therefore, as Plato says, man needs to be so trained from his youth up as to find pleasure and pain in the right objects. This is what sound education means.
Another reason why virtue has to do with pleasure and pain, is that it has to do with actions and passions or affections; but every affection and every act is accompanied by pleasure or pain.
The fact is further attested by the employment of pleasure and pain in correction; they have a kind of curative property, and a cure is effected by administering the opposite of the disease.
Again, as we said before, every type of character [or habit or formed faculty] is essentially relative to, and concerned with, those things that form it for good or for ill; but it is through pleasure and pain that bad characters are formed⁠—that is to say, through pursuing and avoiding the wrong pleasures and pains, or pursuing and avoiding them at the wrong time, or in the wrong manner, or in any other of the various ways of going wrong that may be distinguished.
And hence some people go so far as to define the virtues as a kind of impassive or neutral state of mind. But they err in stating this absolutely, instead of qualifying it by the addition of the right and wrong manner, time,  etc.
We may lay down, therefore, that this kind of excellence [ i.e. moral excellence] makes us do what is best in matters of pleasure and pain, while vice or badness has the contrary effect. But the following considerations will throw additional light on the point. 23
There are three kinds of things that move us to choose, and three that move us to avoid them: on the one hand, the beautiful or noble, the advantageous, the pleasant; on the other hand, the ugly or base, the hurtful, the painful. Now, the good man is apt to go right, and the bad man to go wrong, about them all, but especially about pleasure: for pleasure is not only common to man with animals, but also accompanies all pursuit or choice; since the noble, and the advantageous also, are pleasant in idea.
Again, the feeling of pleasure has been fostered in us all from our infancy by our training, and has thus become so engrained in our life that it can scarce be washed out. 24 And, indeed, we all more or less make pleasure our test in judging of actions. For this reason too, then, our whole inquiry must be concerned with these matters; since to be pleased and pained in the right or the wrong way has great influence on our actions.
Again, to fight with pleasure is harder than to fight with wrath (which Heraclitus says is hard), and virtue, like art, is always more concerned with what is harder; for the harder the task the better is success. For this reason also, then, both [moral] virtue or excellence and the science of the state must always be concerned with pleasures and pains; for he that behaves rightly with regard to them will be good, and he that behaves badly will be bad.
We will take it as established, then, that [moral] excellence or virtue has to do with pleasures and pains; and that the acts which produce it develop it, and also, when differently done, destroy it; and that it manifests itself in the same acts which produced it.

IV
But here we may be asked what we mean by saying that men can become just and temperate only by doing what is just and temperate: surely, it may be said, if their acts are just and temperate, they themselves are already just and temperate, as they are grammarians and musicians if they do what is grammatical and musical.
We may answer, I think, firstly, that this is not quite the case even with the arts. A man may do something grammatical [or write something correctly] by chance, or at the prompting of another person: he will not be grammatical till he not only does something grammatical, but also does it grammatically [or like a grammatical person],  i.e. in virtue of his own knowledge of grammar.
But, secondly, the virtues are not in this point analogous to the arts. The products of art have their excellence in themselves, and so it is enough if when produced they are of a certain quality; but in the case of the virtues, a man is not said to act justly or temperately [or like a just or temperate man] if what he does merely be of a certain sort⁠—he must also be in a certain state of mind when he does it;  i.e., first of all, he must know what he is doing; secondly, he must choose it, and choose it for itself; and, thirdly, his act must be the expression of a formed and stable character. Now, of these conditions, only one, the knowledge, is necessary for the possession of any art; but for the possession of the virtues knowledge is of little or no avail, while the other conditions that result from repeatedly doing what is just and temperate are not a little important, but all-important.
The thing that is done, therefore, is called just or temperate when it is such as the just or temperate man would do; but the man who does it is not just or temperate, unless he also does it in the spirit of the just or the temperate man.
It is right, then, to say that by doing what is just a man becomes just, and temperate by doing what is temperate, while without doing thus he has no chance of ever becoming good.
But most men, instead of doing thus, fly to theories, and fancy that they are philosophizing and that this will make them good, like a sick man who listens attentively to what the doctor says and