Book 3: The Will.
Chapter 4: We wish for
Wish, we have already said, is for the end; but whereas some hold that the object of wish is the good others hold that it is what seems good.
Those who maintain that the object of wish is the good have to admit that what those wish for who choose wrongly is not object of wish (for if so it would be good; but it may so happen that it was bad); on the other hand, those who maintain that the object of wish is what seems good have to admit that there is nothing which is naturally object of wish, but that each wishes for what seems good to him—different and even contrary things seeming good to different people.
As neither of these alternatives quite satisfies us, perhaps we had better say that the good is the real object of wish (without any qualifying epithet), but that what seems good is object of wish to each man. The good man, then, wishes for the real object of wish; but what the bad man wishes for may be anything whatever; just as, with regard to the body, those who are in good condition find those things healthy that are really healthy, while those who are diseased find other things healthy (and it is just the same with things bitter, sweet, hot, heavy, etc.): for the good or ideal man judges each case correctly, and in each case what is true seems true to him.
For, corresponding to each of our trained faculties, there is a special form of the noble and the pleasant, and perhaps there is nothing so distinctive of the good or ideal man as the power he has of discerning these special forms in each case, being himself, as it were, their standard and measure.
What misleads people seems to be in most cases pleasure; it seems to be a good thing, even when it is not. So they choose what is pleasant as good, and shun pain as evil.