Nicomachean Ethics, Book X
1) There are conflicting views of pleasure.
2) Some say it is the chief good, but it cannot be because we can make it better by addition of other things to it, such as wisdom. It is, however, aimed at by all creatures, and so there must some relation to good.
3) Pleasure is state of being not an activity. There are different kinds of pleasure. Therefore, just because there are disgraceful pleasures, pursued by vicious people, does not mean that pleasure is bad.
4) Pleasure is not a movement, but is whole in itself. It exists when the organ of perception is healthy and the thing perceived is beautiful. Pleasure accompanies activity of sense, and nobody is continuously active.
5) As the activities that bring pleasure are different, do pleasures differ in kind and value. As in other respects, we consider that which the good man finds pleasurable to be the proper kind of pleasure -- we judge by the faculty of the good man.
6) Happiness is not a state, but an activity. It is not amusement, though some believe that it is, because the good man pursues amusement for relaxation, for the sake of activity, he does not exert himself in order to be amused. It lies in virtuous activity, and is pursued as an end in itself.
7) Happiness is activity in accordance with virtue, and so it will be in accordance with the highest virtue, which is contemplative. Reason is the best part of man, the objects of reason are the best of knowable objects, and we can contemplate truth more continuously than we can do anything else. For man, life according to reason is best and most pleasant, because reason is the unique function of man.
8) Contemplation is a self-sufficient activity. We consider the gods to be more blessed than man, and the gods engage in leisurely activity, not in work or justice or running risks (bravery) or liberality. Man's nature, however, is not wholly self-sufficient, and so even the contemplative man will need to act in the societal sphere, and so will need to practice other virtues.
9) Now that our arguments are done, we must be concerned with how to cultivate virtue -- we need right law.