Some philosophers think that no pleasure is a good; others think that only some pleasures are good and that most are bad; and yet others think that all pleasures are good, even though they are not the supreme good. However, none of their many arguments is able to prove that pleasure is not a good or even the supreme good, this for three principle reasons. (1) The good or bad need not be simply good or bad, but good or bad for a certain person or at a certain time. (2) The good or bad is either an activity (energeia) or a state (hexis), and there are pleasures that come from being restored to our natural state, and pleasures – such as the pleasure of contemplation – that come from being in our natural state. (3) Pleasures are not processes but activities; as activities, they are also ends in themselves. It is true that some pleasures are harmful, but this is only in a limited sense. On the other hand, the higher pleasures that are enjoyed by the temperate person are not harmful in any sense. If it can be agreed that pain is bad and to be avoided, then it can also be agreed that pleasure (the contrary of pain) is good and to be sought out. All men think that the happy life is pleasurable, and cannot conceive of an ideal of happiness that is divorced from pleasure. All animals avoid pain and pursue pleasure, and if some of the pleasures that they pursue are bad, this need not imply that all pleasures are bad or even that the supreme good is not some pleasure. Things that are pleasurable incidentally in that they act as restoratives can be contrasted to things that are pleasurable by nature in that they stimulate the action of the healthy nature. These natural or higher pleasures do not admit of pain and therefore neither of excess. If the majority of men prefer incidental pleasures to natural or higher pleasures, this is because of man’s vicious nature. In truth, pleasure is found more in rest than in movement, and God perpetually enjoys a single and unalloyed pleasure.
– Nicomachean Ethics, Book VII, Chapters 11-14