Thomas Aquinas

“ When pleasure is perfect, then it includes complete rest; and the movement of desire, tending to what was not possessed, ceases. But when it is imperfect, then the desire, tending to what was not possessed, does not cease altogether. ”

“ Now when the attention is firmly fixed on one thing, it is either weakened in respect of other things, or it is entirely withdrawn from them; and thus if the bodily pleasure be great, either it entirely hinders the use of reason, by concentrating the mind's attention on itself ”

“ On the other hand, if by thirst or desire we understand the mere intensity of the emotion, that excludes distaste, thus more than all others spiritual pleasures cause thirst or desire for themselves. Because bodily pleasures become distasteful by reason of their causing an excess in the natural mode of being, when they are increased or even when they are protracted; as is evident in the case of pleasures of the table. This is why, when a man arrives at the point of perfection in bodily pleasures, he wearies of them, and sometimes desires another kind. ”

“ Further, when a thing expands it is enabled to receive more. But receiving pertains to desire, which is for something not yet possessed. Therefore expansion seems to belong to desire rather than to pleasure.
Objection 3: Further, contraction is contrary to expansion. But contraction seems to belong to pleasure, for the hand closes on that which we wish to grasp firmly: and such is the affection of appetite in regard to that which pleases it. Therefore expansion does not pertain to pleasure. ”

“ As a result of this apprehension, man perceives that he has attained a certain perfection, which is a magnitude of the spiritual order: and in this respect man's mind is said to be magnified or expanded by pleasure. The other requisite for pleasure is on the part of the appetitive power, which acquiesces in the pleasurable object, and rests therein, offering, as it were, to enfold it within itself. And thus man's affection is expanded by pleasure, as though it surrendered itself to hold within itself the object of its pleasure. ”