Lastly, if we consider pleasure, not as existing in reality, but as existing in the memory, thus it has of itself a natural tendency to cause thirst and desire for itself: when, to wit, man returns to that disposition, in which he was when he experienced the pleasure that is past. But if he be changed from that disposition, the memory of that pleasure does not give him pleasure, but distaste: for instance, the memory of food in respect of a man who has eaten to repletion.
Reply Obj. 1: 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.
Reply Obj. 2: That which is possessed imperfectly, is possessed in one respect, and in another respect is not possessed. Consequently it may be the object of desire and pleasure at the same time.
Reply Obj. 3: Pleasures cause distaste in one way, desire in another, as stated above. ________________________
THIRD ARTICLE [I-II, Q. 33, Art. 3]
Whether Pleasure Hinders the Use of Reason?
Objection 1: It would seem that pleasure does not hinder the use of reason. Because repose facilitates very much the due use of reason: wherefore the Philosopher says (Phys. vii, 3) that "while we sit and rest, the soul is inclined to knowledge and prudence"; and it is written (Wis. 8:16): "When I go into my house, I shall repose myself with her," i.e. wisdom. But pleasure is a kind of repose. Therefore it helps rather than hinders the use of reason.
Obj. 2: Further, things which are not in the same subject though they be contraries, do not hinder one another. But pleasure is in the appetitive faculty, while the use of reason is in the apprehensive power. Therefore pleasure does not hinder the use of reason.
Obj. 3: Further, that which is hindered by another, seems to be moved, as it were, thereby. But the use of an apprehensive power moves pleasure rather than is moved by it: because it is the cause of pleasure. Therefore pleasure does not hinder the use of reason.
On the contrary, The Philosopher says (Ethic. vi, 5), that "pleasure destroys the estimate of prudence."