Objection 1: It would seem that pleasure does not cause desire for itself. Because all movement ceases when repose is reached. But pleasure is, as it were, a certain repose of the movement of desire, as stated above ([1285]Q[23], A[4];[1286] Q[25], A[2]). Therefore the movement of desire ceases when pleasure is reached. Therefore pleasure does not cause desire.

Objection 2: Further, a thing does not cause its contrary. But pleasure is, in a way, contrary to desire, on the part of the object: since desire regards a good which is not yet possessed, whereas pleasure regards the good that is possessed. Therefore pleasure does not cause desire for itself.

Objection 3: Further, distaste is incompatible with desire. But pleasure often causes distaste. Therefore it does not cause desire.

On the contrary, Our Lord said (Jn.4:13): "Whosoever drinketh of this water, shall thirst again": where, according to Augustine (Tract. xv in Joan.), water denotes pleasures of the body.

I answer that, Pleasure can be considered in two ways; first, as existing in reality; secondly, as existing in the memory. Again thirst, or desire, can be taken in two ways; first, properly, as denoting a craving for something not possessed; secondly, in general, as excluding distaste.

Considered as existing in reality, pleasure does not of itself cause thirst or desire for itself, but only accidentally; provided we take thirst or desire as denoting a craving for some thing not possessed: because pleasure is an emotion of the appetite in respect of something actually present. But it may happen that what is actually present is not perfectly possessed: and this may be on the part of the thing possessed, or on the part of the possessor. On the part of the thing possessed, this happens through the thing possessed not being a simultaneous whole; wherefore one obtains possession of it successively, and while taking pleasure in what one has, one desires to possess the remainder: thus if a man is pleased with the first part of a verse, he desires to hear the second part, as Augustine says (Confess. iv, 11). In this way nearly all bodily pleasures cause thirst for themselves, until they are fully realized, because pleasures of this kind arise from some movement: as is evident in pleasures of the table. On the part of the possessor, this happens when a man possesses a thing which is perfect in itself, yet does not possess it perfectly, but obtains possession of it little by little. Thus in this life, a faint perception of Divine knowledge affords us delight, and delight sets up a thirst or desire for perfect knowledge; in which sense we may understand the words of Ecclus.24:29: "They that drink me shall yet thirst."

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. Spiritual pleasures, on the contrary, do not exceed the natural mode of being, but perfect nature. Hence when their point of perfection is reached, then do they afford the greatest delight: except, perchance, accidentally, in so far as the work of contemplation is accompanied by some operation of the bodily powers, which tire from protracted activity. And in this sense also we may understand those words of Ecclus.24:29: "They that drink me shall yet thirst": for, even of the angels, who know God perfectly, and delight in Him, it is written (1 Pet.1:12) that they "desire to look at Him."

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 to Objection 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 to Objection 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 to Objection 3: Pleasures cause distaste in one way, desire in another, as stated above.