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.
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.
Objection 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.
Objection 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."
I answer that, As is stated in Ethic. x, 5, "appropriate pleasures increase activity . . . whereas pleasures arising from other sources are impediments to activity." Accordingly there is a certain pleasure that is taken in the very act of reason, as when one takes pleasure in contemplating or in reasoning: and such pleasure does not hinder the act of reason, but helps it; because we are more attentive in doing that which gives us pleasure, and attention fosters activity.
On the other hand bodily pleasures hinder the use of reason in three ways. First, by distracting the reason. Because, as we have just observed, we attend much to that which pleases us. 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when the attention is firmly fixed on one thing, it is either weakened in respect of other things, or it is entirely withdrawn from them; and thus if the bodily pleasure be great, either it entirely hinders the use of reason, by concentrating the mind's attention on itself; or else it hinders it considerably. Secondly, by being contrary to reason. Because some pleasures, especially those that are in excess, are contrary to the order of reason: and in this sense the Philosopher says that "bodily pleasures destroy the estimate of prudence, but not the speculative estimate," to which they are not opposed, "for instance that the three angles of a triangle are together equal to two right angles." In the first sense, however, they hinder both estimates. Thirdly, by fettering the reason: in so far as bodily pleasure is followed by a certain alteration in the body, greater even than in the other passions, in proportion as the appetite is more vehemently affected towards a present than towards an absent thing. Now such bodily disturbances hinder the use of reason; as may be seen in the case of drunkards, in whom the use of reason is fettered or hindered.
Reply to Objection 1: Bodily pleasure implies indeed repose of the appetite in the object of pleasure; which repose is sometimes contrary to reason; but on the part of the body it always implies alteration. And in respect of both points, it hinders the use of reason.
Reply to Objection 2: The powers of the appetite and of apprehension are indeed distinct parts, but belonging to the one soul. Consequently when the soul is very intent on the action of one part, it is hindered from attending to a contrary act of the other part.
Reply to Objection 3: The use of reason requires the due use of the imagination and of the other sensitive powers, which are exercised through a bodily organ. Consequently alteration in the body hinders the use of reason, because it hinders the act of the imagination and of the other sensitive powers.
Whether pleasure perfects operation?
Objection 1: It would seem that pleasure does not perfect operation. For every human operation depends on the use of reason. But pleasure hinders the use of reason, as stated above (A[3]). Therefore pleasure does not perfect, but weakens human operation.
Objection 2: Further, nothing perfects itself or its cause. But pleasure is an operation (Ethic. vii, 12; x, 4), i.e. either in its essence or in its cause. Therefore pleasure does not perfect operation.
Objection 3: Further, if pleasure perfects operation, it does so either as end, or as form, or as agent. But not as end; because operation is not sought for the sake of pleasure, but rather the reverse, as stated above (Q[4], A[2]): nor as agent, because rather is it the operation that causes pleasure: nor again as form, because, according to the Philosopher (Ethic. x, 4), "pleasure does not perfect operation, as a habit does." Therefore pleasure does not perfect operation.
On the contrary, The Philosopher says (Ethic. x, 4) that "pleasure perfects operation."
I answer that, Pleasure perfects operation in two ways. First, as an end: not indeed according as an end is that on "account of which a thing is"; but according as every good which is added to a thing and completes it, can be called its end. And in this sense the Philosopher says (Ethic. x, 4) that "pleasure perfects operation . . . as some end added to it": that is to say, inasmuch as to this good, which is operation, there is added another good, which is pleasure, denoting the repose of the appetite in a good that is presupposed. Secondly, as agent; not indeed directly, for the Philosopher says (Ethic. x, 4) that "pleasure perfects operation, not as a physician makes a man healthy, but as health does": but it does so indirectly; inasmuch as the agent, through taking pleasure in his action, is more eagerly intent on it, and carries it out with greater care. And in this sense it is said in Ethic. x, 5 that "pleasures increase their appropriate activities, and hinder those that are not appropriate."
Reply to Objection 1: It is not every pleasure that hinders the act of reason, but only bodily pleasure; for this arises, not from the act of reason, but from the act of the concupiscible faculty, which act is intensified by pleasure. On the contrary, pleasure that arises from the act of reason, strengthens the use of reason.
Reply to Objection 2: As stated in Phys. ii, 3 two things may be causes of one another, if one be the efficient, the other the final cause. And in this way, operation is the efficient cause of pleasure, while pleasure perfects operation by way of final cause, as stated above.
The Reply to the Third Objection is evident for what has been said.