Reply to Objection 3: All things seek pleasure in the same way as they seek good: since pleasure is the repose of the appetite in good. But, just as it happens that not every good which is desired, is of itself and verily good; so not every pleasure is of itself and verily good.
Whether any pleasure is the greatest good?
Objection 1: It would seem that no pleasure is the greatest good. Because nothing generated is the greatest good: since generation cannot be the last end. But pleasure is a consequence of generation: for the fact that a thing takes pleasure is due to its being established in its own nature, as stated above (Q[31], A[1]). Therefore no pleasure is the greatest good.
Objection 2: Further, that which is the greatest good cannot be made better by addition. But pleasure is made better by addition; since pleasure together with virtue is better than pleasure without virtue. Therefore pleasure is not the greatest good.
Objection 3: Further, that which is the greatest good is universally good, as being good of itself: since that which is such of itself is prior to and greater than that which is such accidentally. But pleasure is not universally good, as stated above (A[2]). Therefore pleasure is not the greatest good.
On the contrary, Happiness is the greatest good: since it is the end of man's life. But Happiness is not without pleasure: for it is written ( Ps. 15:11 ): "Thou shalt fill me with joy with Thy countenance; at Thy right hand are delights even to the end."
I answer that, Plato held neither with the Stoics, who asserted that all pleasures are evil, nor with the Epicureans, who maintained that all pleasures are good; but he said that some are good, and some evil; yet, so that no pleasure be the sovereign or greatest good. But, judging from his arguments, he fails in two points. First, because, from observing that sensible and bodily pleasure consists in a certain movement and "becoming," as is evident in satiety from eating and the like; he concluded that all pleasure arises from some "becoming" and movement: and from this, since "becoming" and movement are the acts of something imperfect, it would follow that pleasure is not of the nature of ultimate perfection. But this is seen to be evidently false as regards intellectual pleasures: because one takes pleasure, not only in the "becoming" of knowledge, for instance, when one learns or wonders, as stated above (Q[32], A[8], ad 2); but also in the act of contemplation, by making use of knowledge already acquired.
Secondly, because by greatest good he understood that which is the supreme good simply, i.e. the good as existing apart from, and unparticipated by, all else, in which sense God is the Supreme Good; whereas we are speaking of the greatest good in human things. Now the greatest good of everything is its last end. And the end, as stated above (Q[1], A[8]; Q[2], A[7]) is twofold; namely, the thing itself, and the use of that thing; thus the miser's end is either money or the possession of money. Accordingly, man's last end may be said to be either God Who is the Supreme Good simply; or the enjoyment of God, which implies a certain pleasure in the last end. And in this sense a certain pleasure of man may be said to be the greatest among human goods.
Reply to Objection 1: Not every pleasure arises from a "becoming"; for some pleasures result from perfect operations, as stated above. Accordingly nothing prevents some pleasure being the greatest good, although every pleasure is not such.
Reply to Objection 2: This argument is true of the greatest good simply, by participation of which all things are good; wherefore no addition can make it better: whereas in regard to other goods, it is universally true that any good becomes better by the addition of another good. Moreover it might be said that pleasure is not something extraneous to the operation of virtue, but that it accompanies it, as stated in Ethic. i, 8.
Reply to Objection 3: That pleasure is the greatest good is due not to the mere fact that it is pleasure, but to the fact that it is perfect repose in the perfect good. Hence it does not follow that every pleasure is supremely good, or even good at all. Thus a certain science is supremely good, but not every science is.
Whether pleasure is the measure or rule by which to judge of moral good or evil?
Objection 1: It would seem that pleasure is not the measure or rule of moral good and evil. Because "that which is first in a genus is the measure of all the rest" (Metaph. x, 1). But pleasure is not the first thing in the moral genus, for it is preceded by love and desire. Therefore it is not the rule of goodness and malice in moral matters.
Objection 2: Further, a measure or rule should be uniform; hence that movement which is the most uniform, is the measure and rule of all movements (Metaph. x, 1). But pleasures are various and multiform: since some of them are good, and some evil. Therefore pleasure is not the measure and rule of morals.
Objection 3: Further, judgment of the effect from its cause is more certain than judgment of cause from effect. Now goodness or malice of operation is the cause of goodness or malice of pleasure: because "those pleasures are good which result from good operations, and those are evil which arise from evil operations," as stated in Ethic. x, 5. Therefore pleasures are not the rule and measure of moral goodness and malice.
On the contrary, Augustine, commenting on Ps. 7:10 "The searcher of hearts and reins is God," says: "The end of care and thought is the pleasure which each one aims at achieving." And the Philosopher says (Ethic. vii, 11) that "pleasure is the architect," i.e. the principal, "end [*St. Thomas took "finis" as being the nominative, whereas it is the genitive---; and the Greek reads "He" (i.e. the political philosopher), "is the architect of the end."], in regard to which, we say absolutely that this is evil, and that, good."
I answer that, Moral goodness or malice depends chiefly on the will, as stated above (Q[20], A[1]); and it is chiefly from the end that we discern whether the will is good or evil. Now the end is taken to be that in which the will reposes: and the repose of the will and of every appetite in the good is pleasure. And therefore man is reckoned to be good or bad chiefly according to the pleasure of the human will; since that man is good and virtuous, who takes pleasure in the works of virtue; and that man evil, who takes pleasure in evil works.
On the other hand, pleasures of the sensitive appetite are not the rule of moral goodness and malice; since food is universally pleasurable to the sensitive appetite both of good and of evil men. But the will of the good man takes pleasure in them in accordance with reason, to which the will of the evil man gives no heed.
Reply to Objection 1: Love and desire precede pleasure in the order of generation. But pleasure precedes them in the order of the end, which serves a principle in actions; and it is by the principle, which is the rule and measure of such matters, that we form our judgment.
Reply to Objection 2: All pleasures are uniform in the point of their being the repose of the appetite in something good: and in this respect pleasure can be a rule or measure. Because that man is good, whose will rests in the true good: and that man evil, whose will rests in evil.
Reply to Objection 3: Since pleasure perfects operation as its end, as stated above (Q[33], A[4]); an operation cannot be perfectly good, unless there be also pleasure in good: because the goodness of a thing depends on its end. And thus, in a way, the goodness of the pleasure is the cause of goodness in the operation.