Thomas Aquinas

“ Now it is evident that every appetite, even the natural appetite, tends with greater force to repel that which is contrary to it, if it be present: hence we see that hot water freezes harder, as though the cold acted with greater force on the hot object. Since then the appetitive movement of anger is caused by some injury inflicted, as by a contrary that is present; it follows that the appetite tends with great force to repel the injury by the desire of vengeance; and hence ensues great vehemence and impetuosity in the movement of anger. ”

“ Time, of necessity, weakens all those things, the causes of which are impaired by time. Now it is evident that memory is weakened by time; for things which happened long ago easily slip from our memory. But anger is caused by the memory of a wrong done. Consequently the cause of anger is impaired little by little as time goes on, until at length it vanishes altogether. Moreover a wrong seems greater when it is first felt; and our estimate thereof is gradually lessened the further the sense of present wrong recedes into the past. ”

“ As stated above (ad 1) , the movement of anger begins in the reason, wherefore the juxtaposition of one contrary with another facilitates the judgment of reason, on the same grounds as it increases anger. For when a man who is possessed of honor or wealth, suffers a loss therein, the loss seems all the greater, both on account of the contrast, and because it was unforeseen. Consequently it causes greater grief: just as a great good, through being received unexpectedly, causes greater delight. And in proportion to the increase of the grief that precedes, anger is increased also. ”

“ Every power that is divided in itself is weakened. Consequently if a man being already angry with one, becomes angry with another, by this very fact his anger with the former is weakened. Especially is this so if his anger in the second case be greater: because the wrong done which aroused his former anger, will, in comparison with the second wrong, which is reckoned greater, seem to be of little or no account. ”

“ Desire, on the other hand, is said to lie low and to be cunning, because, in many cases, the pleasurable things that are desired, savor of shame and voluptuousness, wherein man wishes not to be seen. But in those things that savor of manliness and excellence, such as matters of vengeance, man seeks to be in the open. ”

“ The same applies to love, so long as the cause of love is in the memory alone; wherefore the Philosopher says (Ethic. viii, 5) that "if a friend's absence lasts long, it seems to make men forget their friendship." But in the presence of a friend, the cause of friendship is continually being multiplied by time: wherefore the friendship increases: and the same would apply to anger, were its cause continually multiplied. ”

“ Art. 1 - Whether anger causes pleasure? Objection 1: It would seem that anger does not cause pleasure. Because sorrow excludes pleasure. But anger is never without sorrow, since, as stated in Ethic. vii, 6, "everyone that acts from anger, acts with pain." Therefore anger does not cause pleasure.
Objection 2: Further, the Philosopher says (Ethic. iv, 5) that "vengeance makes anger to cease, because it substitutes pleasure for pain": whence we may gather that the angry man derives pleasure from vengeance, and that vengeance quells his anger. ”