I answer that, As stated above (Articles [1],2), the inordinateness of anger is considered in a twofold respect, namely with regard to an undue object, and with regard to an undue mode of being angry. As to the appetible object which it desires, anger would seem to be the least of sins, for anger desires the evil of punishment for some person, under the aspect of a good that is vengeance. Hence on the part of the evil which it desires the sin of anger agrees with those sins which desire the evil of our neighbor, such as envy and hatred; but while hatred desires absolutely another's evil as such, and the envious man desires another's evil through desire of his own glory, the angry man desires another's evil under the aspect of just revenge. Wherefore it is evident that hatred is more grievous than envy, and envy than anger: since it is worse to desire evil as an evil, than as a good; and to desire evil as an external good such as honor or glory, than under the aspect of the rectitude of justice. On the part of the good, under the aspect of which the angry man desires an evil, anger concurs with the sin of concupiscence that tends to a good. In this respect again, absolutely speaking. the sin of anger is apparently less grievous than that of concupiscence, according as the good of justice, which the angry man desires, is better than the pleasurable or useful good which is desired by the subject of concupiscence. Wherefore the Philosopher says (Ethic. vii, 4) that "the incontinent in desire is more disgraceful than the incontinent in anger."
On the other hand, as to the inordinateness which regards the mode of being angry, anger would seem to have a certain pre-eminence on account of the strength and quickness of its movement, according to Prov. 27:4, "Anger hath no mercy, nor fury when it breaketh forth: and who can bear the violence of one provoked?" Hence Gregory says (Moral. v, 45): "The heart goaded by the pricks of anger is convulsed, the body trembles, the tongue entangles itself, the face is inflamed, the eyes are enraged and fail utterly to recognize those whom we know: the tongue makes sounds indeed, but there is no sense in its utterance."