Obj. 2:  Further, the more a man’s action is like to God, the better it is:  hence the Apostle says (Eph. 5:1):  “Be ye followers of God, as most dear children.”  But “God and the holy angels feel no anger when they punish . . . no fellow-feeling with misery when they relieve the unhappy,” as Augustine says (De Civ.  Dei ix, 5).  Therefore it is better to do such like deeds without than with a passion of the soul.

Obj. 3:  Further, just as moral evil depends on its relation to reason, so also does moral good.  But moral evil is lessened by passion:  for he sins less, who sins from passion, than he who sins deliberately.  Therefore he does a better deed, who does well without passion, than he who does with passion.

On the contrary, Augustine says (De Civ.  Dei ix, 5) that “the passion of pity is obedient to reason, when pity is bestowed without violating right, as when the poor are relieved, or the penitent forgiven.”  But nothing that is obedient to reason lessens the moral good.  Therefore a passion of the soul does not lessen moral good.

I answer that, As the Stoics held that every passion of the soul is evil, they consequently held that every passion of the soul lessens the goodness of an act; since the admixture of evil either destroys good altogether, or makes it to be less good.  And this is true indeed, if by passions we understand none but the inordinate movements of the sensitive appetite, considered as disturbances or ailments.  But if we give the name of passions to all the movements of the sensitive appetite, then it belongs to the perfection of man’s good that his passions be moderated by reason.  For since man’s good is founded on reason as its root, that good will be all the more perfect, according as it extends to more things pertaining to man.  Wherefore no one questions the fact that it belongs to the perfection of moral good, that the actions of the outward members be controlled by the law of reason.  Hence, since the sensitive appetite can obey reason, as stated above (Q. 17, A. 7), it belongs to the perfection of moral or human good, that the passions themselves also should be controlled by reason.

Accordingly just as it is better that man should both will good and do it in his external act; so also does it belong to the perfection of moral good, that man should be moved unto good, not only in respect of his will, but also in respect of his sensitive appetite; according to Ps. 83:3:  “My heart and my flesh have rejoiced in the living God”:  where by “heart” we are to understand the intellectual appetite, and by “flesh” the sensitive appetite.