Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 24 ; Q. 26 de Verit., a. 6 and 7.

178. Principle I. Passions also can contribute to the morality of human acts¹, and indeed not only for the morality of interior but also of exterior acts.

For passions can be considered in a twofold way:

1° as to the being of nature or the physical, inasmuch as they are common to us with brutes, and so are physically good, since they are implanted by God;

2° as to moral being, inasmuch as they are proper to man, and so

a) they are not of themselves bad, nor good, but indifferent: for the movements of the sensitive appetite are not of themselves from reason, nor therefore human;

b) if they are considered as subject to the command of reason and will, so they are good or bad, inasmuch as they are voluntary, whether directly inasmuch as they are commanded by the will, or indirectly inasmuch as they are not prevented by it.

It is proved: 1) « For the sensitive appetite is nearer to reason and will than the external members ». But the acts of the external members are morally good or bad according as they are voluntary. Therefore much more the passions themselves, according as they are voluntary, are morally good or bad (a. 1).

2. From the Scriptures, (which a) commend certain passions (Ps. IV, 5; II Cor. VII, 9; Rom. XII, 15); b) assert that they are found in Christ although bound by reason (Mc. XXVI, 38; Mc. III, 5; XIV, 33; Lc. XIX, 41; Ioh. XI, 33); c) and praise men for them or reprove them for their absence (Exod. XXXII, 19; Num. XXV, 11; I Reg. II-III).

Whence to be ruled by passions is not evil because they are in themselves evil, but because the order is inverted, according to which the higher part ought to rule the lower; but it is good to rule them, provided this is conformably to the order of reason (a. 2).

179. Corollary. — Therefore the passions, if they are considered as to their natural being, are not morally good or bad according to species, but indifferent; but if they are considered as regulated by reason, they can be, just as external acts, according to species good or bad, according as their proper object is fitting for reason or unfitting: thus e. g. shame or fear of base things is good, and envy or sadness at another's good is bad (a. 4).

180. Principle II. Voluntary passions increase the goodness or malice of the act. — It is proved: The more perfect the good of reason or moral good is, the more it is derived to the many things that are fitting for man; whence it also pertains to moral perfection that external acts be directed by reason. But the sensitive appetite can obey reason. Therefore it pertains to moral perfection that the passions be regulated by reason. Just as therefore it is better that man will the good and do it by an exterior act, so it is better that he be moved to the good, both according to the will and according to the sensitive appetite, for promptness in operating (a. 3).

Which, however, is to be understood of passions willed, which are chosen and commanded by the will (in the respectively diverse way in which it must be done for good and evil; cf. n. 146). For a passion which moves man toward a sensible good, if it precedes the will, diminishes liberty and consequently goodness and malice; — if it follows by redundance, it is not the cause but the mere effect of the will: not the cause namely but « the sign of a more intense will (or of a greater voluntary), and so indicates greater moral goodness » or malice; — if it follows by election, it adds to the goodness or malice (ad 1).