Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 86; q. 89, a. 1.

517. The second effect of sin is the guilt of fault i.e. the debt of repairing the offense inflicted on God by sin. For after actual sin is committed, man remains guilty of it; for when the voluntary act by which man withdraws from the light of reason and the law of God ceases, man does not for that reason immediately return to it, but for this is required a movement of the will contrary to the first movement, « just as if someone is at a distance from someone by some movement, when the movement ceases he does not immediately become near to him, but he must approach by returning through a contrary movement » (q. 86, a. 2). Whence the fault is imputed to man, until he has retracted it and obtained its pardon.

518. In mortal sin, the guilt of fault involves a state of habitual aversion from the last end, which is habitual sin: for it is impossible that man be guilty of aversion from the end and at the same time be converted to the end. Whence man remains turned away from God until he returns through conversion to God (Is. XVII; Mt. IX, 1-7; 12-13; Lk. VIII, 37-50; I John III, 5; Ps. L, 4). Habitual sin, in the natural order, would be only the privation of habitual ordination of reason (and will) to God; in the supernatural order however, since conversion and ordination to God is done through grace, the privation of habitual conversion to God is also the privation of habitual grace making pleasing (C. Trid. sess. 6, c. 15, can. 27; sess. 7, can. 6). It is not a mere punishment or effect, but a true habitual sin, because it is a voluntary and culpable inordination: voluntary, as foreseen by him who sins mortally and therefore willed at least in cause or indirectly; culpable, because he is bound to prevent and remove such inordination.

519. Mortal sin leaves a stain in the soul. — For our habitual ordination to God either through reason or through grace is the beauty of the soul: « the soul of man, says S. Thomas, a. 1, has a twofold brightness, one indeed from the shining of the natural light of reason by which it is directed in its acts, another from the shining of the divine light, namely of wisdom and grace ». Hence the privation of habitual ordination to God is at the same time the loss of due brightness and therefore a stain of the soul. Whence habitual sin and stain are not distinguished really but only in notion: inasmuch as it takes away order to God the last end, it is considered as habitual fault and separation from God; inasmuch however as it takes away the due beauty of the soul, it is considered as stain¹ (Jer. II, 22; Zech. XIII, 1; Ps. XIV; Ps. CXVIII; Ecclus. XXXI; Is. IV, 4; Ezech. XIV; XXXVI, 23; Josh. XXII, 17; John XIII, 10; Eph. V, 27; Tit. I, 15; I Cor. VI, 11; C. Trid. sess. 5, can. 2; prop. 56th of Baius).

It does not however follow that the stains of diverse sins do not differ among themselves, or that according as mortal sin does not cause a new stain, since habitual grace is already taken away by the first. For, as S. Thomas says, a. 1, ad 3, stain signifies the privation of the brightness of the soul in relation to the cause, which is the act of sin, and therefore the stains are several, diverse, and unequal according as the sins which induced them are several, diverse, and unequal, just as the shadows are diverse according to the diverse bodies impeding the light. Moreover a subsequent sin of itself is privative of grace and would take it away if it found it; and so it is a new cause of privation and thus a new stain.

520. What venial sin leaves behind. — Venial sin which is contrary to fervor, i.e. the exercise of charity, is imputed for guilt, until man, charity influencing, by an act of contrition or another equivalent which virtually contains displeasure of sin, has retracted it and so compensated its inordination. Since however it does not take away or diminish the habitual or permanent order to God and the habitual beauty of the soul (C. Trid. sess. 6, c. 11; sess. 14, c. 5), it follows that it does not induce a stain properly so called and remaining; inasmuch however as it impedes here and now the actual brightness coming from acts of virtue, it is sometimes improperly said, for one moment, to stain the soul².