Whether venial sin is fittingly condivided with mortal sin?
Objection 1: It would seem that venial sin is unfittingly condivided with mortal sin. For Augustine says (Contra Faust. xxii, 27): "Sin is a word, deed or desire contrary to the eternal law." But the fact of being against the eternal law makes a sin to be mortal. Consequently every sin is mortal. Therefore venial sin is not condivided with mortal sin.
Objection 2: Further, the Apostle says (1 Cor. 10:31): "Whether you eat or drink, or whatever else you do; do all to the glory of God." Now whoever sins breaks this commandment, because sin is not done for God's glory. Consequently, since to break a commandment is to commit a mortal sin, it seems that whoever sins, sins mortally.
Objection 3: Further, whoever cleaves to a thing by love, cleaves either as enjoying it, or as using it, as Augustine states (De Doctr. Christ. i, 3,4). But no person, in sinning, cleaves to a mutable good as using it: because he does not refer it to that good which gives us happiness, which, properly speaking, is to use, according to Augustine (De Doctr. Christ. i, 3,4). Therefore whoever sins enjoys a mutable good. Now "to enjoy what we should use is human perverseness," as Augustine again says (Qq. lxxxiii, qu. 30). Therefore, since "perverseness" [*The Latin 'pervertere' means to overthrow, to destroy, hence 'perversion' of God's law is a mortal sin.] denotes a mortal sin, it seems that whoever sins, sins mortally.
Objection 4: Further, whoever approaches one term, from that very fact turns away from the opposite. Now whoever sins, approaches a mutable good, and, consequently turns away from the immutable good, so that he sins mortally. Therefore venial sin is unfittingly condivided with mortal sin.
On the contrary, Augustine says (Tract. xli in Joan.), that "a crime is one that merits damnation, and a venial sin, one that does not." But a crime denotes a mortal sin. Therefore venial sin is fittingly condivided with mortal sin.
I answer that, Certain terms do not appear to be mutually opposed, if taken in their proper sense, whereas they are opposed if taken metaphorically: thus "to smile" is not opposed to "being dry"; but if we speak of the smiling meadows when they are decked with flowers and fresh with green hues this is opposed to drought. In like manner if mortal be taken literally as referring to the death of the body, it does not imply opposition to venial, nor belong to the same genus. But if mortal be taken metaphorically, as applied to sin, it is opposed to that which is venial.
For sin, being a sickness of the soul, as stated above (Q 71, A 1, ad 3; Q 72, A 5; Q 74, A 9, ad 2), is said to be mortal by comparison with a disease, which is said to be mortal, through causing an irreparable defect consisting in the corruption of a principle, as stated above (Q 72, A 5). Now the principle of the spiritual life, which is a life in accord with virtue, is the order to the last end, as stated above (Q 72, A 5; Q 87, A 3): and if this order be corrupted, it cannot be repaired by any intrinsic principle, but by the power of God alone, as stated above (Q 87, A 3), because disorders in things referred to the end, are repaired through the end, even as an error about conclusions can be repaired through the truth of the principles. Hence the defect of order to the last end cannot be repaired through something else as a higher principle, as neither can an error about principles. Wherefore such sins are called mortal, as being irreparable. On the other hand, sins which imply a disorder in things referred to the end, the order to the end itself being preserved, are reparable. These sins are called venial: because a sin receives its acquittal [veniam] when the debt of punishment is taken away, and this ceases when the sin ceases, as explained above (Q 87, A 6).
Accordingly, mortal and venial are mutually opposed as reparable and irreparable: and I say this with reference to the intrinsic principle, but not to the Divine power, which can repair all diseases, whether of the body or of the soul. Therefore venial sin is fittingly condivided with mortal sin.
Reply to Objection 1: The division of sin into venial and mortal is not a division of a genus into its species which have an equal share of the generic nature: but it is the division of an analogous term into its parts, of which it is predicated, of the one first, and of the other afterwards. Consequently the perfect notion of sin, which Augustine gives, applies to mortal sin. On the other hand, venial sin is called a sin, in reference to an imperfect notion of sin, and in relation to mortal sin: even as an accident is called a being, in relation to substance, in reference to the imperfect notion of being. For it is not "against" the law, since he who sins venially neither does what the law forbids, nor omits what the law prescribes to be done; but he acts "beside" the law, through not observing the mode of reason, which the law intends.
Reply to Objection 2: This precept of the Apostle is affirmative, and so it does not bind for all times. Consequently everyone who does not actually refer all his actions to the glory of God, does not therefore act against this precept. In order, therefore, to avoid mortal sin each time that one fails actually to refer an action to God's glory, it is enough to refer oneself and all that one has to God habitually. Now venial sin excludes only actual reference of the human act to God's glory, and not habitual reference: because it does not exclude charity, which refers man to God habitually. Therefore it does not follow that he who sins venially, sins mortally.
Reply to Objection 3: He that sins venially, cleaves to temporal good, not as enjoying it, because he does not fix his end in it, but as using it, by referring it to God, not actually but habitually.
Reply to Objection 4: Mutable good is not considered to be a term in contraposition to the immutable good, unless one's end is fixed therein: because what is referred to the end has not the character of finality.
I–II · Q. 88, Art. 2: Whether mortal and venial sin differ generically?
Whether mortal and venial sin differ generically?
Objection 1: It would seem that venial and mortal sin do not differ generically, so that some sins be generically mortal, and some generically venial. Because human acts are considered to be generically good or evil according to their matter or object, as stated above (Q 18, A 2). Now either mortal or venial sin may be committed in regard to any object or matter: since man can love any mutable good, either less than God, which may be a venial sin, or more than God, which is a mortal sin. Therefore venial and mortal sin do not differ generically.
Objection 2: Further, as stated above (A 1; Q 72, A 5; Q 87, A 3), a sin is called mortal when it is irreparable, venial when it can be repaired. Now irreparability belongs to sin committed out of malice, which, according to some, is irremissible: whereas reparability belongs to sins committed through weakness or ignorance, which are remissible. Therefore mortal and venial sin differ as sin committed through malice differs from sin committed through weakness or ignorance. But, in this respect, sins differ not in genus but in cause, as stated above (Q 77, A 8, ad 1). Therefore venial and mortal sin do not differ generically.
Objection 3: Further, it was stated above (Q 74, A 3, ad 3; A 10) that sudden movements both of the sensuality and of the reason are venial sins. But sudden movements occur in every kind of sin. Therefore no sins are generically venial.
On the contrary, Augustine, in a sermon on Purgatory (De Sanctis, serm. xli), enumerates certain generic venial sins, and certain generic mortal sins.
I answer that, Venial sin is so called from "venia" [pardon]. Consequently a sin may be called venial, first of all, because it has been pardoned: thus Ambrose says that "penance makes every sin venial": and this is called venial "from the result." Secondly, a sin is called venial because it does not contain anything either partially or totally, to prevent its being pardoned: partially, as when a sin contains something diminishing its guilt, e.g. a sin committed through weakness or ignorance: and this is called venial "from the cause": totally, through not destroying the order to the last end, wherefore it deserves temporal, but not everlasting punishment. It is of this venial sin that we wish to speak now.
For as regards the first two, it is evident that they have no determinate genus: whereas venial sin, taken in the third sense, can have a determinate genus, so that one sin may be venial generically, and another generically mortal, according as the genus or species of an act is determined by its object. For, when the will is directed to a thing that is in itself contrary to charity, whereby man is directed to his last end, the sin is mortal by reason of its object. Consequently it is a mortal sin generically, whether it be contrary to the love of God, e.g. blasphemy, perjury, and the like, or against the love of one's neighbor, e.g. murder, adultery, and such like: wherefore such sins are mortal by reason of their genus. Sometimes, however, the sinner's will is directed to a thing containing a certain inordinateness, but which is not contrary to the love of God and one's neighbor, e.g. an idle word, excessive laughter, and so forth: and such sins are venial by reason of their genus.
Nevertheless, since moral acts derive their character of goodness and malice, not only from their objects, but also from some disposition of the agent, as stated above (Q 18, AA 4,6), it happens sometimes that a sin which is venial generically by reason of its object, becomes mortal on the part of the agent, either because he fixes his last end therein, or because he directs it to something that is a mortal sin in its own genus; for example, if a man direct an idle word to the commission of adultery. In like manner it may happen, on the part of the agent, that a sin generically mortal becomes venial, by reason of the act being imperfect, i.e. not deliberated by reason, which is the proper principle of an evil act, as we have said above in reference to sudden movements of unbelief.
Reply to Objection 1: The very fact that anyone chooses something that is contrary to divine charity, proves that he prefers it to the love of God, and consequently, that he loves it more than he loves God. Hence it belongs to the genus of some sins, which are of themselves contrary to charity, that something is loved more than God; so that they are mortal by reason of their genus.
Reply to Objection 2: This argument considers those sins which are venial from their cause.
Reply to Objection 3: This argument considers those sins which are venial by reason of the imperfection of the act.