Of Vice and Sin Considered in Themselves

I answer that, Two things may be considered in virtue—the essence of virtue, and that to which virtue is ordained. In the essence of virtue we may consider something directly, and we may consider something consequently. Virtue implies directly a disposition whereby the subject is well disposed according to the mode of its nature: wherefore the Philosopher says (Phys. vii, text. 17) that "virtue is a disposition of a perfect thing to that which is best; and by perfect I mean that which is disposed according to its nature." That which virtue implies consequently is that it is a kind of goodness: because the goodness of a thing consists in its being well disposed according to the mode of its nature. That to which virtue is directed is a good act, as was shown above (Q. 56, A. 3).

Accordingly three things are found to be contrary to virtue. One of these is sin, which is opposed to virtue in respect of that to which virtue is ordained: since, properly speaking, sin denotes an inordinate act; even as an act of virtue is an ordinate and due act: in respect of that which virtue implies consequently, viz. that it is a kind of goodness, the contrary of virtue is malice: while in respect of that which belongs to the essence of virtue directly, its contrary is vice: because the vice of a thing seems to consist in its not being disposed in a way befitting its nature: hence Augustine says (De Lib. Arb. iii): "Whatever is lacking for a thing's natural perfection may be called a vice."

I answer that, As stated above (A. 1), vice is contrary to virtue. Now the virtue of a thing consists in its being well disposed in a manner befitting its nature, as stated above (A. 1). Hence the vice of any thing consists in its being disposed in a manner not befitting its nature, and for this reason is that thing "vituperated," which word is derived from "vice" according to Augustine (De Lib. Arb. iii, 14).

But it must be observed that the nature of a thing is chiefly the form from which that thing derives its species. Now man derives his species from his rational soul: and consequently whatever is contrary to the order of reason is, properly speaking, contrary to the nature of man, as man; while whatever is in accord with reason, is in accord with the nature of man, as man. Now "man's good is to be in accord with reason, and his evil is to be against reason," as Dionysius states (Div. Nom. iv). Therefore human virtue, which makes a man good, and his work good, is in accord with man's nature, for as much as it accords with his reason: while vice is contrary to man's nature, in so far as it is contrary to the order of reason.

I answer that, A habit stands midway between power and act. Now it is evident that both in good and in evil, act precedes power, as stated in Metaph. ix, 19. For it is better to do well than to be able to do well, and in like manner, it is more blameworthy to do evil, than to be able to do evil: whence it also follows that both in goodness and in badness, habit stands midway between power and act, so that, to wit, even as a good or evil habit stands above the corresponding power in goodness or in badness, so does it stand below the corresponding act. This is also made clear from the fact that a habit is not called good or bad, save in so far as it induces to a good or bad act: wherefore a habit is called good or bad by reason of the goodness or badness of its act: so that an act surpasses its habit in goodness or badness, since "the cause of a thing being such, is yet more so."

I answer that, Sin is compared to virtue, as evil act to good habit. Now the position of a habit in the soul is not the same as that of a form in a natural thing. For the form of a natural thing produces, of necessity, an operation befitting itself; wherefore a natural form is incompatible with the act of a contrary form: thus heat is incompatible with the act of cooling, and lightness with downward movement (except perhaps violence be used by some extrinsic mover): whereas the habit that resides in the soul, does not, of necessity, produce its operation, but is used by man when he wills. Consequently man, while possessing a habit, may either fail to use the habit, or produce a contrary act; and so a man having a virtue may produce an act of sin. And this sinful act, so long as there is but one, cannot corrupt virtue, if we compare the act to the virtue itself as a habit: since, just as habit is not engendered by one act, so neither is it destroyed by one act as stated above (Q. 63, A. 2, ad 2). But if we compare the sinful act to the cause of the virtues, then it is possible for some virtues to be destroyed by one sinful act. For every mortal sin is contrary to charity, which is the root of all the infused virtues, as virtues; and consequently, charity being banished by one act of mortal sin, it follows that all the infused virtues are expelled as virtues. And I say [this] on account of faith and hope, whose habits remain unquickened after mortal sin, so that they are no longer virtues. On the other hand, since venial sin is neither contrary to charity, nor banishes it, as a consequence, neither does it expel the other virtues. As to the acquired virtues, they are not destroyed by one act of any kind of sin.

Accordingly, mortal sin is incompatible with the infused virtues, but is consistent with acquired virtue: while venial sin is compatible with virtues, whether infused or acquired.

I answer that, The reason for urging this question has reference to the sin of omission, about which there have been various opinions. For some say that in every sin of omission there is some act, either interior or exterior—interior, as when a man wills not to go to church, when he is bound to go—exterior, as when a man, at the very hour that he is bound to go to church (or even before), occupies himself in such a way that he is hindered from going. This seems, in a way, to amount to the same as the first, for whoever wills one thing that is incompatible with this other, wills, consequently, to go without this other: unless, perchance, it does not occur to him, that what he wishes to do, will hinder him from that which he is bound to do, in which case he might be deemed guilty of negligence. On the other hand, others say, that a sin of omission does not necessarily suppose an act: for the mere fact of not doing what one is bound to do is a sin.

Now each of these opinions has some truth in it. For if in the sin of omission we look merely at that in which the essence of the sin consists, the sin of omission will be sometimes with an interior act, as when a man wills not to go to church: while sometimes it will be without any act at all, whether interior or exterior, as when a man, at the time that he is bound to go to church, does not think of going or not going to church.

If, however, in the sin of omission, we consider also the causes, or occasions of the omission, then the sin of omission must of necessity include some act. For there is no sin of omission, unless we omit what we can do or not do: and that we turn aside so as not to do what we can do or not do, must needs be due to some cause or occasion, either united with the omission or preceding it. Now if this cause be not in man's power, the omission will not be sinful, as when anyone omits going to church on account of sickness: but if the cause or occasion be subject to the will, the omission is sinful; and such cause, in so far as it is voluntary, must needs always include some act, at least the interior act of the will: which act sometimes bears directly on the omission, as when a man wills not to go to church, because it is too much trouble; and in this case this act, of its very nature, belongs to the omission, because the volition of any sin whatever, pertains, of itself, to that sin, since voluntariness is essential to sin. Sometimes, however, the act of the will bears directly on something else which hinders man from doing what he ought, whether this something else be united with the omission, as when a man wills to play at the time he ought to go to church—or, precede the omission, as when a man wills to sit up late at night, the result being that he does not go to church in the morning. In this case the act, interior or exterior, is accidental to the omission, since the omission follows outside the intention, and that which is outside the intention is said to be accidental (Phys. ii, text. 49, 50). Wherefore it is evident that then the sin of omission has indeed an act united with, or preceding the omission, but that this act is accidental to the sin of omission.

Now in judging about things, we must be guided by that which is proper to them, and not by that which is accidental: and consequently it is truer to say that a sin can be without any act; else the circumstantial acts and occasions would be essential to other actual sins.

I answer that, As was shown above (A. 1), sin is nothing else than a bad human act. Now that an act is a human act is due to its being voluntary, as stated above (Q. 1, A. 1), whether it be voluntary, as being elicited by the will, e.g. to will or to choose, or as being commanded by the will, e.g. the exterior actions of speech or operation. Again, a human act is evil through lacking conformity with its due measure: and conformity of measure in a thing depends on a rule, from which if that thing depart, it is incommensurate. Now there are two rules of the human will: one is proximate and homogeneous, viz. the human reason; the other is the first rule, viz. the eternal law, which is God's reason, so to speak. Accordingly Augustine (Contra Faust. xxii, 27) includes two things in the definition of sin; one, pertaining to the substance of a human act, and which is the matter, so to speak, of sin, when he says "word, deed, or desire"; the other, pertaining to the nature of evil, and which is the form, as it were, of sin, when he says, "contrary to the eternal law."