We proceed to the first article thus:

1. It seems that despair is not a sin. Augustine makes it clear that every sin turns to changeable good when it turns away from unchangeable good (De Lib. Arb., 1, cap. ult; 2, cap.19). But despair does not turn to changeable good. Hence it is not a sin.

2. Again, that which springs from a good root would not seem to be a sin, since "a good tree cannot bring forth evil fruit" (Matt.7:18). Now despair appears to spring from a good root, namely, from the fear of God, or from horror at the magnitude of one's own sins. Hence it is not a sin.

3. Again, if despair were a sin, it would be a sin for the damned to despair. Now their despair is not imputed to them as guilt, but rather as their damnation. Neither, then, is despair imputed to the wayfarer as guilt. Hence it is not a sin.

On the other hand: that by which men are led into sin would seem to be not only a sin, but a principle of sins. Such is despair, since the apostle says: "Who being past feeling have given themselves over unto lasciviousness, to work all uncleanness with greediness" (Eph.4:19). Despair is therefore not only a sin, but a principle of sins.

I answer: as the philosopher says in 6 Ethics 2, affirmation and negation in the intellect correspond to pursuit and avoidance in the appetite, while truth and falsity in the intellect correspond to what is good and to what is bad in the appetite. Hence every appetitive movement which corresponds to what is true in the intellect is good in itself, while every appetitive movement which corresponds to what is false in the intellect is bad in itself, and a sin. Now the true intellectual appreciation of God is of God as the source of man's salvation, and as the forgiver of sins, according to Ezek.18:23: "Have I any pleasure at all that the wicked should die? saith the Lord God; and not that he should return from his ways, and live?" That God denies pardon to a penitent sinner, or that he does not turn sinners to himself by means of justifying grace, is a false opinion. Accordingly, just as the movement of hope, which corresponds to the true appreciation of God, is laudable and virtuous, so the opposite movement of despair, which corresponds to the false opinion about God, is vicious and sinful.

On the first point: every mortal sin turns away from unchangeable good in some way, and turns to changeable good in one way or another. Since the theological virtues have God as their object, the sins opposed to them consist principally in turning away from unchangeable good, and consequentially in turning to changeable good. Other sins consist principally in turning to changeable good, and consequentially in turning away from unchangeable good. One who commits fornication does not intend to separate himself from God, but seeks delight in carnal pleasure, of which separation from God is the consequence.

On the second point: there are two ways in which a thing may spring from a root of virtue. It may spring directly from the virtue itself, as an action springs from its habit. No sin can spring from a virtuous root in this way. It is indeed in this sense that Augustine says: "no man can make bad use of a virtue" (2 De Lib. Arb.18, 19). But a thing may also spring from a virtue indirectly, or be occasioned by a virtue, and there is nothing to prevent a sin arising out of a virtue in this way. For example, men sometimes pride themselves on their virtues. As Augustine says: "Pride lies in wait for good works, so that they perish" (Epist.211 olim 109). In this way, despair can arise out of the fear of God, or out of horror at one's own sins, if a man makes bad use of these good things by turning them into an occasion for despair.

On the third point: the damned are not in a state which permits of hope, since it is impossible for them to return to blessedness. That they do not hope is consequently not imputed to them as guilt, but is part of their damnation. Neither is it imputed to a wayfarer as a sin, that he despairs of something which he is not born to attain, or of something which he is not under obligation to attain. It is not a sin, for example, if a doctor despairs of curing a sick man, or if one despairs of ever becoming rich.