Thomas Aquinas, Disputed Questions on Truth (De Veritate)

1. No one has to ask of God what he can do by himself. But however much grace a person has, he must ask of God that he be freed from future sins. In the second Epistle to the Corinthians (13:7) the Apostle, addressing the faithful and the saints, accordingly says: "Now we pray God, that you may do no evil." Hence even those having grace cannot avoid sin.

2. Even those having grace must say the Lord's Prayer. Now in that prayer the petition is made that man may persevere without sin, according to the interpretation of Cyprian, as Augustine reports. A person having grace therefore cannot of himself avoid mortal sin.

3. Perseverance is a gift of the Holy Spirit. But it is not within the power even of a person having grace to have the gifts of the Holy Spirit. Since abstaining from mortal sin up to the end of one's life belongs to perseverance, it therefore seems that even a person having grace cannot avoid mortal sin.

4. The defect of sin is related to the existence deriving from grace as nothingness is related to natural existence. But a creature, which has obtained natural existence from God, cannot keep itself in natural existence without falling into nothingness unless it is conserved by the hand of its Creator. Consequently, a person who has obtained grace likewise cannot of himself keep from falling into mortal sin.

To the Contrary:

1'. In the second Epistle to the Corinthians (12:9) it is written: "My grace is sufficient for thee." Now it would not suffice if mortal sin could not be avoided by its means. A man can therefore avoid mortal sin by means of grace.

2'. This is seen from the words of the Master: "After reparation before a man is confirmed in good he is pressed by concupiscence, but he is not conquered. He has, to be sure, weakness in regard to evil, but grace in regard to good. As a result he is able to sin because of his freedom and weakness, and he is able not to sin mortally because of his freedom and helping grace."

REPLY:

It is one thing to say that someone can abstain from sin and another to say that he can persevere until the end of his life in abstaining from sin. When it is said that someone can abstain from sin, emphasis is placed only upon the negation, as meaning that someone is able not to sin. And, when there is question of mortal sin, anyone in the state of grace is able to do this, because there is no habitual inclination to sin in one who has grace. Rather there is in him a habitual inclination to avoid sin. As soon as anything is presented to him under the aspect of mortal sin, therefore, because of his habitual inclination he refuses it consent, unless he makes an effort to the contrary, following his concupiscence. But there is no necessity of following it, even though he cannot avoid having some movement of concupiscence arise entirely preceding the act of free choice. Because, then, he cannot help having such movements, he is not able to avoid all venial sins. But because in him no movement of free choice precedes full deliberation, drawing him to sin as by the inclination of a habit, he is therefore able to avoid all mortal sins.

But when it is said that he can persevere in abstaining from sin up to the end of his life, the emphasis is placed upon something affirmative, meaning that a person places himself in a state such that sin cannot be in him; for in no other way could a man make himself persevere by the act of his free choice than by making himself impeccable. This, however, does not fall within the power of free choice, because the motive and executive power does not extend to this. Consequently, a man cannot be the cause of his own perseverance, but is under the necessity of begging for perseverance from God.

Answers to Difficulties:

1. The Apostle prayed that they do no evil in view of the fact that they could not succeed in persevering in abstinence from evil except with divine help.

2. The same is to be said in answer to this.

3. Perseverance is spoken of in two senses: (1) Sometimes it is a special virtue; and so it is a habit whose act is to have the determination to persevere unshakably. In this sense everyone who has grace has perseverance, even though he is in fact not going to persevere until the end. (2) Perseverance is taken as a particular circumstance of virtue designating the permanence of virtue up to the end of life. In this sense perseverance is not in the power of one who has grace.

4. When we speak of nature we do not exclude the things by which nature is kept in existence. In the same way, when we speak of grace we do not exclude the operation of God conserving grace in existence. Without God's operation a person is not able to continue either in natural existence or in the existence deriving from grace.