Whether a Man can Merit Eternal Life, without Grace
We proceed to the fifth article thus:
1. It seems that a man can merit eternal life without grace. Our Lord says (Matt.19:17): |if thou wilt enter into life, keep the commandments| -- whence it appears that whether a man enters into eternal life depends on his own will. Now we can do by ourselves what depends on our own will. It seems, therefore, that a man can merit eternal life by himself.
2. Again, God gives eternal life to men as a meed or reward, according to Matt.5:12: |great is your reward in heaven,| and Ps.62:12 says that a meed or reward is rendered by God according to a man's works: |thou renderest to every man according to his work.| Hence the attainment of eternal life seems to depend on a man's own power, since a man has control of his own works.
3. Again, eternal life is the ultimate end of human life. Now every natural thing can attain its end by its natural power. Much more then can man, who is of a higher nature, attain eternal life by his natural power, without any grace.
On the other hand: the apostle says: |the gift of God is eternal life| (Rom.6:23), and the gloss by Augustine says: |this means that God leads us to eternal life for his mercy's sake| (De Grat. et Lib. Arb.9).
I answer: actions which lead to an end must be commensurate with the end. But no action transcends the limits of the principle by which a thing acts. Thus we see that no natural thing can produce, by its own action, an effect which is greater than its own active power, but only an effect commensurate with this power. Now eternal life is an end which exceeds what is commensurate with human nature, as is clear from what we said in Q.5, Art.5. It follows that a man cannot, by his natural powers, produce meritorious works commensurate with eternal life. A higher power is needed for this, namely, the power of grace. Hence a man cannot merit eternal life without grace, although he can perform works which lead to such good as is connatural to him, such as labour in the field, eat, drink, have friends, and so on, as is said by Augustine (or by another, in Contra Pelagianos 3; Hypognosticon 3, cap.4).
On the first point: a man performs works deserving of eternal life by his own will. But as Augustine says in the same passage, his will must be prepared by God through grace.
On the second point: if one is to fulfil the commandments of the law in the adequate way which is meritorious, grace is indispensable. This agrees with what Augustine's gloss says on Rom.6:23, |the gift of God is eternal life,| namely that |it is certain that eternal life is the reward for good works, but works so rewarded are the result of God's grace| (De Grat. et Lib. Arb.8). It also agrees with what we said in the preceding article.
On the third point: this objection argues from the end which is connatural to man. But the very fact that human nature is nobler than natural things means that it can be raised, at least through the help of grace, to an end higher than this, to which inferior natures can nowise attain. A man who can recover his health through the help of medicine is, similarly, nearer to health than another who can in nowise do so, as the philosopher remarks in 2 De Coelo, texts 64, 65.