We proceed to the first article thus:
1. It seems that a man cannot merit anything from God. No one merits a reward by repaying what he owes to another. But we cannot even fully repay what we owe to God, by all the good that we do. For we always owe him more than this, as the philosopher says in 8 Ethics 14. Hence it is said in Luke 17:10: "when ye shall have done all those things which are commanded you, say, We are unprofitable servants: we have done that which was our duty to do." It follows that a man cannot merit anything from God.
2. Again, it seems that a man merits nothing from God if he profits himself, but profits God nothing. Now by good work a man profits himself or another man, but not God. For it is said in Job 35:7: "If thou be righteous, what givest thou him? Or what receiveth he of thine hand?" It follows that a man cannot merit anything from God.
3. Again, whoever merits anything from another makes that other his debtor, since he who owes a reward ought to render it to him who merits it. But God is a debtor to no one, wherefore it is said in Rom.11:35: "Or who hath first given to him, and it shall be recompensed unto him again?" It follows that no one can merit anything from God.
On the other hand: it is said in Jer.31:16: "thy work shall be rewarded." Now a reward means something given for merit. Hence it seems that a man can merit something from God.
I answer: merit and reward mean the same thing. We call it a reward when it is given to someone in return for his work or labour, as a price for it. Now to give a reward for work or labour is an act of justice, just as to give a fair price for something received from another is an act of justice, and justice, as the philosopher says in 5 Ethics 4, is a kind of equality. Justice obtains absolutely between those between whom equality obtains absolutely. It does not obtain absolutely between those between whom equality does not obtain absolutely, but there may nevertheless be a kind of justice between them, since we speak of the "right" of a father, or of a master, as the philosopher says in ch.6 of the same book. Merit and reward have accordingly an absolute meaning where justice obtains absolutely. But in so far as the meaning of justice remains where justice obtains relatively and not absolutely, the meaning of merit is relative though not absolute, such as is applicable to a son who deserves something from his father, or to a slave who deserves something from his master.
Now there is obviously a very great inequality between God and man. The gulf betwixt them is indeed infinite. Moreover, all the good that is in a man is due to God. The kind of justice which obtains where there is absolute equality cannot therefore obtain between man and God. There obtains only the justice which is relative to the proportion of what is wrought by each, according to their own mode. But since both the mode and the manner of man's virtue are due to God, it is only by a previous divine ordination that a man can merit anything from God. That is, a man can receive as a reward from God only what God has given him the power to work for by his own effort; just as natural things attain, by their own movements and activities, that to which they are divinely ordained. There is this difference, however. A rational creature moves itself to its action by its free will, and its action is therefore meritorious. This is not the case with other creatures.
On the first point: a man has merit in so far as he does what he ought by his own will. The act of justice whereby one repays a debt would not otherwise be meritorious.
On the second point: God does not seek to gain anything from our good works. He seeks to be glorified by them, i.e., that his goodness should be shown forth. He seeks this by his own works also. Neither does anything accrue to God from our worship of him, but to ourselves. Hence we merit something from God not because our works profit him, but because we work to his glory.
On the third point: our own action is meritorious only by reason of a previous divine ordination. It does not follow, therefore, that God becomes a debtor to ourselves simply. Rather does he become a debtor to himself, in so far as it is right that what he has ordained should be fulfilled.