We proceed to the fifth article thus:
1. It seems that the foreknowledge of merits is the cause of predestination. For the apostle says: "whom he did foreknow, he also did predestinate" (Rom.8:29), and the gloss of Ambrose on the words "I will have mercy on whom I will have mercy" (Rom.9:15) says: "I will have mercy on whom I foreknow will return to me with his whole heart." It thus appears that the foreknowledge of merits is the cause of predestination.
2. Again, divine predestination includes the divine will. Now the divine will cannot be irrational, since Augustine says that predestination is "the decision to have mercy" (2 De Praed. Sanct.17). But there is no rational ground for predestination except foreknowledge of merits. Foreknowledge of merits is therefore the cause, or rational ground, of predestination.
3. Again, it is said in Rom.9:14: "Is there unrighteousness  with God? God forbid." Now it would be unrighteous to give unequal things to those who are equal, and all men are equal in nature, and also in original sin. It is in the merits and demerits of their actions that they differ. It is therefore only because he foreknows their unequal merits that God prepares for men such unequal things as predestination and rejection.
On the other hand: the apostle says (Titus 3:5): "Not by works of righteousness which we have done, but according to his mercy he saved us." Now God predestines us to salvation in the same way as he saves us. It follows that the foreknowledge of merits is not the cause or ground of predestination.
I answer: we said in the preceding article that predestination involves will. We must therefore look for the reason for predestination in the same way as we looked for a reason for the divine will. Now we said in Q.19, Art.5, that we cannot assign any cause for the divine act of will, although it is possible to find a reason why things are willed, in so far as God wills one thing for the sake of another. No one has been so foolish as to say that merits are the cause of the divine act by which God predestines. The question is as to whether there is a reason for the effects of predestination, that is, whether God has preordained that he will give the effects of predestination to anyone on account of merits.
Some have said that the effect of predestination is ordained for us beforehand, on account of merits already earned in a previous life. This was the view of Origen. He thought that the souls of men were created first, and that according to their works they were assigned different states on becoming united with bodies in this world. But the apostle rules out such a view by what he says in Rom.9:11-12: "For the children being not yet born, neither having done any good or evil . . . not of works, but of him that calleth. It was said unto her, The elder shall serve the younger."
Others have said that merits already earned in this life are the ground and cause of the effects of predestination. The Pelagians, for example, held that the beginning of well-doing lies with ourselves, although its consummation lies with God; and that this explains why the effect of predestination is given to one and not to another, since one has made a beginning by preparing himself, while another has not. But this is contrary to what the apostle says in II Cor.3:5: "Not that we are sufficient of ourselves to think anything as of ourselves." For we cannot point to any beginning which is previous to thinking, and consequently cannot say that there is anything within us which could be the reason for the effect of predestination.
Others again have said that the reason for predestination is to be found in the merits which result from the effects of it. By this they mean that God bestows grace on someone, and also preordains that he will bestow it, because he foreknows that such a one will make good use of it, just as a king gives a horse to a soldier because he knows that he will use it well. But they appear to have drawn a distinction between the results of grace and the results of free will, as if the same thing could not be the result of both. It is obvious, however, that anything which is due to grace is also the effect of predestination, and cannot be the reason for predestination, since it is included in it. And if anything else about ourselves is to be the reason for predestination, it must not be part of the effect of it. But again, anything which is due to free will is no more distinct from the effect of predestination than the result of a secondary cause is distinct from the result of a primary cause. Providence produces its effects through the operation of secondary causes, as we said in Q.19, Art.5, and even what is due to free will is the effect of predestination.
We must observe that the effect of predestination may be considered in two ways. If we are thinking of its particular effects, there is no reason why one effect of predestination should not be the ground and cause of another, nor any reason why a later effect should not be the final cause of an earlier effect. Nor is there any reason why an earlier effect of predestination should not be the cause of a later effect through its merit, which properly means its material disposition. We should then say that God has preordained that he will bestow glory on account of merits, and that he will give grace in order that glory may be merited. But if we are thinking of the effect of predestination as a whole, it is impossible that its entire, universal effect should have any cause which lies within ourselves, because anything within a man which ordains him to salvation is wholly included in the effect of predestination. Even his very preparation for grace is included in the effect of predestination, since even this is impossible without divine help, according to Lam.5:21: "Turn thou us unto thee, O Lord, and we shall be turned." The reason for the effect of predestination is therefore the divine goodness. The whole effect of predestination is ordained for the sake of the divine goodness as its end, and proceeds from the divine goodness as its prime mover.
On the first point: as we have said above, it is only as a final cause that foreknowledge of the use which will be made of grace is the ground of its bestowal.
On the second point: the rational ground for" the whole effect of predestination is the divine goodness itself. But one particular effect may still be the cause of another, as we have said.
On the third point: the reason why some are predestined and others rejected is to be found in the goodness of God. God is said to do all things for the sake of his goodness, in order that his goodness may be reflected in things. Now the divine goodness itself is single and simple. But created things cannot attain to the simple nature of the divine, and must therefore reflect the divine goodness by means of many forms. The universe thus requires diverse grades of things for the sake of its completeness, some things holding an exalted place in it and others a lowly place. In order to preserve this variety of grades, moreover, God permits some evils to arise, lest many good things should be prevented. We explained this in Q.22, Art.2, and Augustine agrees with it (1 Ad Simplician 11; 2 De Bono Persev.).  Now we may consider the whole race of men in the same light as the whole universe of things. God has willed to show forth his goodness in men by mercifully sparing some of them, whom he predestines, and by justly punishing others, whom he rejects. This is the reason why he chooses some and rejects others, and it is the reason given by the apostle in Rom.9:22: "What if God, willing to show his wrath [that is, to vindicate his justice], and to make his power known, endured [that is, permitted] with much longsuffering the vessels of wrath fitted to destruction: and that he might make known the riches of his glory on the vessels of mercy, which he hath afore prepared unto glory," and also in II Tim.2:20: "But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour." There is indeed no reason why some are elected to glory while others are rejected, except the will of God. Augustine says accordingly (Tract.26 in Joan.): "If thou wouldst not err, seek not to judge why God draws one man and not another." In the realm of nature, also, we can see a reason why one part of primary matter should be made originally in the form of fire, and another part of it in the form of earth. This was necessary for the diversity of species in natural things, since primary matter in itself is wholly uniform. But why one particular part of primary matter should be under one form, and another particular part of it under another form, depends entirely on the will of God; just as it depends entirely on the will of a builder whether one individual stone shall be in one part of a wall and another in another part of it, even though his art supplies the reason why some stones should be in the one part and some in the other. But there is no injustice in God's preparation of unequal things for those who are not unequal. There would indeed be injustice if the effects of predestination were rendered as a debt which is due, and not given by grace. But when something is given gratuitously, one may give more or less of it to whomsoever it may please one's will, without injustice, provided that one does not withhold what is due. This is what the master of the house is saying in Matt.20:14-15: "Take that thine is, and go thy way. . . . Is it not lawful for me to do what I will with mine own?"
 Migne: "non est iniquitas apud Deum."  Cf. De Corrept. et Grat., 8, 17.
 Cf. De Corrept. et Grat., 8, 17.