Romans 11:35

And in like manner also, "Or who has first given to him, and it shall be recompensed to him?" is to be understood. For no one has first bestowed anything upon his Maker: since even this very thing that he is, each one has received from his Creator.

"For who hath known the mind of the Lord? or who hath been His counsellor? Or who hath first given to Him, and it shall be recompensed unto him again?"

What he means is nearly this: that though He is so wise, yet He has not His Wisdom from any other, but is Himself the Fountain of good things. And though He hath done so great things, and made us so great presents, yet it was not by borrowing from any other that He gave them, but by making them spring forth from Himself; nor as owing any a return for having received from him, but as always being Himself the first to do the benefits; for this is a chief mark of riches, to overflow abundantly, and yet need no aid.

Who has done something beforehand, so that instead of magnifying God's mercy, he boasts that he has received what he deserved?

No good work comes from the dead; nothing righteous from the ungodly. Their whole salvation is gratuitous and is therefore the glory of God, so that he who glories may glory in him of whose glory he has stood in need.

He is also the source of all good things, and whatever He gives, He gives not as one obligated to repay, like someone who has received something from another, but out of His own goodness. For "who has first given to Him," that is, to God, that it should be repaid to him? That is, so that the benefaction bestowed by God might be considered a repayment to the one who gave?

Therefore when it condemns and reprobates, it operates according to justice: but when it predestines, according to grace and mercy, which does not exclude justice. Because therefore all, insofar as they were of the mass of perdition, deserved to be condemned: therefore more are reprobated than chosen, so that it may be shown that salvation is according to special grace, but damnation according to common justice. Therefore no one can complain about the divine will, because it does all things most rightly; indeed in all things we ought to give thanks and honor the governance of divine providence. But if anyone should ask why it bestows the gift of grace on one sinner rather than another, here it is necessary to impose silence on human loquacity and to exclaim with the Apostle: O the depth of the riches of the wisdom and knowledge of God, how incomprehensible are his judgments, and unsearchable his ways! For who has known the mind of the Lord, or who has been his counselor, or who has first given to him, and it shall be repaid to him? For from him and through him and in him are all things. To him be glory forever and ever. Amen.

Second, he shows the excellence of divine wisdom according as it has height in itself, and indeed is that height which is the supreme principle. Two points pertain to this:
first, that it does not proceed from something else;
second, that other things proceed from it, at for from him.

That God's wisdom does not depend on a higher source is shown in two ways.

First, by the fact that it is not instructed by someone else's teaching. Hence, he says: or who has been his counselor? As if to say: no one. For counsel is needed by one who does not fully know how something is to be done, and this does not apply to God: to whom have you given counsel? Perhaps to him that has no wisdom (Job 26:3). Who has stood in the counsel of the Lord? (Jer 23:18).

Second, by the fact that it is not helped by another's gift. Hence he adds: or who has first given to him, and recompense shall be made him, as one giving first? As if to say: no one. For man can give God only what he has received from God: all this abundance comes from your hand and is all your own (1 Chr 29:16); if you do justly, what shall you give him, or what shall he receive of your hand? (Job 35:7).