Thomas Aquinas — on Rom 11:35 (Commentary on Romans)

“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).”