You can’t get from whatever will be, will be, to the inefficacy of human action.
1 We should also keep in mind the fact that, just as the immutability of providence does not impose necessity on things that are foreseen, so also it does not suppress the value of prayer. For prayer is not established for the purpose of changing the eternal disposition of providence, since this is impossible, but so that a person may obtain from God the object which he desires.
Notes Recall that foreseen does not mean caused (without freedom).
2 Indeed, it is appropriate for God to consent to the holy desires of a rational creature, not in the sense that our desires may move the immutable God, but that He, in His goodness, takes steps to accomplish these desired effects in a fitting way. For, since all things naturally desire the good, as we proved above, and since it pertains to the supereminence of divine goodness to assign being, and well-being, to all in accord with a definite order, the result is that, in accord with His goodness, He fulfills the holy desires which are brought to completion by means of prayer.
3 Again, it is proper for a mover to bring the object that is moved to its end; hence, a thing is moved toward its end, and attains its end, and finds rest in it, by means of the same nature. Now, every desire is a certain movement toward the good, and indeed it cannot be present in things unless it be from God, Who is good essentially and the source of goodness. In fact, every mover moves toward something like itself. So, it is proper for God, in accord with His goodness, to bring to a fitting conclusion the proper desires that are expressed by our prayers.
4 Besides, the nearer certain things are to the mover, the more efficaciously do they follow the influence of the mover; for instance, things that are nearer to a fire become hotter from it. Now, intellectual substances are nearer to God than are inanimate natural substances. Therefore, the influence of divine motion is more efficacious on intellectual substances than on other natural substances.
But natural bodies participate in divine motion to the extent that they receive from Him a natural appetite for the good, and even in the appetite for fulfillment which is realized when they attain their appropriate ends. Therefore, there is much more reason for intellectual substances attaining the fulfillment of their desires which are presented to God by prayer.
Notes Pray for wisdom first.
5 Moreover, it pertains to the essential meaning of friendship for the lover to will the fulfillment of the desire of the beloved, because he wishes the good and the perfect for the beloved. This is the reason for the statement that “it is characteristic of friends that they will the same thing.”
Now, we showed above that God loves His creature, and the more that any one of them participates in His goodness which is the first and chief object of His love, the more does He love it. So, He wills the desires of a rational creature to be satisfied, for, compared to other creatures, it participates most perfectly in divine providence. But His will is perfective in regard to things; indeed, He is the cause of things through His will, as we showed above. Therefore, it is appropriate to divine providence for Him to fulfill the desires of a rational creature when they are presented to Him through prayer.
6 Furthermore, a creature’s good is transmitted by the divine goodness in accord with a certain likeness. But this characteristic seems most approvable among men: that they should not refuse consent to those who ask for favors in a just manner. Because of this, men are called liberal, clement, merciful, and upright. Therefore, this characteristic, of granting upright prayers, especially belongs to divine goodness.
7 Hence, it is said in the Psalm (144:19): “He will do the will of those who fear Him, and He will hear their prayers and save them”; and again the Lord says: “Everyone who asks receives, and he who seeks finds, and to him who knocks it shall be opened” (Mat. 7:8).