Obj. 3: Further, movement is attributed to the mover rather than to the one moved; wherefore homicide is not ascribed to the stone, but to the thrower. Therefore, if God moves the will, it follows that voluntary actions are not imputed to man for reward or blame. But this is false. Therefore God does not move the will.
On the contrary, It is written (Phil. 2:13): "It is God who worketh in us [Vulgate—'you'] both to will and to accomplish."
I answer that, As the intellect is moved by the object and by the Giver of the power of intelligence, as stated above (A. 3), so is the will moved by its object, which is good, and by Him who creates the power of willing. Now the will can be moved by good as its object, but by God alone sufficiently and efficaciously. For nothing can move a movable thing sufficiently unless the active power of the mover surpasses or at least equals the potentiality of the thing movable. Now the potentiality of the will extends to the universal good; for its object is the universal good; just as the object of the intellect is the universal being. But every created good is some particular good; God alone is the universal good. Whereas He alone fills the capacity of the will, and moves it sufficiently as its object. In like manner the power of willing is caused by God alone. For to will is nothing but to be inclined towards the object of the will, which is universal good. But to incline towards the universal good belongs to the First Mover, to Whom the ultimate end is proportionate; just as in human affairs to him that presides over the community belongs the directing of his subjects to the common weal. Wherefore in both ways it belongs to God to move the will; but especially in the second way by an interior inclination of the will.
Reply Obj. 1: A thing moved by another is forced if moved against its natural inclination; but if it is moved by another giving to it the proper natural inclination, it is not forced; as when a heavy body is made to move downwards by that which produced it, then it is not forced. In like manner God, while moving the will, does not force it, because He gives the will its own natural inclination.
Reply Obj. 2: To be moved voluntarily, is to be moved from within, that is, by an interior principle: yet this interior principle may be caused by an exterior principle; and so to be moved from within is not repugnant to being moved by another.
Reply Obj. 3: If the will were so moved by another as in no way to be moved from within itself, the act of the will would not be imputed for reward or blame. But since its being moved by another does not prevent its being moved from within itself, as we have stated (ad 2), it does not thereby forfeit the motive for merit or demerit. _______________________
FIFTH ARTICLE [I, Q. 105, Art. 5]
Whether God Works in Every Agent?
Objection 1: It would seem that God does not work in every agent. For we must not attribute any insufficiency to God. If therefore God works in every agent, He works sufficiently in each one. Hence it would be superfluous for the created agent to work at all.
Obj. 2: Further, the same work cannot proceed at the same time from two sources; as neither can one and the same movement belong to two movable things. Therefore if the creature's operation is from God operating in the creature, it cannot at the same time proceed from the creature; and so no creature works at all.