But on the part of the power the will cannot be moved at all save by God. For the operation of the will is a certain inclination of the willer to the thing willed. And He alone can change this inclination, Who bestowed on the creature the power to will: just as that agent alone can change the natural inclination, which can give the power to which follows that natural inclination. Now God alone gave to the creature the power to will, because He alone is the author of the intellectual nature. Therefore an angel cannot move another angel's will.
Reply Obj. 1: Cleansing and perfecting are to be understood according to the mode of enlightenment. And since God enlightens by changing the intellect and will, He cleanses by removing defects of intellect and will, and perfects unto the end of the intellect and will. But the enlightenment caused by an angel concerns the intellect, as explained above (A. 1); therefore an angel is to be understood as cleansing from the defect of nescience in the intellect; and as perfecting unto the consummate end of the intellect, and this is the knowledge of truth. Thus Dionysius says (Eccl. Hier. vi): that "in the heavenly hierarchy the chastening of the inferior essence is an enlightening of things unknown, that leads them to more perfect knowledge." For instance, we might say that corporeal sight is cleansed by the removal of darkness; enlightened by the diffusion of light; and perfected by being brought to the perception of the colored object.
Reply Obj. 2: One angel can induce another to love God by persuasion as explained above.
Reply Obj. 3: The Philosopher speaks of the lower sensitive appetite which can be moved by the superior intellectual appetite, because it belongs to the same nature of the soul, and because the inferior appetite is a power in a corporeal organ. But this does not apply to the angels. _______________________
THIRD ARTICLE [I, Q. 106, Art. 3]
Whether an Inferior Angel Can Enlighten a Superior Angel?
Objection 1: It would seem that an inferior angel can enlighten a superior angel. For the ecclesiastical hierarchy is derived from, and represents the heavenly hierarchy; and hence the heavenly Jerusalem is called "our mother" (Gal. 4:26). But in the Church even superiors are enlightened and taught by their inferiors, as the Apostle says (1 Cor. 14:31): "You may all prophesy one by one, that all may learn and all may be exhorted." Therefore, likewise in the heavenly hierarchy, the superiors can be enlightened by inferiors.
Obj. 2: Further, as the order of corporeal substances depends on the will of God, so also does the order of spiritual substances. But, as was said above (Q. 105, A. 6), God sometimes acts outside the order of corporeal substances. Therefore He also sometimes acts outside the order of spiritual substances, by enlightening inferior otherwise than through their superiors. Therefore in that way the inferiors enlightened by God can enlighten superiors.
Obj. 3: Further, one angel enlightens the other to whom he turns, as was above explained (A. 1). But since this turning to another is voluntary, the highest angel can turn to the lowest passing over the others. Therefore he can enlighten him immediately; and thus the latter can enlighten his superiors.
On the contrary, Dionysius says that "this is the Divine unalterable law, that inferior things are led to God by the superior" (Coel. Hier. iv; Eccl. Hier. v).