CHAPTER LXXXVIII—That other Subsistent Intelligences cannot be direct Causes of our Elections and Volitions⁶⁶⁸⁶⁶⁸   In Chapp. LXXXII-LXXXVII St Thomas argues that the heavenly bodies, which he says are “perfect without blending of contraries, being neither light nor heavy, nor hot nor cold,” are the instruments whereby God prompts and controls all movement and change in material bodies on earth: that nevertheless they exercise no direct action upon the human understanding, which is something nobler than they, as the incorporeal is nobler than the incorporeal: nor are they arbiters of human will and conduct, except remotely and by occasion, as they affect the human body, under which affection the will makes its free choice: nor do they even determine the course of other terrestrial events absolutely, since much depends upon the condition and capacities of terrestrial physical causes.
   Repeatedly in this work St Thomas shows his grievous misgivings as to the later Platonic position, that stars are animals and heavenly spheres have souls. He considered that the stars and their containing spheres, if they were not themselves animate, were moved by angels, which is another thing. Cf. Plato Rep. X, 616 C, sq.

NOR is it to be thought that the souls of the heavens, if any such souls there be, or any other separately subsisting created intelligences, can directly thrust a volition in upon us, or be the cause of our choice. For the actions of all creatures are contained in the order of divine providence, and cannot act contrary to the conditions of action which providence has laid down.⁶⁶⁹⁶⁶⁹Thus even in sinning the will cannot but fix upon some apparent aspect of good (Chap. X). Now it is a law of providence that everything be immediately induced to action by its own proximate cause. But the proximate cause of volition is good apprehended by the understanding: that is the proper object of the will, and the will is moved by it as sight by colour. No subsistent creature therefore can move the will except through the medium of good grasped by the understanding. That is done by showing it that something is good to 250do, which is called persuasion. No subsistent creature therefore can act upon our will, or be the cause of our choice, otherwise than by means of persuasion.

4. “The violent is that the origin whereof is from without, without the subject of violence in any way contributing thereto.”⁶⁷⁰⁶⁷⁰Aristotle, Nic. Eth. III, i. Were then the will to be moved by any exterior principle, that motion would be violent. I call that an exterior principle of motion, which moves as an efficient cause, and not as a final cause. But violence is inconsistent with voluntariness. It is impossible therefore for the will to be moved to voluntary action by an exterior principle acting as an efficient cause, but every motion of the will must proceed from within. Now no subsistent creature is in touch with the interior of an intelligent soul: God alone is in such close connexion with the soul, as He alone is cause of its being and maintains it in existence. Therefore by God alone can a motion of the will be efficiently caused.

Hence it is said: The king’s heart is in the hand of the Lord: he shall turn it whithersoever he will (Prov. xxi, 1); and, God it is worketh in us both to will and to accomplish according to his good pleasure (Phil. ii, 13).