Summa contra Gentiles1.76 Chapter LXXVI. That God, by the one act of his will, wills himself and other things

This being proved, it follows that God, by one act of His will, wills Himself and other things.

For every power tends by one operation or act to its object and the formal aspect of that object: even as by the one sight, we see light and colour made visible by light. Now when we will something solely for the sake of an end, that which is desired for the sake of the end takes its aspect of thing willed from the end; and thus the end is compared to it as the formal aspect to an object, as light to colour. Since, then, God wills all things for His own sake as for the sake of an end, as we have proved, He wills Himself and other things by one act of His will.

Moreover. That which is perfectly known and desired is known and desired with respect to its whole virtue. Now the virtue of an end consists not only in its being desired for its own sake, but also in other things being made desirable for its sake. Wherefore he that desires an end perfectly, desires it in both these ways. But it cannot be admitted that God has an act whereby He wills Himself without willing Himself perfectly, since in Him there is nothing imperfect. Hence by every act in which God wills Himself, He wills Himself absolutely, and other things for His own sake. And He wills not things other than Himself, except because He wills Himself, as was proved above. It follows therefore that not by distinct acts but by one and the same act He wills Himself and other things.

Again. As appears from what has been said, discursion in the act of the cognitive faculty occurs when we know the premisses apart from the conclusions, and draw the conclusions from them: for if we were to see the conclusions in the premisses themselves, simply through knowing the premisses, there would be no discursion, as neither is there when we see something reflected in a mirror. Now just as the premisses are related to the conclusions in speculative matters, so are the ends to the means in practical and appetitive matters: because even as we know conclusions through their premisses, so does the end lead us to the appetite and practice of the means. Accordingly if a person will the end and the means separately, there will be discursion in his will. But there can be no such thing in God, since He is outside all movement. Therefore it follows that God wills Himself and other things simultaneously by the one same act of His will.

Again. Since God always wills Himself, if He will Himself by one, and other things by another act, it follows that there are two acts of will in Him at the same time. But this is impossible: since of one simple power there are not at the one time two operations.

Further. In every act of the will the thing willed is compared to the will as mover to moved. Wherefore if there be an act of the divine will, by which He wills things other than Himself, and which is distinct from the act whereby He wills Himself, there will be in Him something else that moves the divine will: and this is impossible.

Moreover. God's willing is His being as we have proved. But in God there is only one being. Therefore in Him there is but one act of the will.

Again. It is becoming to God to will in as much as He is intelligent. Wherefore just as by one act He understands Himself and other things, in as much as His essence is the exemplar of all things, so by one act He wills Himself and other things, in as much as His goodness is the type of all goodness.