Summa contra Gentiles1.81 Chapter LXXXI. That God does not necessarily will other things than himself

Now if God wills the divine goodness and being necessarily, someone might think that He wills other things necessarily also: since He wills all else by willing His own goodness, as we have already proved. Yet to those who look at it aright it is clear that He wills other things not of necessity. For He wills other things as ordered to the end which is His goodness. Now the will is not necessarily directed to the means, if the end is possible without them: for the physician, supposing him to have the will to heal, has no need to prescribe to the patient those remedies without which He can heal the patient. Since, then, God's goodness can be without other things, nay more, since nothing accrues thereto from other things, He is under no necessity to will other things through willing His own goodness.

Again. Since the good understood is the proper object of the will, any concept of the intellect, provided it retains an aspect of goodness, can be an object of the will. Wherefore, although the being of a thing as such is good, and its not-being an evil, the not-being of a thing can be an object of the will by reason of some connected good which is retained, albeit not of necessity: because it is good for a thing to be, even though another be non-existent. Hence that good alone is the will, according to its nature, unable to will not to be, without the existence of which, the aspect of good is wholly done away. Now such a good is God alone. Wherefore the will, according to its nature, is able to will the not-being of anything whatever except God. Now will is in God according to its full capacity, since all things in Him are in every way perfect. Hence God can will the not-being of anything whatever except Himself. Therefore He does not necessarily will things other than Himself.

Moreover. God, by willing His own goodness, wills other things to be, in as much as they partake of His goodness. Now, since God's goodness is infinite, it can be participated in an infinite number of ways, and in other ways besides those in which it is participated by those creatures which now are. If, then, through willing His own goodness, He willed of necessity the things which participate it, it would follow that He wills an infinite number of creatures partaking of His goodness in an infinite number of ways. But this is clearly false: for if He willed it, they would exist, since His will is the source of being to things, as we shall prove further on. Therefore He does not necessarily will those things also that are not.

Again. A wise man, through willing the cause, wills the effect which follows necessarily from the cause: for it would be foolish to will that the sun exist above the earth, and that there be no brightness of day. On the contrary, it is not necessary for one through willing the cause to will an effect which does not follow of necessity from the cause. Now other things proceed from God not necessarily, as we shall show further on. Therefore it is not necessary that God will other things through willing Himself.

Moreover. Things proceed from God as products of art from a craftsman, as we shall show further on. Now the craftsman, though he will himself to have his art, does not necessarily will to produce his work. Therefore neither does God necessarily will things other than Himself.

We must accordingly consider why it is that God knows of necessity other things than Himself, whereas He wills them not of necessity; and yet through understanding and willing Himself, He understands and wills other things. The reason is this. Because that the person who understands, understands something, is due to the understanding person being conditioned in a certain way, in so far as a thing is actually understood through its likeness being in the person who understands it. Whereas that the wilier wills something, is due to the thing willed being conditioned in some way: since we will a thing either because it is an end, or because it is directed to an end. Now the divine perfection necessarily requires that all things should be in God, in order that they may be understood in Him: whereas the divine goodness does not necessarily demand that the other things which are directed to it as their end should exist. For this reason it is necessary that God should know, but not will, other things. Wherefore neither does He will all things that can possibly be directed to His goodness: although He knows all that can in any way be directed to His essence, whereby He understands.