Summa contra Gentiles1.86 Chapter LXXXVI. That a reason of the divine will can be assigned

We can gather from what has been said that it is possible to assign a reason of the divine will.

For the end is the reason of willing the means. Now God wills His goodness as an end, and He wills all else as means to that end. Therefore His goodness is the reason why He wills other things which are different from Him.

Again. The particular good is directed to the good of the whole as its end, as the imperfect to the perfect. Now things are the object of the divine will according to their place in the order of good. Hence it follows that the good of the universe is the reason why God wills each particular good in the universe.

Again. As we have shown above, supposing God to will a certain thing, it follows of necessity that He wills whatever is required for that thing. Now that which imposes necessity on something else, is the reason why this other thing is. Therefore the reason why God wills that which is requisite for a thing, is that the thing for which it is requisite may be.

Accordingly we may proceed thus in assigning the reason of the divine will. God wills man to have reason that man may be; He wills man to be that the universe may be complete; and He wills the good of the universe because it is befitting His goodness.

Yet these three reasons do not indicate the same relationship. For the divine goodness neither depends on the perfection of the universe nor gains anything from it. While though the perfection of the universe depends necessarily on certain particular goods, which are the essential parts of the universe, it depends on others not of necessity, although a certain goodness or beauty accrues to the universe through them, for instance through such things as are merely for the protection or beauty of the other parts. And the particular good depends necessarily on those things which are absolutely required for it: although this also has certain things which are for its better being. Wherefore sometimes the reason of the divine will indicates only fittingness, sometimes utility, and sometimes necessity by supposition; but absolutely necessity only when God wills Himself.