That God in willing Himself wills also other things besides Himself*

EVERY one desires the perfection of that which for its own sake he wills and loves: for the things which we love for their own sakes we wish to be excellent, and ever better and better, and to be multiplied as much as possible. But God wills and loves His essence for its own sake. Now that essence is not augmentable and multipliable in itself (Chap. XLII), but can be multiplied only in its likeness, which is shared by many. God therefore wills the multitude of things, inasmuch as He wills and loves His own perfection.

3. Whoever loves anything in itself and for itself, wills consequently all things in which that thing is found: as he who loves sweetness in itself must love all sweet things. But God wills and loves His own being in itself and for itself; and all other being is a sort of participation by likeness of His being.

6. The will follows the understanding. But God with His understanding understands Himself in the first place, and in Himself understands all other things: therefore in like manner He wills Himself in the first place, and in willing Himself wills all other things.

This is confirmed by the authority of Holy Scripture: Thou lovest all things that are, and hatest nothing of the things that thou hast made (Wisd. xi, 2)

1.74 : That the Object of the Will of God in the first place is God Himself
1.76 : That with one and the same Act of Will God wills Himself and all other beings