Summa contra Gentiles2.6 Chapter VI. That it becomes God to be the source of being to other things

Taking then as granted the things that were proved in the foregoing Book, let us now proceed to prove that it becomes God to be the source and cause of being to other things.

For it was shown above by the proof of Aristotle that there is a first efficient cause which we call God. Now an efficient cause brings its effects into being. Therefore God is the cause of being to other things.

Again. It was shown in the First Book by the argument of the same author, that there is a first immovable mover, which we call God. Now the first mover in any order of movements is the cause of all the movements in that order. Since then many things are brought into being by the movements of the heaven, and since God has been proved to be the first mover in the order of those movements, it follows that God is the cause of being to many things.

Moreover. That which belongs to a thing by its nature, must needs be in that thing universally; as for man to be rational, and for fire to tend upwards. Now it belongs to a being in act that it should enact an effect; for every agent acts according as it is in act. Therefore it is natural to every being in act to enact something existing in act. Now God is being in act, as we proved in the First Book. Therefore it is competent to Him to produce something in act, to which He is the cause of being.

Further. It is a sign of perfection in things of the lower world, that they are able to produce their like, as stated by the Philosopher (4 Meteor.). Now God is supremely perfect, as was proved in the First Book. Therefore it is competent to Him to produce something in act like unto Himself, so that He is the cause of its being.

Again. It was shown in the First Book’ that God wills to communicate His being to other things by way of likeness. Now it belongs to the will’s perfection to be the principle of action and movement, as stated in 3 De Anima. Since then God’s will is perfect, it lacks not the power of communicating His being to a thing by way of likeness. And thus He will be the cause of its being.

Further. The more perfect the principle of a thing’s action is, to so many more and further distant things can it extend its action: thus fire, if weak, heats only that which is nigh, but, if strong, heats even distant things. Now pure act, which is God, is more perfect than act mingled with potentiality, as it is with us. But act is the principle of action. Since, then, by the act which is in us we are able to proceed not only to actions that abide in us, such as intelligence and volition, but also to actions that pass on to outward things, and through which certain things are made by us; much more can God, in that He is in act, not only understand and will, but also produce an effect. And thus He can be the cause of being to other things.

Hence it is said (Job. v. 9): Who doth great things and unsearchable... things without number.