Commentaria in Summam contra Gentiles, Liber II

Since it has been seen that it befits God to be the principle and cause of being for others, it is necessary to determine concerning that power by which something is brought into esse ¹. Concerning this, Saint Thomas does three things: first he shows that active power exists in God; second, he shows what it is, in the following chapter; third, how it is, in chapter x.

As to the first, the following conclusion is laid down: In God there is active power.

It is proved first (1). God is the principle of being (essendi) for others. [Therefore it belongs to Him to be powerful].

[Second. Actus belongs to God]. Therefore in him there is active potency. — The consequence is evident. For just as passive potency follows upon being in potency, so active potency follows upon being in act.

(1) The first proof is given. — The Ferrara text, as it has come down to us, omits the end of the first proof and the beginning of the second. We have supplied it from the letter of St. Thomas.

Third. Divine perfection includes in itself all perfections. Therefore, etc. — The consequence is evident. For active power pertains to the perfection of a thing.

Fourth. God is an agent and a mover. Therefore He is able to act. Therefore in Him there is active power, but not passive power. — The first consequence is proved: because from the opposite of the consequent the opposite of the antecedent is inferred. For it follows: He cannot act; therefore it is impossible that He act; therefore He is not an agent and a mover.

Note that in this final argument he added, but not passive: lest perhaps someone should think that, because active power is posited in God, passive power must also be attributed to him. He does not, however, prove here that passive power is not in God, because he showed this above distinctly and in itself.

It is finally confirmed by the authority of the Psalm.