Theologicae regulae

He alone is truly omnipotent who can do all things which "to be able" is to be able to do something.

This belongs to God alone: for he alone can do all that "to be able" is to be able to do something. Whence, although he cannot sin, this does not derogate from his omnipotence, since to be able to sin is rather a mark of impotence than of power: for it is from weakness. But could not Adam sin before sin? Yet he did not have weakness. To which it is said, that weakness is understood in two ways, as privation and as negation; when it is understood as privation, it denotes vice, and weakness removes a habit: in this way Adam was weak after sin; when it is conceived as negation, vice is not implied, but only the habit of firmness is removed: in this way Adam was weak before sin, not because he had vice, or any weakness, but because he did not have firmness. God, however, is neither weak by any vice, in that he has some impotence, nor because he has weakness. But is it to be granted that he can run, or walk? No: because power and bodily exercise are implied, which it is wicked to understand concerning God: yet he is not for this reason less omnipotent, because although he does not exercise such actions, yet his power is subject to them, and he does them by authority, not by action.