Anti-pelagian Writings by St. Augustine
Chapter 4.--Pelagius' System of Faculties.
In his system, he posits and distinguishes three faculties, by which he says God's commandments are fulfilled, -- capacity, volition, and action: meaning by |capacity,| that by which a man is able to be righteous; by |volition| that by which he wills to be righteous; by |action,| that by which he actually is righteous. The first of these, the capacity, he allows to have been bestowed on us by the Creator of our nature; it is not in our power, and we possess it even against our will. The other two, however, the volition and the action, he asserts to be our own; and he assigns them to us so strictly as to contend that they proceed simply from ourselves. In short, according to his view, God's grace has nothing to do with assisting those two faculties which he will have to be altogether our own, the volition and the action, but that only which is not in our own power and comes to us from God, namely the capacity; as if the faculties which are our own, that is, the volition and the action, have such avail for declining evil and doing good, that they require no divine help, whereas that faculty which we have of God, that is to say, the capacity, is so weak, that it is always assisted by the aid of grace.