Augustine of Hippo

And what is here more fitly understood than that very desire of good of which we are speaking? For good begins then to be longed for when it has begun to grow sweet. But when good is done by fear of penalty, not by the love of righteousness, good is not yet well done. Nor is that done in the heart that seems to be done in the act, when a person would rather not do it if he could evade it with impunity. Therefore the "blessing of sweetness" is God's grace, by which is caused in us that what he prescribes to us delights us, and we desire it—that is, we love it; in which if God does not precede us, not only is it not perfected but it is not even begun, from us. For if without him we are able to do nothing, we are able neither to begin nor to perfect, because to begin, it is said, "His mercy shall prevent me"; to finish, it is said, "His mercy shall follow me."