There are two reasons why we sin: either we do not see what ought to be done or we do not do what we now know must be done. The first of these causes is ignorance; the second is weakness. We must fight against them but to conquer them we need divine aid—the grace to see what should be done and the grace to make our delight in doing it stronger than our delight in those things which make us sin knowingly with our eyes wide open.
—Augustine, Enchiridion on Faith, Hope, and Charity, 22.81
I don’t know about you, but this is a terrible struggle, even with God’s help. Of course, it is impossible without the Spirit’s help and Presence.