one comes to sin by three steps—suggestion, pleasure, consent—so there are three varieties of sin itself: in the heart, in the act, in the habit
St. Augustine, St. Augustine: The Lord’s Sermon on the Mount, ed. Johannes Quasten and Joseph C. Plumpe, trans. John J. Jepson, vol. 5, Ancient Christian Writers (New York; Mahwah, NJ: Paulist Press, 1948), 45.