What, my friends, do we think love is if not fire? And what is sin if not rust? Hence it is said that 'many sins are forgiven her because she has loved much' (Lk. 7:47). This means she has completely burned away the rust of sin because she is mightily aflame with the fire of love. The more the heart of a sinner is consumed by the fire of love, the more fully is the rust of sin consumed.
St. Gregory the Great