Chapter 37 — Part IV: Prayer — The Third Petition: Thy Will Be Done on Earth as It Is in Heaven
Section 13. The moment the first man forfeited original justice, which enabled him to bridle the passions, reason was no longer able to restrain them within the bounds of duty, or to repress those inordinate desires which are repugnant to reason. This is why the Apostle tells us that sin, that is to say, the incentive to sin, dwells in the flesh, thus giving us to understand that it does not make a mere temporary stay within us as a passing guest, but that as long as we live it maintains its abode in our members as a permanent inhabitant of the body.