Chapter 19 — Part II: The Sacraments — Penance
Section 48. Necessity Of These Integral Parts — The reason why these are the integral parts may be thus explained. Sins against God are committed by thought, by word and by deed. It is, then, but reasonable, that in recurring to the power of the keys we should endeavour to appease God's wrath, and obtain pardon for our sins by means of the very same things which we employed to offend His sovereignty.