Roman Catechism 19.50

Chapter 19 — Part II: The Sacraments — Penance

Section 50. Contrition — As the faithful require instruction on the nature and efficacy of the parts of Penance, we must begin with contrition. This subject demands careful explanation; for as often as we call to mind our past transgressions, or offend God anew, so often should our hearts be pierced with contrition.