Chapter 19 — Part II: The Sacraments — Penance
Section 55. With propriety, therefore, is contrition defined a sorrow, because it produces sorrow; hence penitents, in order to express it, used to change their garments. Our Lord alludes to this custom when He says: Woe to thee, Corozain, woe to thee, Bethsaida: for if in Tyre and Sidon had been wrought the miracles that have been wrought in you, they had long ago done penance in sack-cloth and ashes.