Brothers, the disease must be avoided, the pestilence evaded which creates sickness out of remedies, which causes illness to result from medicine, which turns holiness into sin, which changes atonement into guilt, and which generates division out of reconciliation. Whoever flees hypocrisy conquers; whoever runs into it does not escape. Let us flee hypocrisy, let us flee it, my brothers. May ours be the fast of simplicity; may it be holy from our innocence, pure from our purity, sincere from our sincerity. May it be hidden from people, unknown to the devil, but known to God. Whoever does not hide his treasure flaunts it; virtues that are flaunted will not remain. Just as virtues desert those who flaunt them, so they work hard at shielding those who shield them. Therefore, fasting, which is the first virtue against vices, should be placed in the fortress of our heart, since so long as it presides within us, vices will not be able to disturb us from without.
Sermon 7, section 3.
[St. Peter Chrysologus, Selected Sermons, Volume 2, William Palardy, tr. Catholic University of America (Washington, DC: 2004).]