Do not be ashamed to enter again into the Church. Be ashamed when you sin. Do not be ashamed when you repent. Pay attention to what the devil did to you. These are two things: sin and repentance. Sin is a wound; repentance is a medicine. Just as there are for the body wounds and medicines, so for the soul are sins and repentance. However, sin has the shame and repentance possesses the courage.
[St. John Chrysostom, Homily VIII, On Repentance and Almsgiving]