Gregory the Great
Catena Aurea · Lukasevangelium 15
Either what woman having ten pieces of silver, if she lose one piece, doth not light a candle, and sweep the house, and seek diligently till she find it? And when she hath found it, she calleth her friends and her neighbours together, saying, Rejoice with me; for I have found the piece which I had lost. Likewise, I say unto you, there is joy in the presence of the angels of God over one sinner that repenteth.
(in Hom. 34. ut sup.) To work repentance is to mourn over past sins, and not to commit things to be mourned over. For he who weeps over some things so as yet to commit others, still knows not how to work repentance, or is a hypocrite; he must also reflect that by so doing he satisfies not his Creator, since he who had done what was forbidden, must cut off himself even from what is lawful, and so should blame himself in the least things who remembers that he has offended in the greatest.