Corruption And Cleansing

Nescitis quia modicum fermentum totam massam corrumpit? Ita et peccatum unius, quod cognitum non arguitur, multos contaminat; immo omnes qui norunt, et non devitant, aut cum possint arguere, dissimulant. Non enim sibi videtur peccare, quando a nullo corripitur aut vitatur. Expurgate vetus fermentum, ut sitis nova conspersio. Hoc duplici genere accipiendum est, quia est et fermentum humana doctrina, dicente Salvatore: Cavete a fermento Pharisaeorum, id est a doctrina. Et ad malam ergo doctrinam cavendam, et ad hanc causam dictum est, quia eiecto fornicatore, vetus fermentum eiicitur. Ideo autem vetus quia antiqui erroris peccatum est. Nova autem compositio, Christi doctrina est. Ambrosiaster, In Epistolam Beati Pauli Ad Corinthios Primam, Caput V Source: Migne PL 17.209a-c

Do you not know that a little leaven corrupts the whole mass? 1 Thus even one sin, which is known and not disputed, infects many. Indeed all who know and do not admonish it or dispute it when they are able to do so, they lie. For it does not seem a sin to a man when he is not corrected nor condemned by anyone. Clean out the old leaven that you may be a new lump. This must be understood in two ways, because there is a leaven of human teaching, concerning which the Saviour says: 'Beware the leaven of the Pharisees.' 1 That is, beware their teaching, and therefore it is a warning against wicked teaching, and for this reason it was said, because with the ejection of the fornicator, the old leaven is ejected. Therefore it is old because it is the sin of the old error. But the new lump is the teaching of Christ. Ambrosiaster, Commentary On The First Letter of Saint Paul To The Corinthians, Chapter 5 1 1 Cor 5.6 2 Mt 16.11