Ambrosiaster : Just as the sin of one person contaminates many, if it is not dealt with once it is known, so also does the sin of the many who know what is happening and either do not turn away from it or pretend that they have not noticed it. Sin does not look like sin if it is not corrected or avoided by anybody. — COMMENTARY ON PAUL'S EPISTLES Irenaeus : And we have the precept: "If any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner, with such an one no not to eat." And again does the apostle say, "Let no man deceive you with vain words; for because of these things cometh the wrath of God upon the sons of mistrust. Be not ye therefore partakers with them." And as then the condemnation of sinners extended to others who approved of them, and joined in their society; so also is it the case at present, that "a little leaven leaveneth the whole lump." And as the wrath of God did then descend upon the unrighteous, here also does the apostle likewise say: "For the wrath of God shall be revealed from heaven against all ungodliness and unrighteousness of those men who hold back the truth in unrighteousness." — Against Heresies Book 4 John Chrysostom : Then, having ended his sentence, and spoken it in brief without dwelling on it, he brings in again a rebuke, directing himself against them; "Your glorying is not good:" signifying that it was they up to the present time who had hindered him from repenting, by taking pride in him. Next he shews that he is taking this step in order to spare not that person only, but also those to whom he writes. To which effect he adds, "Know ye not, that a little leaven leaveneth the whole lump?" "For," saith he, "though the offence be his, yet if neglected it hath power to waste the rest of the body of the Church also. For when the first transgressor escapes punishment, speedily will others also commit the same faults." In these words he indicates moreover that their struggle and their danger is for the whole Church, not for any one person. For which purpose he needeth also the similitude of the leaven. For "as that," saith he, "though it be but little, transforms unto its own nature the whole lump; so also this man, if he be let go unpunished and this sin turn out unavenged, will corrupt likewise all the rest." — Homily on 1 Corinthians 15 Tertullian : Are women who think that, in furnishing to their neighbour that which is demanded of beauty, they are furnishing it to themselves also, to augment that (beauty) when (naturally) given them, and to strive after it when not (thus) given? Some one will say, "Why, then, if voluptuousness be shut out and chastity let in, may (we) not enjoy the praise of beauty alone, and glory in a bodily good? "Let whoever finds pleasure in "glorying in the flesh" see to that. — On the Apparel of Women Book II Tertullian : It remains, therefore, that his meaning was, that that spirit which is accounted to exist in the Church must be presented "saved," that is, untainted by the contagion of impurities in the day of the Lord, by the ejection of the incestuous fornicator; if, that is, he subjoins: "Know ye not, that a little leaven spoileth the savour of the whole lump? " And yet incestuous fornication was not a little, but a large, leaven. — On Modesty