12 And with respect to right deeds, any one may see that this happens; for as when the bad are punished others become better, so whenever the good achieve any thing right, many are urged onward to a similar zeal: a thing which has also taken place with respect to the avoiding of oaths. For many persons, observing that others had laid aside the evil practice of oaths, took a pattern from their diligence, and got the better of the sin; wherefore we are the more disposed to touch again on the subject of this admonition.
For let no one tell me that “many” have accomplished this; this is not what is desired, but that “all” should do so; and until I see this I cannot take breath. That Shepherd had a hundred sheep, and yet when one of them had wandered away, he took no account of the safety of the ninety and nine, until he found the one that was lost, and restored it again to the flock. Do you see not that this also happens with respect to the body; for if by striking against any obstacle, we have only turned back a nail, the whole body sympathizes with the member.
Say not this; that only a certain few have failed; but consider this point, that these few being unreformed, will corrupt many others. Although there was but one who had committed fornication among the Corinthians, yet Paul so groaned as if the whole city were lost. And very reasonably, for he knew that if that member were not chastened, the disease progressing onward would at length attack all the rest. I saw, but lately, in the court of justice, those distinguished men bound and conducted through the forum; and while some were wondering at this extraordinary degradation, others said there was nothing to wonder at; for that, where there is matter of treason, rank must go for nothing. Is it not then much more true that rank must be of no avail where is impiety?
Source: Homilies on the Statues (New Advent)