Men's lives are as thoroughly blended with each other as the air they breathe: evil spreads as necessarily as disease.

George Eliot (1819-1880)

The quotation is, apparently, from "Adam Bede" (1859) although it is said to reflect Eliot's strong-felt view at the heart of her later novel "Felix Holt, the Radical" (1866).

As it stands for examination the quotation seems to imply that evil has a permanence determined by the very interaction among humans: thus it corrupts, as it spreads like disease.
This allows for the notion that evil is not inherently what we are born with, sometime we did not carry the germ. But, sooner or later we will get it necessarily.

Looking at the paragraph where the quotation comes from, http://www.goodreads.com/quotes/tag/george-eliot, we may get a slightly different sense where punishment is concerned:
"“There is no sort of wrong deed of which a man can bear the punishment alone: you can't isolate yourself, and say that the evil which is in you shall not spread. Men's lives are as thoroughly blended with each other as the air they breathe: evil spreads as necessarily as disease." (There is further context as the paragraph goes on.)