Contagion is so powerful that it forces upon individuals not only certain opinions, but certain modes of feeling as well. Contagion is the cause of the contempt in which, at a given period, certain works are held—the example of "Tannhauser" may be cited—which, a few years later, for the same reason are admired by those who were foremost in criticising them.
The opinions and beliefs of crowds are specially propagated by contagion, but never by reasoning. The conceptions at present rife among the working classes have been acquired at the public-house as the result of affirmation, repetition, and contagion, and indeed the mode of creation of the beliefs of crowds of every age has scarcely been different. Renan justly institutes a comparison between the first founders of Christianity and "the socialist working men spreading their ideas from public-house to public-house"; while Voltaire had already observed in connection with the Christian religion that "for more than a hundred years it was only embraced by the vilest riff-raff."