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." It will be noted that in cases analogous to those I have just cited, contagion, after having been at work among the popular classes, has spread to the higher classes of society. This is what we see happening at the present day with regard to the socialist doctrines which are beginning to be held by those who will yet be their first victims. Contagion is so powerful a force that even the sentiment of personal interest disappears under its action. This is the explanation of the fact that every opinion adopted by the populace always ends in implanting itself with great vigour in the highest social strata, however obvious be the absurdity of the triumphant opinion. This reaction of the lower upon the higher social classes is the more curious, owing to the circumstance that the beliefs of the crowd always have their origin to a greater or less extent in some higher idea, which has often remained without influence in the sphere in which it was evolved. Leaders and agitators, subjugated by this higher idea, take hold of it, distort it and create a sect which distorts it afresh, and then propagates it amongst the masses, who carry the process of deformation still further. Become a popular truth the idea returns, as it were, to its source and exerts an influence on the upper classes of a nation. In the long run it is intelligence that shapes the destiny of the world, but very indirectly. The philosophers who evolve ideas have long since returned to dust, when, as the result of the process I have just described, the fruit of their reflection ends by triumphing. 3. PRESTIGE Great power is given to ideas propagated by affirmation, repetition, and contagion by the circumstance that they acquire in time that mysterious force known as prestige.