This very fact that crowds possess in common ordinary qualities explains why they can never accomplish acts demanding a high degree of intelligence. The decisions affecting matters of general interest come to by an assembly of men of distinction, but specialists in different walks of life, are not sensibly superior to the decisions that would be adopted by a gathering of imbeciles. The truth is, they can only bring to bear in common on the work in hand those mediocre qualities which are the birthright of every average individual. In crowds it is stupidity and not mother-wit that is accumulated. It is not all the world, as is so often repeated, that has more wit than Voltaire, but assuredly Voltaire that has more wit than all the world, if by "all the world" crowds are to be understood. If the individuals of a crowd confined themselves to putting in common the ordinary qualities of which each of them has his share, there would merely result the striking of an average, and not, as we have said is actually the case, the creation of new characteristics. How is it that these new characteristics are created? This is what we are now to investigate. Different causes determine the appearance of these characteristics peculiar to crowds, and not possessed by isolated individuals. The first is that the individual forming part of a crowd acquires, solely from numerical considerations, a sentiment of invincible power which allows him to yield to instincts which, had he been alone, he would perforce have kept under restraint. He will be the less disposed to check himself from the consideration that, a crowd being anonymous, and in consequence irresponsible, the sentiment of responsibility which always controls individuals disappears entirely. The second cause, which is contagion, also intervenes to determine the manifestation in crowds of their special characteristics, and at the same time the trend they are to take. Contagion is a phenomenon of which it is easy to establish the presence, but that it is not easy to explain. It must be classed among those phenomena of a hypnotic order, which we shall shortly study. In a crowd every sentiment and act is contagious, and contagious to such a degree that an individual readily sacrifices his personal interest to the collective interest. This is an aptitude very contrary to his nature, and of which a man is scarcely capable, except when he makes part of a crowd. A third cause, and by far the most important, determines in the individuals of a crowd special characteristics which are quite contrary at times to those presented by the isolated individual. I allude to that suggestibility of which, moreover, the contagion mentioned above is neither more nor less than an effect.