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.
To understand this phenomenon it is necessary to bear in mind certain recent physiological discoveries. We know to-day that by various processes an individual may be brought into such a condition that, having entirely lost his conscious personality, he obeys all the suggestions of the operator who has deprived him of it, and commits acts in utter contradiction with his character and habits. The most careful observations seem to prove that an individual immerged for some length of time in a crowd in action soon finds himself—either in consequence of the magnetic influence given out by the crowd, or from some other cause of which we are ignorant—in a