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.