Hysteria is common to man and animals. Amongst the numerous chimpanzees which I have owned, several have shown signs of hysteria. Some, when they were in the slightest degree annoyed, lay on the ground, screaming terribly, and rolling about like children in a fit of passion. One young chimpanzee used to pull out its hair when it was in a fit of temper. The view that hysteria is a relapse to the condition of our animal ancestors is supported by the conception of hysterical phenomena, suggested by Dr. Babinsky.[167] This well-known neurologist thinks that “the phenomena of hysteria have two special characters, the one being that they can be reproduced by suggestion in some cases with the most complete fidelity, and the other that they can disappear under the sole influence of persuasion.” M. Babinsky thinks that “the hysteric patient is neither unconscious nor completely conscious, but is in a state of special consciousness.” In my opinion the latter condition corresponds to the state of mind of our more or less remote ancestors. Occasionally a man, under some sudden impulse, falls into a condition of extreme violence, and, being unable to control himself, commits acts of which he repents immediately afterwards. It is the custom to say that at such times the brute has awakened in the man. This is more than a metaphor. (Probably some nervous mechanism from a remote ancestor has come into action, at the call of some stimulation.) As our anthropoid ancestors and primitive man lived in tribes, it is natural that when men are grouped together, certain savage instincts should awaken. In this connection it is interesting to study the psychology of crowds. When man is surrounded by a great many of his fellows, he becomes particularly responsive to suggestion. This condition is characterised as follows by M. G. Le Bon,[168] the author of a study on the psychology of crowds: “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 special state, which much resembles the state of fascination in which the hypnotised individual finds himself in the hands of the hypnotiser. The activity of the brain being paralysed in the case of the hypnotised subject, the latter becomes the slave of all the unconscious activities of his spinal cord, which the hypnotiser directs at will. The conscious personality has entirely vanished; will and discernment are lost. All feelings and thoughts are bent in the direction determined by the hypnotiser” (p. 11). Man, under the influence of the crowd, gets into a condition like that of a hysterical patient and displays a state of mind identical with that of our ancestors. “Moreover, by the mere fact that he forms part of an organised crowd, a man descends several rungs in the ladder of civilisation.