For example, I suggest to a man that his forehead itches. As soon as he feels it he is surprised, being unable to understand how my prophecy has been transformed into real itching. He then believes in my power over his nervous system, _i.e._, that his brain becomes more receptive to my words, and offers less resistance after having proved the value of my predictions. It matters little whether these are directed toward sensations or movements, or vaso-motor actions causing blushing and blanching, or suppression or bringing on of menstruation (in the case of a woman), etc. My influence over him by suggestion will increase; _i.e._, his brain will accustom itself to the suggestions which I give it by letting them dissociate its activity. This tendency to be influenced by suggestion is very contagious by example. When A influences B successfully, and C, D, E, F and G are witnesses of the fact, they will be much more easily influenced by A in the same direction; and so on. This explains suggestion affecting the masses. It is quite indifferent whether the subjective sentiment of sleep occurs more or less in the state of hypnosis or suggestion. This sentiment depends chiefly on the presence or absence of a variable degree of amnesia (want of memory to awaken). But amnesia only depends on the rupture, often fortuitous and unimportant, of the chain of remembrances in the series of super-conscious or attentional states of cerebral activity. In somnambulists, who are the most suggestible people, we can produce or suppress amnesia at will by a single word, and make them forget or remember what has passed. I must dwell on this point, because of the current dogma which assumes an essential difference between hypnotism and suggestion in the waking state. Such an assumption is based on false conception of the psychology of suggestion. The only difference consists in the suggestion of amnesia, or the subjective sentiment of sleep; or, if one prefers it, the subjective remembrance of sleep opposed to the remembrance of having been awakened. But these two remembrances may be voluntarily connected with the same past state of the brain. By _auto-suggestion_ is meant the suggestive action of spontaneous ideas--that is to say, ideas which are not suggested to the subject by any other person, but the effect of which is identical to that of external suggestions. An idea, a sentiment, dominates the mind, overcomes all its antagonists and produces a strong suggestive effect on the whole nervous system in the direction which it symbolizes. The idea of being unable to sleep often produces insomnia; the idea of sexual impotence may at once inhibit erection and render coitus impossible. The idea of yawning makes one yawn; that of coitus provokes erections; the idea of shame causes blushing; that of fear blanching; that of pity weeping.