Affirmation, however, has no real influence unless it be constantly repeated, and so far as possible in the same terms. It was Napoleon, I believe, who said that there is only one figure in rhetoric of serious importance, namely, repetition. The thing affirmed comes by repetition to fix itself in the mind in such a way that it is accepted in the end as a demonstrated truth. The influence of repetition on crowds is comprehensible when the power is seen which it exercises on the most enlightened minds. This power is due to the fact that the repeated statement is embedded in the long run in those profound regions of our unconscious selves in which the motives of our actions are forged. At the end of a certain time we have forgotten who is the author of the repeated assertion, and we finish by believing it. To this circumstance is due the astonishing power of advertisements. When we have read a hundred, a thousand, times that X's chocolate is the best, we imagine we have heard it said in many quarters, and we end by acquiring the certitude that such is the fact. When we have read a thousand times that Y's flour has cured the most illustrious persons of the most obstinate maladies, we are tempted at last to try it when suffering from an illness of a similar kind. If we always read in the same papers that A is an arrant scamp and B a most honest man we finish by being convinced that this is the truth, unless, indeed, we are given to reading another paper of the contrary opinion, in which the two qualifications are reversed. Affirmation and repetition are alone powerful enough to combat each other. When an affirmation has been sufficiently repeated and there is unanimity in this repetition--as has occurred in the case of certain famous financial undertakings rich enough to purchase every assistance-- what is called a current of opinion is formed and the powerful mechanism of contagion intervenes. Ideas, sentiments, emotions, and beliefs possess in crowds a contagious power as intense as that of microbes. This phenomenon is very natural, since it is observed even in animals when they are together in number. Should a horse in a stable take to biting his manger the other horses in the stable will imitate him. A panic that has seized on a few sheep will soon extend to the whole flock. In the case of men collected in a crowd all emotions are very rapidly contagious, which explains the suddenness of panics. Brain disorders, like madness, are themselves contagious. The frequency of madness among doctors who are specialists for the mad is notorious. Indeed, forms of madness have recently been cited--agoraphobia, for instance--which are communicable from men to animals.