“I do not, however, use this method with all patients. It is an error to state, as some specialists do, that from their formula there can be no deviation; because, as no two minds are constituted alike, so they cannot be affected alike. While one will yield by intense will exerted through my eyes, another may, by the same means, become fretful, timid, nervous, and more wakeful than he was before. The same rule applies to gesture, tones of the voice, and mesmeric passes. That which has a soothing and lulling effect on one, may have an opposite effect on another. There can be no unvarying rule applicable to all patients. The means must be left to the judgment of the operator, who by a long course of psychological training should be able to judge what measures are necessary to obtain control of his subject. Just as in drugs, one person may take a dose without injury that will kill another, so in hypnosis, one person can be put into a deep sleep by means that would be totally ineffectual in another, and even then the mental states differ in each individual—that which in one induces a gentle slumber may plunge his neighbor into a deep cataleptic state.” That hypnotism may be produced by purely physical or mechanical means seems to have been demonstrated by an incident which started Doctor Burq, a Frenchman, upon a scientific inquiry which lasted many years. “While practising as a young doctor, he had one day been obliged to go out and had deemed it advisable to lock up a patient in his absence. Just as he was leaving the house he heard the sound as of a body suddenly falling. He hurried back into the room and found his patient in a state of catalepsy. Monsieur Burq was at that time studying magnetism, and he at once sought for the cause of this phenomenon. He noticed that the door-handle was of copper. The next day he wrapped a glove around the handle, again shut the patient in, and this time nothing occurred. He interrogated the patient, but she could give him no explanation. He then tried the effect of copper on all the subjects at the Salpetriere and the Cochin hospitals, and found that a great number were affected by it.” At the Charity hospital in Paris, Doctor Luys used an apparatus moved by clockwork. Doctor Foveau, one of his pupils, thus describes it: