A comfortable temperature, between 68 degrees and 78 degrees, will be found most favorable for inducing hypnosis; and, as a rule, the farther the departure from these limits the more difficult it becomes to gain control over a subject.

An expert hypnotist was invited by a body of scientific men to give a special exhibition of his powers, to illustrate his method of inducing hypnosis. He selected his best subject, and met the scientists by appointment in a suburban home, one intensely hot afternoon in July. But imagine his chagrin and the disappointment of the others, when he utterly failed to do more than render the subject drowsy. The intense heat, the short trip on the train and the unusual circumstances pertaining to the occasion, had all tended to disturb the subject's nervous equilibrium in such a manner that hypnosis could not be induced.

Such instances are rare in good subjects, but that they do occasionally occur illustrates the importance of observing all possible precautions and of taking advantage of such favorable influences as can be secured while trying to "break in" a new subject or while endeavoring to develop hypnotic power.

During a public exhibition, given by a celebrated hypnotist one cold winter night, the dozen or more subjects upon the stage all manifested pronounced signs of awakening in the midst of a most interesting performance, and the operator was obliged to make many passes over them in order to retain control. The cause of the partial awakening was a very cold draught of air blowing across the stage from a window opened by the janitor for the sake of ventilation. The operator, as soon as he realized the cause, ordered the window closed and impressively stated to his subjects, "Now, you are all warm and comfortable."

The above instance well serves to illustrate a peculiar feature of the hypnotic condition. Actual physical suffering or discomfort, such as may be caused by heat or cold, is readily, and often most acutely experienced by the hypnotized subject, unless the operator has specifically impressed upon him that he does not experience it. And, again, when the temperature is normal, the subject may be made to think that it is intensely cold or intensely hot, without control over him being lost. Suggestion can overcome the effect of the most intense suffering, and unless suggestion of ease is made, physical suffering may cause awakening from the hypnotic state.

It is especially necessary for an operator to remember these facts when subjects are under his control. Various circumstances may occur to cause unpleasant physical sensations, and these must be quickly realized and hypnotic suggestions made accordingly.