It will appear that much of the conflict which the present tale unfolds is the conflict between the rational investigation of intelligible facts and the unwarranted attempts at an explanation of alleged miracles,--a phase of the conflict between science and mysticism. The imperfectly understood is apt to be explained by the still more obscure; totally imaginary forms of energy are called upon to account for poorly observed effects; and so the mystery deepens, superstition spreads, and charlatanism finds a fertile field for its display. This conflict in the present instance is by no means confined to the past; the mystical and the miraculous, or at least the unintelligible side of hypnotic phenomena still finds its exponents. Accounts of observations and experiments purporting to demonstrate that hypnotism not only presents hyperæsthesia and exaggerated forms of mental activity, but transcends all normal psychological processes and reveals a hidden world in which other forces and other modes of mental communication freely appear, are widely circulated and sometimes with the authority of names of repute. But the more discerning, the more exact, and the more logical students of hypnotism, cannot accept such observations, and have often been able to point out the unmistakable sources of error which gave rise to them. The shrewdness of hypnotized subjects, the unconscious suggestion of the operator, looseness of observation and theoretical bias, exercise the same influence for error to-day as they presented in the antecedents of hypnotism.