ABSTRACT
The importance that Charcot and the School of the Salpêtrière attributed to knowledge of the different hypnotic states is well known. The increasing predominance of the adverse doctrines of the School of Nancy singularly weakened it in the opinion of the contemporaneous medical world, it is true; but it may be asked whether this knowledge, duly proved and generalized, does not remain, after all, one of the guiding principles to which all those who are endeavoring to place the study of parapsychic phenomena in the field of positive science must necessarily have recourse.
