For the special student of hypnotism no lesson of the history of its antecedents is more practically significant than its illumination of the extent, variety, and subtlety of unconscious suggestion. If Puységur's subjects prescribe for their own ills and see without their eyes; if Pétetin's read what is placed on their stomachs; or the interposition of poor electric-conductors prevent manifestations; if one of the subjects examined by the commission of 1784 could not be deprived of speech unless the magnetizing band passed below his mouth; if one of the Salpêtrière subjects of 1829 could be cured only by immersion in the river; if Deleuze's subjects respond differently to the minute differences in manipulations, which he believed to be essential; if the subjects whom Braid examined could prove the truth of phrenology, and the mesmerist's subjects feel the magnetic fluid streaming through their systems; if within recent times paralyses are transferred from one arm to the other by the action of a magnet, or Dr. Luys's subjects show the characteristic effects of a drug when a sealed vial containing it is placed upon the subject's neck, or respond to the puppets which he has manipulated,--surely it is as obvious that some spontaneous caprice of the subject or unconscious suggestions of the operator have originated these notions, and that unconscious imitation has further contributed to their dissemination, as it is obvious that all these in part mutually contradictory phenomena cannot be true, objective facts. The significance of more recent investigations in allied fields still turns upon the factor which unconscious suggestion plays in their production. The advocates of telepathy, whether occurring under hypnotic or more normal conditions, feel confident that unconscious suggestion as well as all other sources of error have been eliminated; the skeptical critics point out overlooked and novel modes of unconscious suggestion, and draw confidence from the history of the past, both of the unwarranted flight to improbable hypothesis on the basis of an alleged absence of a natural explanation, and of the solvent power which future investigation may hold in store.
The story of the conquest of a realm of fable by a campaign of enlightenment is always a tale of interest. The opening of a new vista directs one's gaze outward over unexplored areas. It may be, as our seventeenth-century chronicler tells us, that "we are all Indians and Salvages in what we have not accustomed our senses," and that, "what was Conjuring in the last age is Mathematiques in this"; but our more extensive acquaintance with the course of discovery and the demonstration of truth has given us a more logical sense of the probable and the improbable; and the evolution by which conjuring becomes mathematics is more intimately understood. The recent establishment of hypnotism in its scientific aspects furnishes the proper perspective for the comprehension of its antecedents; it gives confidence that its future development will incorporate the spirit of present research, as it will avoid the aberrations of the past; and it gives to the story of its vicissitudes a timely pertinence as well as a psychological significance.