The latter half of the eighteenth century seems to have offered social, intellectual, and political conditions peculiarly favorable to the success of fantastic schemers, of propagandists of strange philosophies, and advertisers of supernatural procedures for short-circuiting the road to health, wealth, knowledge, and immortality. In this period there appeared Swedenborg's inspired revelations and philosophic cult; Cagliostro's extravagant claims of personal power and bold-faced impostures; Schrepfer, who combined with Masonic mysteries a striking anticipation of the materializing séances of modern spiritualism; Gassner, the priest, exorcist, and healer; and finally Mesmer, the founder of animal magnetism, and through it the parent of an endless progeny of unproved and unprovable systems, and of equally irrational practices.
It is worth while to consider for a moment the career of Gassner, if for no other reason than that Mesmer witnessed Gassner's procedures, and that their methods have some points in common,--in particular the calling out of acute symptoms, or "a crisis," as a means of cure. Johann Joseph Gassner, a Suabian priest, appeared as a curer of disease about 1773; he regarded most maladies as of Satanic origin, and attempted cures by driving out the demon of disease by appeal to divine agency. After inquiry regarding the nature of the complaint and its symptoms, he would urge the patient to have faith, and perhaps would offer a prayer for his recovery; he would then call out the various symptoms of pain, stiffness, weakness, and the like, and at the word "_Cesset_" these symptoms would disappear. "_Cesset ista Debilitas_,"--the patient becomes as strong and as active as though he had never been sick. "_Modo adsit Febris tantum in Manu et Brachio dextro_,"--the right hand becomes cold and numb, and trembles, the pulse in this arm is rapid, feverish, and strong, but slow and normal in the left. "_Cesset in ista Manu et adeat sinistram_,"--the left arm now becomes as the right had been, and the pulse of the right is now normal; and so the treatment proceeds, accompanied by the invocation, "_Præcipio hoc in nomine Jesu_." This process of alternation of pain and its remission is continued, until at length the patient is dismissed as cured. The status of Gassner's cures, except for their more pronounced religious character, is much the same as those of Greatrakes; both exhibit the effects of suggestion, but neither recognized the process of suggestion, nor gives evidence of having produced an abnormal condition. This, however, is by no means excluded; and Greatrakes's account of the insensibility of his own arm, as well as the similar state induced in his patients by Gassner, indicate a high degree of suggestibility.