The elemental forces evoked by this ceremony may be compared to gunpowder. Any fool can blow himself up with powder by setting a match to it, but it takes a skilled artillerist to harness the forces and make them propel a projectile to a given target. Experiment with elemental forces is analogous and the greater part of the ritual deals with the protection of the operator or sorcerer himself from those dread spirits who obey his summons. In 1912 I attended the course of lectures on psychic science given at a sub-school of the University of Jena. A fellow-student there gave me a letter of introduction to Gottlieb Bentlemeyer, a professor of law at one of the Hanover Hochschulen and an ardent student of black magic. At that time he had rooms in the Wiesenstrasse and had in his charge one or two private pupils whom he was cramming for their necessary examinations. One of these lads, a youngster from Stettin, in North Prussia, was his assistant in the necromantic art, and was a most highly gifted sensitive or hypnotic subject. It was not until we had had several ordinary séances and he had shown me some astounding experiments in the externalization of sensibility and clairvoyance under hypnosis that I deemed it fit to mention the subject of necromancy. We were at that time in the Hanover Museum and had been examining an exhibit of “Qualapparat”--racks, winches, and torturing-irons of various descriptions. It was our discussion of the possible sending of the spirit of his assistant, Walther Kraus, under hypnosis to psychometrize these vile memorials of a brutal past that raised the subject. We came to the conclusion that the experiment would be extremely hazardous, but Bentlemeyer kindly offered to attempt to call up the spirit of one or more of the men who had used these things. “It will not be an easy task to find them,” he said, “but being men of blood it may be possible to find them by means of the blood elementals.” It took us three days to make our preparations, for although Bentlemeyer had an excellent and systematically arranged cabinet of magical requisites, one or two things had to be procured. His association with the Hochschule enabled him to obtain fresh blood through the agency of one of his medical colleagues. We rehearsed the ritual carefully, in order that there should be no fault, and I must confess that I prepared myself for the ordeal with considerable trepidation. His ceremonial of evocation was slightly at variance with accepted French practice, but the discrepancies were not material and appeared to have crept in during the time of King Frederick Wilhelm of Prussia. Bentlemeyer informed me that the original MS. in German and Hebrew had been in the possession of the celebrated Steinert.[29] It was a clear autumn night with a perfect moon; the air had a touch of frost in it and the great town of Hanover was quiet and still.