If, however, the spectator is once convinced that he has evidence of the supernatural, he soon sees it in every accident and incident of the performance. Not only that he overlooks natural physical explanations, but he is led to create marvels by the very ardor of his sincerity. At a materializing séance the believer recognizes a dear friend in a carelessly arranged drapery seen in a dim light. Conclusive evidence of the subjective character of such perceptions is furnished by the fact that the same appearance is frequently recognized by different sitters as the spiritual counterpart of entirely different and totally dissimilar persons. A "spirit-photograph" is declared to be the precise image of entirely unlike individuals. In the "Revelations of a Spirit Medium," we read that a wire gauze mask placed in front of a handkerchief, made luminous by phosphorus, and projected through the opening of the cabinet, was "recognized by dozens of persons as fathers, mothers, sisters, brothers, cousins, sweethearts, wives, husbands, and various other relatives and friends." Each one sees what he expects to see, what appeals to his interests the most intensely. What the unprejudiced observer recognizes as the flimsily disguised form of the medium, the believer transforms into the object of his thoughts and longings. Only let the form be vague enough, the light dim enough, the emotions upon a sufficient strain, and that part of perception in which the external image is deficient will be readily supplied by the subjective tendencies of each individual. In the presence of such a mental attitude the possibilities of deception are endless; the performer grows bolder as his victim passes from a watchful, critical attitude to one of easy conviction, and we get scientific proofs of the fourth dimension of space, of the possibility of matter passing through matter, of the levitation or elongation of the medium's body, of the transcendence of the laws of gravity. And the same performance that convinced Professor Zoellner of the reality of the fourth dimension of space would prove to the spiritualist the intercourse with deceased friends, would convince the theosophist of the flight of the performer's astral body; and, it may not be irrelevant to add, it was the same type of performance that served and yet serves to terrify the minds of uncultivated and superstitious savages. All depends not upon what is done, but upon the mental disposition of the spectator. Little by little, through neglect, through mal-observation and lapses of memory, through an unwillingness to mistrust the reports of an excited consciousness, caution is abandoned and credulity enters. Mediums are actually seen flying out of one window and in through another. The wildest and most far-fetched fantastic explanation is preferred above a simple one; the bounds of the normal are passed; real hallucinations set in; conduct becomes irrational, and a state hardly distinguishable from insanity ensues.