Apart from the deliberate imposture, due more often than we suspect to the megalomaniac impulses referred to above, there is some ground for believing in the existence of a still more subtle form of apparent fraud. It is frequently asserted by mediums of repute that they are unable to do justice to themselves or exercise their gifts to good purpose because of the unsatisfactory influence of one or more sitters of an aggressively sceptical type, a curious parallel――be it said in all reverence――to the strange remark of the Evangelist that the miracles of Our Lord were sometimes actually prevented by the disbelief of His hearers. But may the disbelieving sitters, in some instances, go further than a mere hindrance of genuine phenomena and actually cause the production of trickery and fraud on the part of the medium? Given a medium susceptible to telepathic suggestion, and one or more sitters suspecting or convinced in advance that all they will witness at the _séance_ will be an exhibition of trickery, it is easy to see that telepathic suggestion of fraud, conscious or unconscious, from the minds of these sceptics may result in trickery which is primarily due not to the medium but to themselves. This risk is obviously accentuated when the medium falls (as, for example, in Mrs Piper’s case) into a cataleptic condition or some form of ordinary hypnosis. In any case it is confidently asserted by psychical researchers of capacity and experience that the same medium may be fraudulent at one moment and genuine at another. Such a thesis is doubtless hard of acceptance to ordinary men or women, however disposed they may be to an unprejudiced consideration of psychic phenomena; and it was, in fact, rejected by the original founders of the Psychical Research Society, who definitely refused to include within the area of their investigations the alleged phenomena of any medium once detected in the perpetration of fraud. Further experience, however, has apparently modified this once inflexible attitude, and at any rate a majority of the Council of the S. P. R. are now willing to hold experimental _séances_ with mediums against whom fraud has been openly alleged or actually proved. The writer shares the view of this majority, for, as far as he can judge from personal experience or the definite testimony of others, a medium like Eusapia Palladino was, sometimes, indubitably guilty of patent and childish trickery (which she would subsequently admit quite shamelessly), and at other times produced valid phenomena of amazing interest under the strictest test-conditions.