The book takes influence from the works of Frank Podmore, Joseph Jastrow and Ivor Lloyd Tuckett dealing with the "fallacies underlying psychical research". Rawcliffe critically examines claims of the occult, parapsychology and spiritualism concluding that they are best explained by psychological factors such as hallucination, hysteria, neurosis and suggestion as well as "delusion, fraud, prestidigitation, and limitless credulity."[2] Rawcliffe found possible naturalistic explanations for all parapsychological experiments he investigated, noting that there is no scientific evidence for any paranormal power. He suggested that many of the results from ESP experiments can be explained by what he termed endophasic enneurosis (unsconscious whispering).[3]