Written by renowned Swiss physician and experimental psychologist Théodore Flournoy (1854–1920), this 1911 publication offers a scientific treatment of nineteenth-century spiritual interests and beliefs. Dedicating his work to the Swiss scientist and psychical researcher Marc Thury and to the American psychologist and philosopher William James, Flournoy approaches the subject of 'spiritism', or communication with the dead, with great caution, claiming that it had never been adequately proven and that such practices could most likely be explained as mental processes inherent in the mediums themselves. While recognising and offering validation of the existence of phenomena such as telekinesis, clairvoyance and telepathy, as well as the survival of the soul after death, in this book Flournoy casts doubt on the living human's ability to contact the spirits of the deceased.