First published in 1886, this comprehensive analysis of nineteenth-century spiritual experiments questions our long tradition of encounters with the supernatural, and why it appeared to have declined in influence in the writer's era. Maudsley (1835–1918), a medical psychologist and pioneer psychiatrist, sets out to bring such alleged spiritual phenomena under scientific investigation. Emphasising the natural defects and errors of human observation and reasoning, as well as the prolific activity of the imagination, this inquiry into the causes of belief in the supernatural suggests that much of it can be explained though hallucination, mania, and delusion. The book is divided into three parts: the first section concentrates on the causes of fallacies in the sound mind, while the second considers unsound mental action. The focus of part three is theopneusticism, or the attainment of supernatural knowledge by divine inspiration. This second edition appeared in 1887.