Spiritism (German: Der Spiritismus) is an 1885 book by German philosopher Eduard von Hartmann, the author of the famous treatise Philosophy of the Unconscious. In professor Corinna Treitel's opinion, publication of this book became one of the "key events" in history of the "German occult movement." This book was "one of the first works to attempt a complete psychological explanation of all occult phenomena." According to Charles Massey, one of the founders of the Society for Psychical Research, publication of this book made the "most brutal blow" out of all ones that were ever directed against Spiritualism. Source: Wikipedia (en)