Spiritism () 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. Contents of the book The general state of the question. The physical phenomena. The ideality of the manifestations. Transfigurations and materialisations. The spirit hypothesis. Spiritism and Spiritualism At the beginning of the first chapter Hartmann explains that "the word 'Spiritism' is of French production", but the English and most part of the Germans prefer the term "Spiritualism." The author presents to use the term "Spiritualism" to denote the metaphysical point of view, which is the opposite of materialism, and the explanation of mediumistic phenomena through participation of "spirits", he offers to call by the term "Spiritism." He believes that most people, who are aspiring for Spiritism and read Spiritist journals, have no interest in a scientific study of the phenomena of mediumship, but instead seek "the confirmation of their belief in immortality." Hartmann considers a reopening of the huge field of phenomena, that were rejected in the Age of Enlightenment, as a great merit of the modern spiritistic movement. However, in his opinion, Spiritism threatens to become a public disaster in Germany, therefore the state should use its authority in order to interest scientists in a study of the spiritistic phenomena. He writes that the public has the complete right to know about these things, and since it is not able to formulate its own opinion, it only remains to wait for the conclusions drawn by the official representatives of science. Research methodology Hartmann writes that in order to study the "abnormal phenomena of human nature" it is necessary to appeal to persons who are endowed with an abnormal organism. It should be remembered, he continues, that just as in "experiments with an electrical friction machine", there may be failures in experiments with mediums, but this should not prevent the "investigation of abnormal phenomena." He believes that the scientific study of spiritism should be based