The refined belief in the miraculous embodied in Kant's practical philosophy assumed many different forms among his followers, the Neo-Kantians, approaching sometimes more and sometimes less to the conventional beliefs. Through a long series of variations, which still continue to develop, it is gradually passing into the cruder form of superstition which we find popular to-day as spiritism, and which provides the basis for what is called occultism. Kant himself, in spite of his subtle and clear critical faculty, had a decided leaning to mysticism and positive dogmatism, which showed itself especially in his later years. He thought a good deal of Swedenborg's idea of the spirit world forming a universe apart, and compared this to his _mundus intelligibilis_. Among the natural philosophers of the first half of the nineteenth century, Schelling (in his later writings), Schubert (in his _History of the Soul_ and _Observations on the Dark Side of Science_), and Perty (in his mystic anthropology) especially investigated the mysterious phenomena of mental action, and sought to connect them with the physiological functions of the brain on the one hand and supernatural spiritual agencies on the other. Modern spook-seeking has no more value than mediæval magic, cabalism, astrology, necromancy, dream-interpretation, and invocation of the devil. We must put at the same stage of superstition the spiritism and occultism we find mentioned so much in modern literature. There are always thousands of credulous folk in educated countries who are taken in by the performances of the spiritists and their media, and are ready to believe the unbelievable. Spirit-rapping, table-turning, spirit-writing, the materialization and photographing of deceased souls, find credit, not only among the uneducated masses, but even among the most cultured, and sometimes among imaginative scientists. It has been proved without avail by numbers of impartial observations and experiments that these occultist performances depend partly on conscious fraud and partly on careless self-deception. _Mundus vult decipi_--"the world wishes to be taken in"--as the old saying has it. This spiritistic fraud is particularly dangerous when it clothes itself with the mantle of science, makes use of the physiological phenomena of hypnotism, and even assumes a monistic character. Thus, for instance, one of the best-known occultist writers, Karl du Prel, has written, not only a _Philosophy of Mysticism and Studies of Scientific Subjects_, but also (1888) a _Monistic Psychology_, which is dualistic from beginning to end. In these popular writings lively imagination and brilliant presentation are combined with a most flagrant lack of critical sense and of knowledge of the elements of biology (_cf._ chapter xvi. of the _Riddle_). It seems that the hereditary bias towards mysticism and superstition is not yet eliminated even from the educated mind of our time. It is to be explained phylogenetically