This book was originally published in 1920. To reprint it now verbatim, except for an occasional correction of a misprint, calls for an explanation. The explanation is quite simple. No book published in the past forty years has replaced this one or come near replacing it. Regardless of date of publication, this one remains the best encyclopedia available. - Publisher's preface.

A generation ago it was the fashion to sneer at the occult sciences. But today, men of science in the foremost files of thought have placed them on the dissecting slab as fit subjects for careful examination. The result of their analysis during the past twenty years, if it has not permitted us to pierce the veil which divides man and the "supernatural," has, at all events, served to purge our sight sufficiently to enable us to see things on this side of it with a clearer vision, and to regard such researches with a more tolerant eye than hitherto. My attempt has been to present to the general reader a conspectus of the Occult Sciences as a whole. - Introduction.