This book was written by Robert Hamill Nassau, an American Presbyterian missionary, within a Christian scope and prejudice concerning West African culture and spirituality, which were typical for the 19th and early 20th century. However, despite a nowadays anachronist and disturbing perspective, the book has remained most valuable for students of the occult, especially those interested in demonology, voodoo, hoodoo and its roots, African magick and religion, witchcraft, the classes of African spirits, and of course the spiritual and magickal use of a fetish.