In it, he gives a highly critical view of much of the popular literature on the topic. In his words, these books describe Hitler and the Nazis as being controlled by a "hidden power . . . characterized either as a discarnate entity (e.g., 'black forces', 'invisible hierarchies', 'unknown superiors') or as a magical elite in a remote age or distant location".[4] He referred to the writers of this genre as "crypto-historians".[4] The works of the genre, he wrote,