Manly P. Hall was a Canadian author, lecturer, astrologer, and mystic. Spanning his seventy-year career he gave thousands of lectures, including two at Carnegie Hall, and published more than 150 volumes. Hall became an influential figure during the metaphysical movement that swept the United States in the early 1900s. His book The Secret Teachings of All Ages challenged assumptions about society's spiritual roots which made readers view them in new and diverse ways. Hall died in 1990.