P.D. Ouspensky (1878–1947)
Peter D. Ouspensky was a Russian occultist, esoteric teacher and author known primary for his work in regard to the Gurdjieff system also known as the “fourth way”. His second book “Tertium Organum”, published in 1912 and his fourth “A New Model of the Universe” in 1931 are considered his most important works with "Tertium Organum" still held in high regard in some circles.
In 1916 his two part study of evolution, human nature and the relationship between humans the spritural world “Talks with a Devil” was published. The book was first released in Russian and then in English with a introduction and editing by J. G. Bennett. I stumbled upon “Talks with a Devil” around 2002 and it made a huge impression on me and continues to affect my work and ideas today.