Both Stephen R. Donaldson and P. D. Ouspensky are known for esotericism?
P. D. Ouspensky Pyotr Demianovich Ouspenskii (known in English as Peter D. Ouspensky, Пётр Демья́нович Успе́нский; 5 March 1878 – 2 October 1947), was a Russian mathematician and esotericist known for his expositions of the early work of the Greek-Armenian teacher of esoteric doctrine George Gurdjieff, whom he met in Moscow in 1915. He was associated with the ideas and practices originating with Gurdjieff from then on. He shared the (Gurdjieff) "system" for 25 years in England and the United States, having separated from Gurdjieff in 1924 personally, for reasons he explains in the last chapter of his book "In Search of the Miraculous".
List of occult terms The occult (from the Latin word "occultus" "clandestine, hidden, secret") is "knowledge of the hidden". In common English usage, "occult" refers to "knowledge of the paranormal", as opposed to "knowledge of the measurable", usually referred to as science. The term is sometimes taken to mean knowledge that "is meant only for certain people" or that "must be kept hidden", but for most practicing occultists it is simply the study of a deeper spiritual reality that extends beyond pure reason and the physical sciences. The terms "esoteric" and "arcane" can also be used to describe the occult, in addition to their meanings unrelated to the supernatural.