The "Canopus in Argos" novels present an advanced interstellar society's efforts to accelerate the evolution of other worlds, including Earth. Using Sufi concepts, to which Lessing had been introduced in the mid-1960s by her "good friend and teacher" Idries Shah, the series of novels also uses an approach similar to that employed by the early 20th century mystic G. I. Gurdjieff in his work "All and Everything". Earlier works of "inner space" fiction like "Briefing for a Descent into Hell" (1971) and "Memoirs of a Survivor" (1974) also connect to this theme. Lessing's interest had turned to Sufism after coming to the realisation that Marxism ignored spiritual matters, leaving her disillusioned.