J.R.R. Tolkien was the author and C.S. Lewis friend who helped inspire the fictional language in Lewis's space stories. Tolkien’s expertise in philology and historical languages influenced Lewis’s treatment of language and invented cultures.
Lewis and Tolkien met at Oxford and became close members of the Inklings, an informal literary discussion group. They read drafts aloud, criticized one another’s work, and encouraged each other’s fiction. Tolkien was developing The Lord of the Rings while Lewis was writing works such as the Space Trilogy and The Chronicles of Narnia.
Lewis’s protagonist in Out of the Silent Planet is Elwin Ransom, a philologist whose knowledge of languages is crucial to the story. The novel includes several invented languages and societies, making linguistic discovery part of the plot rather than mere decoration.
Charles Williams and Owen Barfield were also important Inklings, so they can be confused with Tolkien in questions about Lewis’s literary circle. Tolkien, however, was the fellow philologist and fantasy author most closely associated with Lewis.