C.S. Lewis's Ransom Trilogy sprang, on the personal level, from a conversation and a coincidence. The conversation was with his friend Tolkien, and though Lewis has left no record of it, Tolkien mentions it no fewer than five times in his published Letters, with convincing consistency. According to Tolkien, what happened was that Lewis said to him, 'If they won't write the kind of books we want to read, we shall have to write them ourselves.' They agreed accordingly 'each to write an excursionary “Thriller” . . . discovering Myth', one about space travel and one about travel in time, and the toss of a coin gave time to Tolkien and space to Lewis. The results of the agreement were very different. Lewis had finished his first 'excursionary thriller', Out of the Silent Planet, by November 1937, when he submitted it to J.M. Dent and it was rejected. Tolkien then stepped in and used his influence with the publisher Stanley Unwin, who had by this time accepted The Hobbit, to reconsider his friend's work, which duly appeared in 1938, with its two sequels in 1943 and 1945. Lewis attempted to repay the favour by working 'plugs' for Tolkien's projected time-thriller into the postscript to Out of the Silent Planet and the preface to That Hideous Strength, but Tolkien's efforts to fulfil their agreement only appeared many years later and unfinished, as 'The Lost Road' and 'The Notion Club Papers' in volumes 5 and 9 of the twelve-volume History of Middle-earth edited by Christopher Tolkien.