Lewis and Tolkien shared a love of Norse mythology, and Lewis read the first early drafts of what would become Tolkien’s Lord of the Rings trilogy. Tolkien later said he owed his friend “an unpayable debt” for convincing him the “stuff” could be more than merely a “private hobby.” Tolkien, in turn, was the one who convinced Lewis—an atheist in his youth—to convert to Christianity.

At which point, Lewis became an Anglican, which was absolutely not what the devoutly Catholic Tolkien was expecting. He wasn’t pleased either.