Below is a clip from a movie about the life of Tolkien (Lord of the Rings guy) and his friendship with CS Lewis (Narnia guy) at Oxford University, where they both met. Tolkien eventually converted Lewis, who as a young man was an avowed atheist, to Christianity.
If you are familiar with Lord of the Rings, you will see a great many inspirations derived from medieval literature. Tolkien in fact was near-fluent in Old English and medieval language, and he understood the "apophatic" nature of existence to the medieval mind.
Watch the clip of an interaction between the young Lewis and older Tolkien, where Tolkien explains to Lewis the medieval understanding of nature and ontology:
It's interesting how this portrays the two authors. It's almost as if the roles are reversed where Tolkien is the idealistic youth with his head in the clouds and dreams of grandeur while Lewis is depicted as being stuck in his ways curmudgeon. Tolkien's opinions show quite well in his works especially when he speaks to myth and the idea that they're arbitrary works of fiction. He uses the idea that myths build up our world in Lord of the Ring and its part of what makes the universe he created so vast almost proving his point of their importance in the world and the archetype of one story being the source for all else.
Great observation! Indeed, Tolkien is insistent that "myth" is NOT synonymous with "Lie" or "false" or even simply "fiction", but rather it is a kind of truth, a different way of telling the truth.