Did anyone know that C.S Lewis author of The Chronicles of Narnia and Tolkien of Lord of the Rings were really good friends??
If two young professors had not met at an otherwise ordinary Oxford faculty meeting in 1926, those wondrous lands would still be unknown to us. If it hadn't been for the friendship between Tolkien and Lewis, the world would likely never have seen The Narnia Chronicles, The Lord of the Rings, and much else!!
Personally, they had both read and enjoyed such stories as they were growing up, in collections by the brothers Grimm, Andrew Lang, and others. Lewis had also heard Celtic myths—his nurse had told him some of the folk tales of Ireland.
Professionally, they studied and taught the literatures of medieval romance and, in Tolkien's case, the background of Norse myth. And they realized that it was only quite recently that such stories had become marginalized as "children's stories." Through much of history these were tales told and enjoyed by grown-ups. Even strong warriors enjoyed them, rejoicing in their triumphant moments, weeping at tragic turns of events. These stories told them important things about life—about who they were and what the world was like, and about the realm of the divine.
It dawned on both men that there was a need to create a readership again for these books—especially an adult readership. Lewis's space trilogy came out of this same impulse to write the sort of stories that he and Tolkien liked to read. He felt he could say things in science fiction that he couldn't say in other ways. And Tolkien had been expressing this sense already for years when the two men met—ever since World War One he had been writing hundreds of pages of a cycle of myth and legend from the early ages of Middle-earth. This, it would later turn out, would provide the "pre-history" for The Lord of the Rings, some of which was published after his death in The Silmarillion.
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Not to be rude - but who doesn't know? It's very well-documented in just about everything concerned with either Lewis or Tolkien.
As for their relationship and their influences on one another....well, Lewis' "Narnia" can be blamed upon the meddling of....oh, I can't remember his name, but he was a (somewhat) mutual friend of the two who converted Lewis back to Christianity....as for Lewis' influence on Tolkien, well, it certainly existed, but I don't think it was necessarily major....
BTW: I'd say that Tolkien wrote his mythologies primarily for his enjoyment, and due to his original need to provide a coherent mythological framework for Britain, (specifically, the English portion).