During my teenage years, Led Zeppelin was nerd armor. No matter how geeky you were, you knew that Robert Plant and Jimmy Page were probably just as big a pair of geeks as you were, because their music was laced with Tolkien references. While you were reading your piles of fantasy books, there was no better music to put on than Led Zeppelin, because they were right there next to you, writing and singing songs about Gollum, ringwraiths, hobbits, and faerie women.
This song, for example, is very (very, very) loosely influenced by the ideas contained in a 1915 poem by Tolkien titled Over Old Hills and Far Away, about an encounter the narrator had with some elves dancing in the moonlight, with just a little hint of influence from The Hobbit thrown in for good measure. When I say "loosely influenced" I most emphatically mean loosely. There aren't any lyrics that map from the poem or the book to the song, and the themes are really only tangentially related. But the song captures the tone and atmosphere of Tolkien so very well that none of that matters. The song sounds like a Tolkien story put into musical form, and that's what makes it so very good.
Led Zeppelin Musical Monday Home