The philologist and author J. R. R. Tolkien explored time travel in his fiction in a variety of ways. The passage of time in The Lord of the Rings is uneven, seeming to run at differing speeds in the realms of Men and of Elves. In this, Tolkien was following medieval tradition in which time proceeds differently in Elfland. The whole work, too, following the theory he spelt out in his essay "On Fairy-Stories", is meant to transport the reader into another time. He built a process of decline and fall in Middle-earth into the story, echoing the sense of impending destruction of Norse mythology. The Elves attempt to delay this decline as far as possible in their realms of Rivendell and Lothlórien, using their Rings of Power to slow the passage of time. Elvish time, in The Lord of the Rings as