Themes are the fundamental and often universal ideas explored in a literary work.
Sauron bound up much of his power in the One Ring when he forged it ages ago, and whoever wields the Ring has access to some of that power. The full extent and nature of the Ring’s power never becomes entirely clear to us, but we get the sense that the Ring symbolizes a power almost without limits, and which is utterly corrupting. It is immensely difficult for many of the characters to resist the temptation to take the Ring for themselves and use it for their own ends. Regardless of the wearer’s initial intentions, good or evil, the Ring’s power always turns the wearer to evil. Indeed, even keeping the Ring is dangerous. The Fellowship of the Ring is strewn with examples of those who are corrupted by the Ring. The power of the Ring transformed the Black Riders, once human kings, into fearsome, undead Ringwraiths. Gollum, once a young boy named Sméagol, killed his friend Déagol for the Ring and then gradually became a wretched, crouching, froglike creature who thinks only of his desire to retrieve the Ring for himself. During the travels of the Fellowship, Boromir grows increasingly corrupted by the proximity of the Ring, wanting to use its power to destroy Sauron rather than destroy the Ring itself, as Elrond and Gandalf have advised; ultimately, the Ring leads Boromir to desire it for himself. For many, the great power offered by the Ring overrides all rational thought. The power of the Ring is by no means the only temptation in Middle-earth—the Dwarves of Moria, for example, coveted mithril too much, and they dug so deep that they awakened the Balrog beneath them—but the Ring is the greatest temptation and therefore the greatest threat.
The Middle-earth of The Lord of the Rings is a world on the cusp of a transformation. After the events the novel describes, the age of the Elves will pass and the age of Men will dawn. A large portion of the story eulogizes this passing age of the Elves. The Elves and their realms have a beauty and grace unmatched by anything else in Middle-earth. Though the Elves themselves are immortal, as Galadriel tells us, the destruction of Sauron’s One Ring will weaken the Three Elven Rings, forcing the Elves to leave Middle-earth and fade away. Throughout the novel, Tolkien gives us the sense that the adventures of the Ring represent the last burst of a sort of magic that will not be found in the world that comes afterward. This later world will be a world without Sauron, but also a world without Lothlórien. Even in chapters about the Hobbits and the lowly Shire, we sense that we are witnessing something good and pure that is, for whatever reason, no longer present in this world. The Hobbits, the narrator tells us, have become somewhat estranged from Men in the times since The Lord of the Rings took place, and now avoid us “with dismay.”
The sense of transience and lost grandeur that pervades The Lord of the Rings goes, in part, with the territory in which Tolkien is wading. He writes the novel in a mythic mode, and one of the conventions of myth is that it describes a past that is more glorious than the present. This sense of loss certainly is present in the Greek myths, for example, or in Homer’s epic poems that draw on these myths—both of which describe a world in which men and gods mix freely, a world that is no more. Tolkien’s own work is something between mythology and fiction, locating itself in a middle ground between a past that is remembered only in song and the everyday present of the reader. This sense of ancientness is constantly present, brought to life in chants, poems, and graven inscriptions. As Tolkien shows again and again—whether with the Elves or with the Númenóreans or the Dwarves—the stories that the characters tell define them. In some cases, as with Aragorn for example, this mythology explains not only where a character comes from, but also where he or she is going. The characters carry their past and their lore around with them, and they are virtually unable to speak without referring to this lore. The twist Tolkien adds is that these “myths,” while retaining all of the usual metaphorical resonance and symbolic simplicity, also happen to be true—at least in his world. This sense of reality within the novel, in turn, lends power to even the most everyday occurrences in Middle-earth.