Storytelling
In an explicit sense, Bilbo, Frodo and Sam are engaged in a literary endeavor, involving the chronicling of their adventures. After a major event has occurred, Sam often wonders how the story will be remembered and whether his own heroics will be forgotten. More often than not, the stories of the heroes that are presented in the trilogy are in a song form, rather than a written literary form. Many of the songs are Elvish and towards the end of The Return of the King, many of these songs are prophetic in nature, with Aragorn appearing as the foreshadowed King. Many of the present heroes are related to former heroes or presently engaged in some quest that originated in an anterior mission (for example, Frodo's quest of the Ring is the result of Bilbo's earlier adventure with the Ring). As a result, the songs are often celebratory (in regards to the past) and prophetic (in regards to the future).
Aging
Aging is a complicated theme in this last novel of the trilogy. On one extreme, we find Bilbo Baggins, who has become a very elderly (but also very sleepy) hobbit. His recurrent sleep prefigures the symbolic death that occurs in the sailing towards the Grey Havens. Even on the ride to the sea, Bilbo is half-asleep on his horse. Throughout the trilogy, the elves have represented a symbolic youth and regeneration. The passing of Galadriel and many elves certainly dampens the illusory hope of "eternal youth" that surrounded the elves. Indeed, the connection between the elves and "midsummer" is another symbol of extreme youth and lifethe greatest promise. There are various remnants of this old youth that remain: Arwen, Elanor, the mallorn tree and restoration of the Shire vegetation are a few examples.
Conservation and Heritage
One of the arguments of the Trilogy is that the present generation has an obligation to take care of its own problems and not leave them to the next generation to sort out. The entire expedition regarding the Ring, is designed with this understanding in mind. The various dynasties and traditions of Middle Earth all presuppose an idea of cyclical nature. The opposite of this balance (chaos) is found in Denethor's attempt to burn his son (and heir) on a funereal pyre.
Bravery, Prophecy and Fate
The Trilogy raises the question of whether heroism is a matter of individual will-power or a matter of fate. The success of some figures, like Aragorn, is foreshadowed by prophetic songsbut not all of the songs actually come to pass. Other times, prophecy is accomplished in an unintended manner. Gandalf suggests that Gollum may actually prove of use in the end, and for a time, Gollum seems truly repentant and helpful. Ultimately, it is Gollum's theft that destroys the Ring: he does good despite his bad intentions. Conversely, Frodo is considered to be a success even though his will power failed him at the end. Aragorn began the Trilogy as "Strider." His metamorphosis into a greater hero parallels the progression of names (from the prophetic songs) that are applied to him: Strider, Aragorn, King Elessar, the Elfstone.
About The Return of the King
The Return of the King is the third novel of the Lord of the Rings Trilogy. Tolkien began this trilogy well after the "world" of Middle Earth had been created. Several of the characters presented in this novel were first presented in The Hobbit. The Silmarillion, Tolkien's major mythological masterpiece, also presents an extensive history and language system that was already in place (though The Silmarillion was published posthumously). Much like the stories of Greek mythology, these stories present a history of the different "ages" of the world. The trilogy takes place in the Third Age.
The Middle Earth is a complicated mythology, out of which the story of Lord of the Rings grows and on which it is deeply dependent. Besides this mythological aspect, some critics also see Tolkien's work as a reflection on the horrors and politics of the Second World War. The delineation between the East and the West is also revealing. While the reader should avoid taking these insights to the extreme, this is an added context that makes the work more complete. It is well worth noting that this storyline was invented before the war, but it must have altered Tolkien's thought.
Finally, we should note Tolkien's role as an academic at Oxford University. His study of ancient and Anglo-Saxon languages certainly played a role in his invention of language systems. We can also look at the importance of saying certain words or not saying other words. Tolkien's Christian perspective also plays a role in his organization of Middle Earth. He and his colleague, C.S. Lewis, both create worlds that seek to understand the role of the individual's free will and the ability to choose between good and evil. The power-play between the forces of freedom and the dark lord, Sauron, simulate the battle between good and evil on earth.