At the beginning of The Fellowship of the Ring, Tolkien deliberately links the trilogy to its predecessor, The Hobbit. He describes the return of Bilbo, Gandalf, and the Ring and, in the prologue, he expands the nature of hobbits and summarizes the story of Bilbo and Gollum.

The narrative at first continues the light spoken tone of the earlier novel, but as it develops, this tone recedes, only occasionally bursting forth in the words and actions of the irrepressible hobbits.

The author creates two major challenges for himself in structuring the three volumes: deepening the story's historical dimensions and uniting the many narrative strands. To make Frodo's quest part of a more cosmic struggle, Tolkien continues evolving the history of Middle-earth, using Gandalf and Elrond to relate the ancient history of Sauron, the Lord of the Rings, and supplying many glimpses of the mythological and legendary...