In The Lord of the Rings Tolkien has demonstrated the evolution of a literary world. In The Hobbit, often considered a prologue to the trilogy, he created a fascinating kind of being with no parallel in literature; in the trilogy he expands his single hobbit hero into four hobbit companions and an interesting assortment of helpers and enemies. Readers who were captivated by Bilbo in The Hobbit will encounter him again in The Fellowship of the Ring, the first volume of the trilogy. Bilbo's nephew Frodo is a more developed character than Bilbo and therefore even more absorbing to watch in action. The trilogy exemplifies Tolkien's power to sustain a central adventure through three volumes, each divided into two books. Each of the six books builds up to its own climactic ending, but an intricate system of interlacing allows the reader to move easily with the characters as...