LotR -- Book 2 - Chapter 05 - The Bridge of Khazad-dûm

[tar-ancalime]

Book Two is he allegro movement in which the important themes are glimpsed from time to time, but the motive of the movement is to thrill us with the possibilties of extension beyond the rather confining parameters of the opening. The Gandalf theme, for example, so heroic and wise, is placed into an awkward harmony with the Balrog, and both fall into oblivion, which allows the hints of melancholy and darkness, held at bay in the first movement, to be brought to the fore.

What you're describing is very much like the development section of a sonata-allegro form, in which the existing themes are segmented, extended, transposed, and recombined in what is often the most complex part of the work--it stands between the exposition, in which the themes and the principal tonal conflict are introduced, and the recapitulation, in which the tonal conflict is resolved (material which earlier appeared in a contrasting key returns in the home key). The development stands between these two sections and its purpose is to introduce new possibilities into the existing material, usually complicating the aural landscape and creating new conflicts that must be resolved before the principal conflict can be addressed in the recapitulation.

(*tar-ancalime takes off Pompous Lecture Hat.*)

I think your analogy is apt, at least this far into the story. Book One introduces many of the themes and the principal conflict; Book Two begins the journey to resolve that conflict, which must be complicated on the way by obstacles foreseen and unforeseen. Perhaps, though, the analogy is so apt because this is the basic pattern for most of the stories we tell in our culture, whether musical or literary. Are the novel and the symphony always so compatible? But I can feel myself straying farther and farther from the topic at hand, so I'll restrain myself for now.

To return to the specific chapter at hand, the whole journey in Moria is foreshadowed by another underground "adventure"--the Barrow-Downs. An idea first presented in Book One (exposition) returns in Book Two (development) with new repercussions, in a different "key."