about Sonata Form

 Fly, My Darling’s three sections (Allegro, Adagio, Allegro con brio) take their shape and thematic meaning from classical sonata form—a three-part musical structure where each movement explores a central theme or motif. Roughly: the first movement/section introduces the theme in a lively allegro tempo; the middle section challenges that theme, creating a counter melody somewhat slower and often dramatically pensive; the third returns to the opening theme’s original idea and quickened pace, occasionally in a different key.

Encyclopedia Britannica online has this further definition of the form’s second section/movement, a surprising—and stunningly accurate—description of Fly, My Darling’s middle section:

In sonata form, the point at which [the second of three parts] passes into [the third and final part] is one of the most important psychological moments in the entire sonata-form structure. It marks the end of the main argument and the beginning of the final synthesis for which that argument has prepared the listener's mind. The preparation for it is usually a long passage of gathering tension. As a result of the events in the development, the listener perceives the subjects in a new relationship rather like a traveler who glimpses the parts of a valley separately as he climbs a hill and then, when he reaches the summit, sees the entire landscape for the first time as a whole.

Sonata form! A classical musical structure. And a framework in which a narrative found its roots and flourished.