Sonata form is the most commonly encountered organizational plan in the works of the classical-music masters, from Haydn, Mozart, and Beethoven to Schubert, Brahms, and beyond. Sonata Theory, an analytic approach developed by James Hepokoski and Warren Darcy in their award-winning Elements of Sonata Theory (2006), has emerged as one of the most influential frameworks for understanding this musical structure. What can this method from "the new Formenlehre"...