Yale music professor Craig Wright breaks down sonata-allegro form in this lecture from Listening to Music (MUSI 112), identifying four functional types of material within a sonata: thematic, transitional, developmental, and cadential. He then turns to theme and variations form, drawing examples from Beethoven and Mozart to show how composers rework a musical idea across successive statements. The lecture closes with a live demonstration featuring guest artist Kensho Watanabe, performing Corelli's La Folia to illustrate variation technique in practice. Recorded in Fall 2008, the session moves from formal definitions through worked musical examples to a real performance, giving listeners a structural vocabulary for hearing how classical pieces are built and varied. Chapter markers divide the hour into introduction, form overview, functional analysis, variation form, and the closing Corelli performance.