text: William Kinderman's book about this work traces its compositional history and identifies late sketches for it in the Engel- mann Sketchbook.
full_question: William Kinderman's book about this work traces its compositional history and identifies late sketches for it in the Engel- mann Sketchbook. An Allegro fugue in this composition abandons its usual key and is instead in E-flat, though it modulates back to the main key after a cadenza-like passage consisting of a rising and falling sixteenth-note arpeggiation of a diminished seventh chord. Another section of this work parodies an aria for Leporello in Don Giovanni. The composer put his Missa Solem- nis on hold to begin work on this composition, despite having originally insulted its thematic material as a "cobbler's patch." This work appears in part I of the collaborative publication Vaterländischer Künstlerverein. For 10 points, name this piano composition, Beethoven's Opus 120, consisting of a set of variations on a waltz originally produced by an Austrian musician.
first_sentence: William Kinderman's book about this work traces its compositional history and identifies late sketches for it in the Engel- mann Sketchbook.
raw_answer: the Diabelli Variations [or 33 Variations on a waltz by Anton Diabelli; or Ludwig van Beethoven's Opus 120 until it is read; prompt on "Opus 120"]