For 10 points, identify this work in C major, Beethoven's Sonata 21, dedicated to and named for Count Ferdinand Ernst, the composer's then patron.
This work's second subject, in E major, introduces a moment of tranquility, but is soon overtaken by the rhythmic intensity of the main theme. In the finale, that main theme, a seven note melody, begins quieter, then transforms into ecstatic celebration, and is marked Rondo (Allegretto moderato). This work, which opens with a pulsating progression, originally included an Andante favori at the beginning of the final movement, but this was a replaced by a shorter Adagio introduction. Its composition was preceded by the composer's acquisition of an Erard fortepiano in 1803. For 10 points, identify this work in C major, Beethoven's Sonata 21, dedicated to and named for Count Ferdinand Ernst, the composer's then patron.
This work's second subject, in E major, introduces a moment of tranquility, but is soon overtaken by the rhythmic intensity of the main theme.
The "Waldstein" Sonata [or Sonata No. 21 in C major, Op. 53; accept either underlined part before it is mentioned]