피아노 소나타 21번 (Piano Sonata no. 21 in C major, op. 53, "Waldstein")

Beethoven's Piano Sonata No. 21 in C major, Op. 53, known as the Waldstein, is one of the three most notable sonatas of his middle period (the other two being the Appassionata, Op. 57, and Les Adieux, Op. 81a). Completed in summer 1804 and surpassing Beethoven's previous piano sonatas in its scope, the Waldstein is a key early work of Beethoven's "Heroic" decade (1803–1812) and set a standard for piano composition in the grand manner. The sonata's name derives from Beethoven's dedication to his close friend and patron Count Ferdinand Ernst Gabriel von Waldstein, member of Bohemian noble Waldstein family (Valdštejn). It is the only work that Beethoven dedicated to him. It is also known as L'Aurora (The Dawn) in Italian, for the sonority of the opening chords of the third movement, thought to conjure an image of daybreak. It is considered one of Beethoven's greatest and most technically challenging piano sonatas. The first section of the rondo requires a simultaneous pedal trill, high melody and rapid left hand runs, and the coda features octave glissandi written in dialogue between the hands. An average performance of the entire Waldstein lasts about twenty-five minutes.