Beethoven's 29th sonata, Op. 106, a.k.a. the Große Sonate für das Hammerklavier, or more simply as Hammerklavier, is widely considered to be one of the most important works of the composer's third period and one of the great piano sonatas. It is considered Beethoven's single most difficult composition for the piano, with the possible exception of the Diabelli Variations, and it remains one of the most challenging solo works in the entire piano repertoire to this day. The sonata was written in 1817-18, towards the end of a fallow period in Beethoven's compositional career, and represents the spectacular emergence of many of the themes that were to recur in Beethoven's late period: the reinvention of traditional forms, such as sonata form; a brusque humor; and a return to pre-classical compositional traditions, including an exploration of modal harmony and reinventions of the fugue within classical forms.
