Opus clavicembalisticum

Opus clavicembalisticum is a solo piano piece composed by Kaikhosru Shapurji Sorabji, completed on June 25, 1930.

The piece is notable for its length and difficulty: at the time of its completion it was the longest piano piece in existence. Its duration is around four hours, depending on tempo. Several of Sorabji's later works, such as the Symphonic Variations for Piano (which last probably about nine hours of music) are even longer.

At the time of its completion, the piece was possibly the most technically demanding solo piano work in existence due, for the most part, to its extreme length and rhythmic complexity and to the vast resources of physical and mental stamina demanded by its many passages of transcendental virtuosity, although some works conceived by New Complexity, modernist and avant-garde composers, along with Sorabji himself, were more difficult still; it is in this particular area that Opus clavicembalisticum primarily receives its notoriety, and to this day is still highly regarded in that light.

Sorabji may in part have been inspired to compose the work after hearing a performance of Busoni's Fantasia contrappuntistica by Egon Petri, and Opus clavicembalisticum to some degree embraces an homage to Busoni's work. Sorabji's earlier (1928) Toccata No. 1, also for piano solo and likewise a multi-movement work, evidences similar Busonian influence and is in some ways a precursor of Opus clavicembalisticum.

Opus clavicembalisticum has twelve movements, of hugely varying dimensions: from a brief cadenza, lasting only three minutes, to a mammoth , containing a , adagio, and passacaglia (with 81 variations), requiring around an hour to play. The work's movements are set in three parts, each larger than the last:

In a letter upon completion of the massive work, Sorabji wrote to a friend of his:

With a wracking head and literally my whole body shaking as with ague I write this and tell you I have just this afternoon early finished Clavicembalisticum... The closing 4 pages are so cataclysmic and catastrophic as anything I've ever done—the harmony bites like nitric acid—the counterpoint grinds like the mills of God...

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Wikipedia