The The Art of Fugue reference article from the English Wikipedia on 24-Apr-2004
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The Art of Fugue

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The Art of Fugue (Die Kunst der Fuge), BWV1080, is an unfinished and posthumous work by Johann Sebastian Bach composed in 1748-1749 and published after his death in 1750. The work is considered to contain some of the most complex fugues ever written, as well as some canonss.

The piece is written in score which does not make it clear exactly what medium or instrument(s) are called for. It has been performed and recorded by harpsichordists, pianists, organists and string quartets among others, and parts have also been arranged for orchestra.

Each of the fugues use the same, relatively simple, subject in D minor:

Image:Kunst_der_fuge_opening.png

The final fugue, left incompleted at Bach's death, includes the so-called BACH motif (the notes B-A-C-H as in German nomenclature, in which B is B flat and H is B natural) just before it stops abruptly without cadence or resolving to a true end. The most famous "completions" of the final unfinished fugue have been composed by Donald Tovey and Ferruccio Busoni.