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Johann Sebastian Bach (1685-1750)

Image from the score of 'The Well-tempered Clavier'

J.S. Bach: 'The Well-tempered Clavier'
British Library Add. MS 35021, f.14.
Copyright © The British Library Board
A high-quality version of this image can be purchased from British Library Images Online. For more information email

JS Bach's set of 48 Preludes and Fugues, spanning all 24 major and minor keys twice each, is one of the cornerstones of Western art music. This autograph manuscript, of the A flat major fugue from the second set of 24, shows Bach's characteristic musical handwriting: beautiful and curvaceous, but also meticulous and clear.

Who was Bach?

Johann Sebastian Bach (1685-1750) is one of the great composers in Western musical history. He was born in Eisenach, Germany, into a family of working musicians. In 1695, when he was just nine years old, his parents died and he was sent to live with his brother, Johann Christoph, an organist. Whilst living with his brother he learnt the keyboard and studied composition on his own.

He worked as an organist, then as a court composer at Cöthen (now Köthen) and then as musical director at St Thomas's church in Leipzig, producing many hundreds of choral and instrumental works (and hundreds of thousands of pages of handwritten parts).

Bach married twice and fathered eight surviving children, three of whom became notable composers in their own right. He was a devoutly religious man, and knew tragedy: his first wife died suddenly while he was away on business; 12 of his 20 children died in infancy; one of his sons had severe learning difficulties; and another ran away from home in his teens and died in mysterious circumstances. With employers, who rarely appreciated his talents, he was chippy and argumentative; at a family gathering with a few drinks and a pipe of tobacco, however, he was robustly good-humoured, especially when the Bach clan took turns to improvise rude country songs.

What is special about his music?

Bach's style is baroque, characterised by lots of notes, simple motoric rhythms, and steady shifts of underlying harmony - it was derided by some as 'sewing-machine music'. But he explored harmony much more deeply than other composers of the time: compared to say Handel or Vivaldi, Bach's music can contain extraordinarily 'jazzy' chords and surprising dissonance, and will jump off to many different harmonic areas.

It is also 'absolute music' - in other words, it often seems to exist apart from any particular instrument, as a constructional idea by itself; consequently the same piece can work as effectively on a piano as a guitar, as a choral work or an orchestral arrangement.

Image of Johann Sebastian Bach

Johann Sebastian Bach's catalogue of works, listed by their BWV number (from the German 'Bach-Werke-Verzeichnis', 'Bach-work-catalogue') runs to over a thousand items

What was Bach's reputation?

Bach's thousand-plus works enjoyed relatively little appreciation in his lifetime. His music was considered a little old-fashioned for its time, enjoyed only by connoisseurs. The authorities at Leipzig famously complained that they only employed Bach because "the best [Telemann] was not available". Bach's main reputation was not as a composer, but as an astoundingly gifted organ player and improviser, and consultant for organ repair.

By the 1840s he was largely forgotten except to historians, but Felix Mendelssohn revived Bach's 'St Matthew Passion', and musicians steadily rediscovered his extraordinary body of work.

What is a fugue?

Bach excelled at counterpoint - the composition of two superimposed independent lines so that each makes musical sense by itself, but also combines seamlessly with the other.

He excelled even more at the fugue, a glorious but fiendishly difficult contrapuntal musical form. A fugue is a kind of musical chase between two or more lines. The first line starts; after a few seconds the second line joins in. It is slightly higher or lower than the first, but otherwise almost identical. A third or fourth line may join. The skill of a fugal composer is to make the lines develop independently, yet still fit together, while making each line recognisably a delayed variation of the preceding one. Such was Bach's expertise on the organ that he could improvise a four-part fugue.

Bach's preludes and fugues for keyboard are one of the landmarks of western classical music. For each major and minor key of the 12 notes of the scale there is a free-flowing prelude, followed by a tightly-constructed fugue, totalling 24 preludes and 24 fugues. He wrote two such sets, making 48 in all. They are often referred to as 'the 48', or by the more general title 'The Well-Tempered Clavier'.

'Clavier' simply means 'keyboard instrument'. The pieces are usually played on the piano nowadays; in Bach's lifetime the instrument was still being developed, and they would most commonly have been played on a harpsichord.

The 'well-tempered' refers to the piece's demonstration of how consistently the instrument is tuned across different keys, though exactly which tuning system Bach had in mind is the subject of much scholarly debate.

What does this image show?

Like much of Bach's work, 'The Well-tempered Clavier' was not published in his lifetime, but circulated in manuscript form. In its present state it contains 21 of the 24 preludes and fugues in all the keys. Most were written out by Bach, though a few were copied by his second wife Anna Magdalena. The preludes and fugues are written back to back on large sheets of paper which were originally folded but not bound.

Apart from a single fugue in Berlin, this is the only autograph manuscript of the second book to survive. It shows the beginning of the fugue in A flat major - you can see the second voice (which comes in halfway across the top line) imitating the shape of the first at a higher pitch.

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