Johann Sebastian Bach wrote his six cello suites between 1717 and 1723, while he was employed as a court musician at the court in Coethen. They were written for one of the court cellists (probably Carl Friedrich Abel), and show a level of virtuosity unusual for cello writing of the time.

The suite¹, like the sonata, emerged out of the need to develop a suitable form for instrumental music. Choral music had reached a plateau in the 16th Century, and instrumental music was becoming more and more important. A suite was a set of instrumental compositions, generally similar in style to each other but also providing a certain amount of contrast and variety in speed and rhythm. The movements of a suite would be various dances, and in Bach's time the sequence Allemande - Courante - Sarabande - Gigue was an established one.

Each of Bach's cello suites is in six movements.

First is a Prelude, similar to those in his '48 Preludes and Fugues'. This is a free improvisatory piece in a single style, based on a small motif or pattern. It is the one movement of a suite that is not based on dance style. It sets the mood for the suite, and is often thematically related to the other movements, which are all stylised dances.

Then follows an Allemande, a stately French or German dance (Allemande is the French word for 'German'), in 4-time, with a prominent upbeat - a short note before the main beat. Its general character is serious but not heavy.

Next comes a Courante (literally 'running'), a lively dance in 3-time. Bach's cello suites contain examples of the both the Italian and French styles. The Italian style is with semiquavers and quite vigorous, while the French style tends to quavers and is a little more refined.

The fourth movement is a Sarabande, a slow dance originally from Spain (or possibly of Oriental origin and developed in Spain). This is in 3-time, with a strong emphasis on the second beat. This movement frequently contains the emotional heart of the suite, and the remaining movements to an extent relax away from it.

The final movements are a pair of contrasting Minuets, Bourrées or Gavottes (depending on the suites), followed by a boisterous Gigue. This dance in compound time is not a dance of the court like the others, and would have been familiar to ordinary people (its English equivalent is the jig).

Such a formulaic pattern may give the impression that the suites are repetitive and monotonous, but this is not so. Each dance movement is explored so fully by Bach that, by the end, he has used these structures to express deep and profound emotion. This is not easily explained in words - listen to the suites for yourself!

No manuscript of the cello suites exists in the composer's own hand, and the suites were lost for many years². There are, however, copies of the six cello suites believed to have been made by Bach's second wife, Anna Magdalena Bach. Although movements were used as teaching exercises, the suites were not performed as pieces until the late, great Catalan cellist Pau (or 'Pablo') Casals rediscovered them early in the 20th Century. He studied them for 20 years before performing them in public, and was still playing them in his 80s.

Many recordings are available, and the interpretations in them are varied. Sometimes these suites are played on a baroque cello rather than a modern instrument.

The fifth suite is written for scordatura (meaning that the A-string is tuned down to G), and the sixth suite is actually written for a 'cello piccolo', with an E-string a fifth higher than the normal high A-string. This makes the sixth suite perhaps the most technically demanding of the suites for modern-day cellists, as hardly anyone has a 'cello piccolo' any more.

Some cellists prefer to play this music on a baroque cello, whose sound (and bowing technique) is a bit different from modern cellos. Others try to approach the 'baroque' sound and style even when playing on a modern cello, whereas others keep to the sort of style preferred by Casals. For a discussion of the problems and challenges of performing and interpreting Bach's cello suites see 'Interpretational Angst and the Bach Cello Suites'.

But however they are played, JS Bach's cello suites form an absolutely essential part of today's cello repertoire.