It is "generally thought to have been composed at Cöthen in 1717-23",[1] although Christoph Wolff has raised the possibility that the work may have been written in Leipzig,[2] perhaps during Bach's time as director of the Collegium Musicum. In any event, the only autograph source to survive are parts Bach copied out (along with other copyists)[3] in Leipzig circa 1730 [4] from a now lost score or draft.