Ricercar a 6 from Musical Offering BWV 1079 (Bach)

The theme was provided by Frederick the Great, King of Prussia, who challenged Bach with it during Bach's visit to Potsdam in 1747. Bach later composed the entire Musical Offering (BWV 1079) based on this royal subject and sent it to the king.

As the name indicates, the Ricercar a 6 is a six-voice fugue, making it one of the most complex fugues Bach ever wrote. It demonstrates Bach's mastery of invertible counterpoint by weaving the royal chromatic theme through six independent musical lines simultaneously.

The Musical Offering contains two ricercars: a three-voice version that Bach reportedly improvised at Frederick the Great's court, and the six-voice Ricercar a 6 that he composed afterward and included in the printed collection sent to the king. The six-voice version is far more intricate and is widely considered one of the pinnacles of contrapuntal writing.

Bach visited Frederick the Great's court in Potsdam in May 1747, at the invitation of his son Carl Philipp Emanuel Bach, who was employed there as a court musician. During the visit, the king gave Bach a difficult chromatic theme and asked him to improvise on it, which ultimately led to the creation of the Musical Offering.