Sonata in G major for two flutes and basso continuo, BWV 1039
- Allegro ma non presto
- Adagio e piano
This sonata, scored for two transverse flutes and continuo, is one of the few trio sonatas that can genuinely be attributed to Bach. Although traditionally thought to have been composed during Bach's period in Weimar or Cöthen, Bach scholars have revised that dating based on an analysis of the extant manuscripts and on stylistic considerations. According to Wolff (1994), the trio sonata was composed between 1736 and 1741 in Leipzig, where, since 1729, Bach had been director of the Collegium Musicum, a chamber music society performing weekly at the Café Zimmermann. The version for viola da gamba and harpsichord, BWV 1027, as well as the other two sonatas for this ensemble, are dated by Laurence Dreyfus, Christoph Wolff and others to the same period.
There is a third version for organ, the trio sonata in G major in three movements (BWV 1039a and BWV 1027a): its first two movements are organ transcriptions of the first two movements of BWV 1039; its last movement is a transcription of the fourth movement of BWV 1027. According to the Bach scholar Russell Stinson, the transcription for organ was not made by Bach, but probably by Johann Peter Kellner.
- Cyr, Mary (1989), "Review: Three Sonatas for Viola da Gamba and Harpsichord (BWV1027-1029) by J. S. Bach, Hans Eppstein, Lucy Robinson, Laurence Dreyfus and Jean-Louis Charbonnier", Early Music, 17: 106, 108, 110, 113, JSTOR 3127270
- Williams, Peter (2003), The organ music of J.S. Bach, Cambridge University Press
- Wolff, Christoph (1994), "Bach's Leipzig Chamber Music", Bach: Essays on his life and work, Harvard University Press, pp. 223–238, ISBN 0674059263