A.: SBB Mus. ms. Bach P 1059
Copy of the score by an unknown copyist dating from the 2nd half of the 18th century and coming from the estate of Johann Gottfried Schicht (1753-1823). Composer indicated as: del Sig. Bach.
B.: Society of the Friends of Music in Vienna XI 36271. Parts from the 2nd half of the 18th century. Copyist: Johann Heinrich Michel (c. 1745- after 1804). From the estate of Johannes Brahms.
C.: SBB Mus. ms. Bach P 471
Copy of the score by Anton Werner (c. 1840) of Source A above. Composer indicated as: da G. Seb. Bach.
This composition is also found listed in Breitkopf’s catalogue: Catalogo de’ Soli, Duetti, Trii…che si trovano in manoscritto nella officinal musica di Breitkopf in Lipsia. Parte IVta, Leipzig, 1763, p. 12.
The sources from the 18th century attribute this work either to the family name Bach or to C.P.E. Bach. Only as late as the 19th century is the definite attribution of this work limited to J. S. Bach. Using source A as a basis for the publication of this work in the BG, Wilhelm Rust, nevertheless, firmly asserted its authorship as being by J.S. Bach (BG IX, 1860). Philipp Spitta, in his biography (Vol. 1, p. 729) affirmed this assignation while expressing only slight reservations. J. S. Bach’s authorship was first decisively disputed in the middle third of the 20th century beginning in 1934 as found in an article by Werner Danckert appearing in the Beiträge zur Bachkritik I, Kassel, 1934, pp. 33-43, then in the MGG I (1949-1950) article by Friedrich Blume on J. S. Bach as well as in his essay “Neue Bachforschung” found in the Syntagma musicologicum, edited by Martin Ruhnke, Kassel, 1963, p. 453. Finally, there is a very extensive argumentation based on an analysis of style by Hans Eppstein in his Studien über J. S. Bachs Sonaten für ein Melodieinstrument und obligates Cembalo (Acta Universitatis Upsaliensis, Studia musicological Unpsaliensia. Nova series 2, Uppsala, 1966), pp. 176-181. The whole question surrounding the authenticity of this work was complicated even more by the obvious connection with the Sonata in Eb Major for Flute and Obbligato Harpsichord (BWV 1031), which appears in two other manuscripts are more closely connected to works that were specifically attributed to J. S. Bach; while, on the other hand, the music stylistically points to a composer of the generation that followed J. S. Bach.
E. Eugene Helm in his Thematic Catalogue of the Works of Carl Philipp Emanuel Bach, New Haven, 1989, lists this work as by C.P.E. Bach under the category “Possibly Authentic” (542.5 p. 117). Wolfgang Schmieder, in his BWV listing (Thematisch-systematisches Verzeichnis der musikalischen Werke von Johann Sebastian Bach. Bach-Werke-Verzeichnis, revised and extended edition, Wiesbaden, 1990) assigns C.P.E. Bach specifically and definitely as the composer. In light of more recent research, the “Kleine Ausgabe” of the BWV edited by Alfred Dürr and Yoshitake Kobayashi along with Kirsten Beißwenger, Wiesbaden, 1998, has added a question mark as follows: “BWV 1020….Carl Philipp Emanuel Bach (?)”, but still leaves the entry in the Anhang II (Works of Doubful Authenticity) section while adding the following comment: “The apparently dependable/reliable attribution listing C.P.E. Bach as the composer has been called into question by (further) critical, stylistic analysis provided by Ernst Fritz Schmid in his C.P.E. Bach und seine Kammermusik, Kassel, 1931, pp. 120ff, 176, by Yoshitake Kobayashi in the Bach-Jahrbuch (1978), pp. 52ff., and by Ulrich Leisinger and Peter Wollny in the Bach-Jahrbuch (1993), pp. 192-196. The latter authors reaffirm Schmid’s original conclusion that the work was “wahrscheinlich nicht echt” (“probably not a genuine/authentic composition by C.P.E. Bach”). There is no implication here that this could mean that J. S. Bach might once again be considered as the composer.
Schmieder’s attribution to C.P.E. Bach can be related to source B above and the Breitkopf catalogue listing from 1763. Also, Ulrich Siegele in his Kompositionsweise und Bearbeitungstechnik in der Instrumentalmusik Johann Sebastian Bachs (Tübinger Beiträge zur Musikwissenschaft, Vol. 3), Neuhausen-Stuttgart, 1975, p. 45; Alfred Dürr in the foreword to the preceding research article; Robert L. Marshall in his “J. S. Bach’s Compositions for Solo Flute: A Reconsideration of their Authenticity and Chronology” in the Journal of the American Musicological Society 32 (1979) – the latter also appeared in Marshall’s The Music of J. S. Bach. The Sources, the Style, the Significance (New York, 1989, pp. 201-225); and Yoshitake Kobayashi in his article entitled “Neuerkenntnisse zu einigen Bach-Quellen an Hand schriftkundlicher Untersuchungen” Bach-Jahrbuch, 1978, pp. 43-60 and “Breitkopf Attributions and Research on the Bach Family” in Bach Perspectives, Vol. 2: J. S. Bach, the Breitkopfs, and Eighteenth Century Music Trade edited by George B. Stauffer, Lincoln, 1996, pp. 53-63, continued in favoring a possible ascription of this work to C.P.E. Bach. Christoph Wolff’s updated (2008) article on Bach’s works in the Grove Music Online article on Bach still hearkens back to this earlier stage of research into this matter (BWV Verzeichnis “Kleine Ausgabe”, 1998), placing this composition into the “Doubtful, Spurious” category of J. S. Bach’s works as “BWV 1020; Sonata, g, hpd, vn (?) by C.P.E. Bach”.
Schmid, Kobayashi, Leisinger and Wollny have determined that this composition does not fit stylistically into C.P.E. Bach’s oeuvre, even into his early period. Possibly, however, the composer belonged to the same generation of composers as the Bach sons. A very comprehensive and detailed discussion of this work is offered by Barthold Kuijken in his epilogue to his recent edition of this music: Bach (?) Sonate für Flöte (Violine) und Cembalo g-moll, hrsg. und kommentiert von Barthold Kuijken, Wiesbaden (Breitkopf & Härtel), 2003. Kuijken concludes that this sonata is neither by J. S. Bach nor his son, C.P.E. Bach.
In a fairly recent study by Keiichi Kubota (his C.P.E. Bach. A Study of His Revisions and Arrangements, Tokio, 2004, pp. 153-157 and p. 165), the author speculates that it is possible that this composition resulted from a collaborative teaching effort between father and son. Kubota does not give any details or reasons that may have led him to his speculative conclusion.
During the past 30 years or so, numerous critical editions of this music have been published. In addition to the most recent edition (2003) by Kuijken listed above, there are also the following:
Bach. Sonate C-dur für Flöte und Basso continuo BWV 1033, Sonaten Es-dur, g-moll für Flöte und obligates Cembalo BWV 1031, 1020 (these are offered as genuine works by J. S. Bach), editor: Alfred Dürr, Kassel (Bärenreiter), 1975
Joh. Seb. Bach. Sonaten für Flöte und Klavier (Cembalo), Heft II (3 Sonatas attributed to J. S. Bach), editor: Hans Eppstein, München (He), 1981
Carl Philipp Emanuel Bach. Zwei Sonaten für Querflöte und obligates Cembalo g-moll, Es-dur , editor: Oskar Peter, Winterthur (Amadeus), 1989
Joh. Seb. Bach. Sonaten für Violine und Continuo BWV 1021 und BWV 1023. Anhang: Sonate für Violine und obligates Cembalo BWV 1020, editor Hans Eppstein, München (Henle), 1990
Since the careful examination of sources and the analysis of style offered no reason to attribute this work to J. S. Bach, the NBA, in its NBA KB VI/5 published in 2006, has decided not to recognize it, but rather reject it as an authentic or even possibly authentic composition by J. S. Bach. As a result, the music for BWV 1020 does not appear in print in the NBA.