No, I won’t go into the manifold questions of interpretation here, and on the whole debate pro/con “historically informed” performance. What do you do when there is even no agreement on what the correct notes are?
The other day I heard somebody play Liszt’s piano arrangement of Bach’s Fantasy and Fugue in G minor for organ, BWV 542. The Fantasy happens to be one of my two favorite pieces ever in the entire organ literature (the other being the Passacaglia and Fugue in C minor, BWV 582), so I’m very familiar with its twists and turns.
So I was struck by two “mistakes” that stuck out like sore thumbs:
(1) in one of the solo recitativo bits of the Fantasy, the pianist hit a loud F natural where I’d always played a D (and as the last preceding chord was Bm/D, the F made no harmonic sense to me), and
(2) he played the final chord of the fantasy as G major rather than G minor. (Such a “Picardy third” — ending a minor-key piece on a major triad — was still the norm in Bach’s time, as minor thirds were still considered mildly dissonant. Bach himself, however, would end minor-key preludes in the Well-Tempered Clavier on minor triads to indicate the fugue was still to follow.)
Google Scholar is your friend then, and it turns out not only is there an entire academic journal called Bach, but that a long essay in it had been dedicated to the source provenance and variant readings of exactly this piece.
William H. Bates, “J. S. Bach’s Fantasy and Fugue in G Minor, BWV 542: A Source Study for Organists”, Bach 39(2), 1-88 (2008).
Turns out that no original manuscript has been preserved, but the piece has been transmitted through multiple first- and second-generation manuscript copies by pupils of Bach, their pupils, and by an anonymous copyist at a royal library. [*] What’s more: for the fugue, they appear to derive from at least three different source versions: an original, Bach’s later emendation, and a version transposed to F minor. Dozens of minor discrepancies exist.
For the fantasy, of which appears to have been substantially only one source version, there are “only” three outright variant readings in the notes. Aside from the final chord noted in (2), they are a comparatively trivial change at bar 42 and the one noted in (1):
Thus the mystery is solved. The score I have, a Dover paperback, is a reprint of the BG (Bachgesellschaftedition, or Bach Society Edition, b. above) — which is followed in many classical organ recordings. The Liszt piano arrangement I heard was based on a different source (a. above) — it seems that the source material (c,d) had a oddball “E” (presumed transcription error) which had been editorially corrected in two different ways:
a. consistent with a later occurrence of the phrase in bar 44 (a fourth higher), which is the choice made by the Bärenreiter and Breitkopf & Härtel editions;
b. consistent with the preceding chord (Bm/D), which is the choice made by the Bach Society Edition after 1900 (originally they printed the E).
Also, I learned from this article that the Fantasy and the Fugue appear to have been entirely separate compositions, which (because of their compatible keys) were paired by custom, sometime after Bach’s death. This offers a clue as to the “Picardy third” mystery: as minor thirds were still considered mildly dissonant in Bach’s time, final movements of minor-key works still customarily ended on major triads, though Bach would often end a minor-key prelude on a minor third if there was another movement to follow.
“The lonely lives of classical music scholars”, you say? Maybe that too, but also, for this scientist and amateur musician:
(a) a sobering observation on what exactly constitutes “authenticity” in classical music performance;
(b) an interesting parallel with great literary works from the English Canon hat were only printed after the author had passed away.
[*] Unlike for works like Toccata and Fugue in D minor, BWV 565, there is ample internal and external evidence that J. S. Bach was the author of BWV 542.