So I'm analyzing the harmony in Bach's C major Prelude from the Well Tempered Clavier, and it all goes smoothly until I reach this chord:
Now, most editions I see of this Prelude don't have this chord in it. I even have 2 piano books that both have this Prelude and they differ by exactly 1 bar because one of them has this chord in it and the other one doesn't, it just has the 2 diminished sevenths right next to each other. That doesn't necessarily mean that one or the other is wrong though, as I have seen happen with 2 editions of Mozart's K545 in the past, where the Andante in one edition had a false recapitulation before repeating the G minor and the majority of the others went straight to the G major with no false recapitulation whatsoever. So I treated it as though it was correct. And also, I was just curious about how I should go about analyzing a chord like this one.
If it is correct though, what chord is it? G, B, C, Eb, that spells a minor-major seventh chord on C, but that kind of seventh chord isn't used in Classical Music, so it's probably a triad with an added non-chord tone. But which triad? It could be G+, that certainly fits with how the chord sounds, calling it an augmented triad on the dominant. But, do augmented triads even get used at all in the Baroque? Earliest composer I have seen use an augmented triad is Beethoven and it doesn't become common until the Romantic Era with composers like Chopin and Liszt. Also, I wouldn't expect an augmented triad to move to a diminished seventh chord directly. I would expect it to move to either a major or minor triad by moving one of the notes by a half step up or down and then for the triad to go to a diminished seventh if I indeed see an augmented chord going to a diminished seventh.
The other option is that this could be a C minor triad with a non-chord tone B. That fits better with the diminished chords preceding and following it and with the style in general. I don't know though, I hear an augmented triad more than I do a minor triad in there.
This is what my analysis looks like with the mystery chord included:
Without that chord, the first of the 2 diminished sevenths is vii°7/V and the second is vii°42 of the tonic C major. With the mystery chord though, the vii°7/V becomes a Ct°7, because the Eb is a common tone. And so is the C if the mystery chord is a C minor triad with a non-chord tone B.
So, what chord is this? Is it the G augmented chord that it sounds like when I play it? Or the C minor triad that fits better with the style and the diminished chords?