Bach Prelude in C major, bar 22

[groovizm]

Hi forum,

...

Bar 22 is F#dim, bar 24 is G7.

But what is bar 23?

Is that Abdim? Dhalfdim/Ab? And what is its function?

I would've had no problem if it went straight from F#dim to G7.

...

Well, I think you are absolutely right. Bar 22 is F#dim, what Walter Piston calls a secondary dominant, leading (your right again) to G7. The chord on Ab is indeed Ab diminished, or, more technically correct an inversion of B dim, which would normally resolve to C.

As I hear it Bach is taking a diversion here, instead of going from F# dim to G7, like you'd expect him to do, he moves his secondary dominant up a whole tone, which gives us another dominant chord, this time for C (minor). The Ab in the bass suggests the bass will be falling to G so what I'd expect to hear in the next measure is a fourth-sixth chord (C with G in the bass), wich would normally resolve to G7.

But here he tricks us again, he does not go to C/G, he goes straight to G7! Bach was a master of this kind of prolonged resolution, constantly playing with the listeners expectations.

[jancivil]

That (23) is a vii chord? it certainly does not sound like one as it does not work like it; it has a subdominant function in the context of the formal plan.

The B you have there is one of three passing notes in the tune and you have it as the root of a harmony. I do not buy this argument in any way. Posing JS Bach as block chords in this way is antithetical anyway.

The progression vii7 to V7 is fairly common

no shit, Sherlock. The problem is it doesn't sound like that because that isn't what happened.

and, as fmr said, the resolution of it here is textbook.

vii to V is a resolution? Who knew. that's two harmonies of the same function. &, the entire actual resolution included a couple of surprises for your textbook I guess.

The B in that chord cannot be a passing note, by definition it does not "pass" anywhere (unlike the C). It is an integral part of the chord.

B C D, what is that? which of these three tones of exactly the same rhythmic weight is integral? Are you trying to tell me that because it falls on the beat it has more meaning to the harmony? "By definition", well semantic quibbles do not make your argument any better, I'm sorry. B moves to C and D, dwelling on none of the three at all. The Ab and F ARE, OTOH unambiguous parts of the harmony and I do not see a reasonable objection to iv6, the simplest figure.

all of that is a tortured argument which seems to exist just for purposes of argumentation. To get a feel for how JS Bach did this stuff, follow my argument, it's a subdominant moving to dominant, simply enough. iv6 (or ii6/4), V7... and on iv (or ii, same difference) he anticipated V: B, C, D. This is classic JS Bach, which I am well familiar with as it was a focus of mine for a time.

And one more time for the world, JS Bach is contrapuntal practice; and much of this was extemporaneous with a ground or tune in mind. Employing Occam's Razor is just observing best practices here.