I think this is actually the most "strange" and perhaps also most interesting part of this movement. At the point you mention, m. 31-32 Mozart suggests us by using the dominant 7th chord Bb7 that we come back to the home key, Eb major, but he surprises us completely with this progression to Gbmajor, and, as you state, afterwards destabilizes the whole part through a series of sequencing modulations in the style of a development section. The relation between Bb7 and Gb is what I know as "third relationship", i hope this is the correct English term. Bb and Eb serve as pivot notes. This turn to Gb major has to me somehow the character of a deceptive cadence. M32, last quarter: Gb: V7. M 34: Gb. I-(V7): (M.35) II (V7): (M.36) III Now instead of going on with the sequence (the next step would be (V7):IV Cb major, Mozart leads us to c minor by using the dominant G major. M. 37. c: i- V- G: ii7- #IV6 with a diminished third(Ab) and 5diminished 7th (Eb) So in m. 38 we are in the dominant of c minor, G. but since now he wants to go back to Eb major he uses in m. 39 c: (VII7) i6 but this i6 does not appear, instead it appears a Eb: (V2) (F7) : V7(B7), the thirtysecond run in m. 40 is on the dominant of Eb major.I hope this makes at least a bit of sense, it is pretty complicated The chord on the last quarter in m. 37 is a typical Mozart chord which even has a particular name but I forgot this And the English name might be different anyway.Okay hope this helps, it's my first attempt of doing such a complex harmonical analysis in English. It's fun hopefully perhaps someone else will correct what I said, if it's wrong.
I hope that is clear. To sum up, I don't believe there is a tonal center per se, and so if you want to use Roman numerals (you don't have to for this section), keep them only according to the home key.Walter Ramsey
Hi, Walter. As I am working to get through some of this, I have a question on what exactly you mean in your wording in what I have quoted. Do you mean that for the entire movement, I would relate absolutely everything to Eb Major ?And, are you suggesting that with classical composers, one would always relate (even modulations) to *only* the original key ?
G-flat major, in 32, comes as a deceptive cadence to e-flat minor
Yes that is my question too as I am thinking of this. Plus I have a few other questions.I hear the e-flat minor somehow but...why should we treat it as a new tonal center? I mean, the deceptive cadence of e-flat minor would be c-flat major-which appears only later in mm. 37. But okay, I said myself that it has the character of a deceptive cadence. And, another question, this augmented sixth chord in m. 37 has also a seventh in it. So why should it be just an augmented sixth chord? there is f#-Ab-C-Eb so it is a seventh chord. I actually unfortunately don't remember it's name though and I won't try to post it here since it would sound actually complicated Argh I really try to read in my Butterworth book more, in the future
I think any cadence that doesn't end up as it would suggest is fair to call deceptive. I wish I had the score, but I remember the music at the last minute suggesting e-flat minor, and then moving into G-flat, but I think that the G-flat can be seen as the tonal center, similar to the analagous passage before in A-flat, which Mozart didnt modulate to.
In the last chord you mention, there isnt a seventh. A-flat to F-sharp is an augmented sixth, but A-flat to G-flat would be a seventh.
Okay, I see. But here I dare to contradict. Because I didn't mean Ab- F# with "the seventh". I mean F#- Eb and this IS a seventh, a diminished one actually. The root note of the chord is F# and it is placed on the alterated IV, at least that is how I learnt it, as far as I remember.