This number contains some interesting changes. The overall form is 16+16, where the first 8 bars of each 16 are identical (ABAC structure).

At the start it immediately modulates to bVI, a key 4 flats flatter than the tonic, using a pivot on the 5th in the original key (leading note of bVI), then returns to the tonic.

It does a 2-5-1 to the subdominant. In the first 16 the cadence is interrupted, and it leads to the minor subdominant, which is then used as ii of bIII. In the 2nd 16 the 2-5-1 to the subdominant behaves normally.

Pivot on 5th (3rd of bIII) 5-1 Mod to bVI			b11M to ii
I	bIIIx	bVIM	bIIM
2-5-1			251 Mod to IV
ii	V	I	vm Ix
interrupt with ivm instead of IV	Mod to bIII		bVIM to ii
ivm	bVIIx	bIIIM	bVIM
2-5-1		turnaround
ii	V	I vi	ii V
Repeat
		circle of 4ths via IIx
IV	ii V	iii vi	IIx
ii	V	I	I