Bach by popular demand…

December 31, 2008

Well, as requested, at any rate…

Here is an analysis of the first two measures of the B-flat major Prelude from WTC I.

Warning: this analysis breaks some of the rules (well, one in particular) of strict Westergaardian theory as expounded in ITT. In fact, it does so twice (at two distinct stages). Exercise: see if you can identify the rule that is broken, and give a convincing rationale for relaxing it.

1. The basic structure:
bachwtc21ex01

2. Segment the final two beats of the first span with: an incomplete neighbor in the bass, a complete neighbor in the soprano, a borrowing from the bass in the alto, and a rearticulated suspension in the tenor:
bachwtc21ex02

3. Anticipate the G in the soprano:
bachwtc21ex03

4. Borrow from these structural lines to create the texture of the passage:
bachwtc21ex04

5. Delay the fourth half-note:
bachwtc21ex05

6. Elaborate further (the operations being, I hope, clear):
bachwtc21ex06

7. Elaborate still further to obtain the passage as Bach gave it to us:
bachwtc21ex07a
bachwtc21ex07b

Happy New Year!

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