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:

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:

3. Anticipate the G in the soprano:

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

5. Delay the fourth half-note:

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

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

Happy New Year!