Bach: WTC I, Prelude and Fugue in D minor

I don't often find myself chuckling when I listen to a Bach fugue, but I did with this one. More about that later.

The Prelude in D minor is the first instance of the use of triplets so far in the WTC. I don't know if a lot of study has been done of Bach's rhythmic techniques, but one thing we notice in the preludes is that each one focuses on a particular rhythmic structure, just varying it enough to be interesting. The typical mistake that beginning composition students make is to have too much variety. After two bars of something they want to do something contrasting. But notice Bach's practice. This entire prelude, except for the final cadence, is in triplets with the bass line in eighths. That's it! The variety comes almost exclusively from the harmonic progressions and the filigree of triplets just highlights that. The modulations are to closely related keys, such as G minor in mm. 6 - 8 and again in mm. 17 - 18. 

But the fugue is where Bach really has fun. This piece is all about inversion--not invertible counterpoint, though that can always be present--no, here Bach inverts the subject. Here is the subject in its original form:

And here is that same subject inverted where every interval is reversed--a step up becomes a step down and so forth (ignore the first eighth, the inverted subject starts on the F):

The subject, recto, appears five times on page one of the fugue (and three times on page two) while the inversion appears five times on page two. The first two appear in stretto and so do the third and fourth statements. Looking for appearances of the inversion, I started chuckling when I saw an incomplete version of it in mm. 14 - 15. He was prepping us. Can you call it a false entry if we haven't heard the whole inverted subject yet? Search me. Then in m. 21 we have the original subject with the inversion entering in m. 22 and another statement of the inversion in m. 23. So a stretto of the original theme with its inversion is immediately followed by a stretto of the inversion with itself. There are some more false entries here and there (a false entry is when we just hear the first part of the subject). What really got me chuckling was the penultimate measure where, in the right hand, Bach has the first part of the original subject, doubled in thirds, and in the left hand the inversion, also doubled in thirds. Yeah, ok we got it! Who says Bach didn't have a sense of humor?

Here is Sviatoslav Richter with the Prelude and Fugue in D minor. Incidentally, I don't choose his clips because he is the only good Bach player, but his seem to be the only ones with the score.