Bach: WTC 1, Prelude and Fugue in B flat minor

Since there are only three left, I want to wrap up this project of surveying all the preludes and fugues in Book 1 of the Well-Tempered Clavier. At five flats, this key is far out on edge of possible keys in the 18th century. Indeed, the next generation would rarely go beyond three or four accidentals. Possibly because of the remote key, I notice a significant expressive difference in the harpsichord version of the prelude in particular. Here is Kris Verhelst in a performance for the Netherlands Bach Society:

As you can hear in the first couple of measures of the prelude, even seconds and augmented seconds sound rather "crunchy" in this temperament. (I'm not good enough to tell which one she is using, but likely Werckmeister III or something similar which is usable in all the keys, but some are crunchier than others.)

Now here is Sviatoslav Richter and the poster has kindly included not only the score, but marked the entries of the subject in red and answers in blue.

The prelude sounds so much more smoothly consonant on the piano. That is a lovely prelude, in its measured stride reminding me of some of the choruses from the St. Matthew Passion. But let's take a close look at the fugue. Here is the extremely simple subject:

And the answer:

And that's it. As far as material goes you can't get much simpler. The only distinctive thing about this subject, and something that we have not seen before, is the gigantic leap of a ninth to the third note. Bach subjects typically tend to be rhythmically active, but generally move by step. This is the largest leap we have seen in one of his subjects, I believe. There also isn't a very distinctive countersubject.

The fugue unfolds pretty much as you would expect. It is in five rather than three or four voices and the entries are interspersed with free counterpoint. No inverted subjects and no strettos until the end. One of the nicest effects is an entry on the relative major, D flat major, in m. 25 followed by an answer on E flat minor. But just when it seems we will continue in E flat minor, Bach gives us another entry on D flat major in m. 37 that is given a harmonically haunting context. Things are fairly normal from then on until m. 67 when Bach gives us a very tight stretto at the half note (i.e. one note delayed) of all five voices from the soprano on down. Given the nature of the theme that means that the first note of the second entry is identical with the second note of the first entry and so on through all five voices. I don't think I have ever seen another stretto so brilliantly executed.

Well, twenty-four preludes and fugues in all the keys and no two alike. Bach really outdid himself. Just the B major and minor ones to go and I will get to them quite soon.