Bach: WTC I, Prelude and Fugue in F# minor

The prelude is one of Bach's very dynamic pieces in running sixteenths with falling 5ths sequences and two cadences on C#. At less than a minute long it provides a foil for the more extended and very different in character fugue. Regarding the fugue, and especially its subject, Joseph Kerman comments:

It is as though having invented the most emotion-drenched subject/countersubject unit he could, Bach wanted to see if he could sustain a fugue with nothing else.

Here is that very unusual subject with its troubling halt on the third note: 

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And the countersubject:

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The sobbing countersubject sounds as if it might have come from an aria in the St. Matthew Passion. Given the expressive strength of this material, Bach doesn't alter it apart from two inversions of the subject in the second half. There is also little modulation except to the dominant. One entry of the subject, in measure 25, is hidden with a melodic variation of the first two notes. Again, he uses the occasional rising fifths sequence. Just before the end and fitted to the long note in the last statement of the subject, Bach inserts a particularly biting harmony: an augmented chord on C# (C#, E#, A = G double-sharp). Both the prelude and fugue end with a tierce de Picardie.

Here is a performance by Sviatoslav Richter with the score:

I use the Richter recordings so much because they are the only ones with the score. There are certainly other fine performances!