This Prelude and Fugue has, as you can see, a considerable number of sharps; in fact it has seven, moving every note of the scale up a semitone.  In ‘just’ tuning the results of performing in such an exotic key (or, even worse, F#!) would have been, to say the least, rather unpleasant. But for Bach – set on demonstrating that his well-tempered keyboard could be effective in no matter how many sharps or flats – the far reaches of the tonal system held no such terrors.

Course materials:

Here are some visual and audio aids for the third prelude and fugue in C#  (if you want to access them off-line, they can be downloaded from the box on the right):

Prelude C# analysis

Fugue C#

… and below to help deal with intervals, modulations, etc., are more general items that most of you will have seen before:

Keyboard

Cycle of 5ths

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