Welcome to P&F 20 from WTCI, confirming my theory that Bach reserved some of his most challenging music for the easier key signatures in the WTC. Today’s P&F is in the key of A minor, no flats or sharps. This is the longest fugue with which I am familiar in both books of WTC: six pages. I cannot find a second subject, so remarkably Bach kept the idea moving along with one very long subject of 31 notes (see Easy Key Signature, Funky Fugue for another discussion of a 30 note fugue subject in an easy key signature). Happily, the fugue has plenty of inverted subject statements along the way, a feature that never fails to delight me. It’s a good ride, if lengthy.