How do we play early music on a late piano?

My first experience playing the music of CPE Bach was not as a pianist but as a violinist, leading a high school orchestra in the extraordinary last movement of the D minor flute concerto. I was immediately struck by its originality and raw emotion, and concluded that had his positioning in the timeline of music history been a bit more auspicious, his place would have been guaranteed in the firmament of composers (something I still believe today).

The work I discuss here is a lot less conventional than the D minor flute concerto, but it still shares the same sense of raw and uninhibited expression. The F major Fantasia for keyboard is part of a collection of sonatas, fantasias, and rondos written for “connoisseurs and lovers” (Kenner und Liebhaber). It is more fantasy-like than most great fantasies written for the piano as it is truly and entirely improvisatory. Except for a middle section in C major, it has no barlines, making metric division merely implied rather than written out. Its harmonic twists and turns are entirely unpredictable, and are in fact sometimes rough and uncouth, as he breaks the conventions of harmonic transition (something he did quite often).

Here is a performance of this highly unusual Fantasia: