Prelude and Fugue, for keyboard No. 18 in G sharp minor, BWV 887 (BC L121) (WTC II/18)

Veering from the expected A flat minor, this pair of pieces employs the closely related, enharmonic key of G sharp minor. The prelude, with its simple bass line supporting melodic filigree, uncharacteristically features contrasting dynamic markings and looks ahead to the galant style favored by the generation of Bach's sons. The three-voice fugue is something of a gigue, the wavering subject's voices entering in descending order. Eventually, a new subject of chromatically descending notes works its way into all three voices, and ultimately joins forces with the original subject.