S9.2. (a) Invention in C, BWV 772, mm. 1–2, followed by varied version BWV 772a; (b) Invention in E minor, BWV 778, mm. 1–4, with additional ornaments (in parentheses) from Gerber’s copy (Hague, Gemeentemuseum, 3831: NMI Kluis F) and (below staff) Friedemann’s little keyboard book