These prefaces to the Bach-Gesellschaft Ausgabe provide invaluable historical and analytical context for the collected works of Johann Sebastian Bach. They offer insights into the genesis, performance practices, and critical assessment of Bach's compositions, enriching the understanding of his oeuvre.
Requires careful reading and assimilation of historical musicological information.
Bach-Gesellschaft Ausgabe Prefaces (Books 21-30) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
Bach-Gesellschaft Ausgabe Prefaces (Books 21-30) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.