Bach's chorale prelude 'Ach Herr, mich armen Sünder' (BWV 135) is a deeply moving meditation on sin and redemption, transforming the familiar chorale into a rich polyphonic tapestry. Its musical distinction lies in its expressive melodic lines and intricate contrapuntal development.
Requires a sensitive touch and careful voicing to bring out the individual contrapuntal lines and the overall expressive arc.
Ach Herr, mich armen Sünder (BWV 135) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Ach Herr, mich armen Sünder (BWV 135) lasts about 5 minutes.
Ach Herr, mich armen Sünder (BWV 135) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.