This chorale prelude by J.S. Bach, a setting of a penitential hymn, is a profound meditation on human frailty. Its musical distinctiveness lies in its rich contrapuntal texture and deeply expressive harmonic language.
Requires careful attention to inner voices and a somber, reflective interpretation.
Ach, was ist doch unser Leben (BWV 743) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 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.
A typical performance of Ach, was ist doch unser Leben (BWV 743) lasts about 4 minutes.
Ach, was ist doch unser Leben (BWV 743) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.