A contemplative contemporary piano piece reflecting on philosophical themes. It is characterized by sustained harmonic resonance and sparse, lyrical melodic lines.
Focus on maintaining a beautiful singing tone throughout the sustained harmonic textures.
Comparable difficulty and character — good candidates for what to learn next.
"...auf daß wir klug werden" 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.
A typical performance of "...auf daß wir klug werden" lasts about 5 minutes.
"...auf daß wir klug werden" is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Clair de lune by Claude Debussy, Gymnopédie No. 2 by Erik Satie, Ave Maria (The Bells of Rome) by Franz Liszt — see the full similar-pieces list on this page.