Ephemera Op. 21 is a reflective work that uses dissonant clusters to evoke a sense of impermanence. It is distinct for its experimental approach to piano resonance and sustain.
At Henle 4 this is an intermediate piece that expects secure technique and real attention to phrasing. The main demands: chord voicing — bringing out one note inside a handful of others; careful pedaling — clarity depends on the foot as much as the fingers; and big chords that need weight without harshness.
Management of sympathetic vibrations through pedal control is essential for the intended sonority.
Comparable difficulty and character — good candidates for what to learn next.
A level or two down with the same spirit — ideal if this piece is still out of reach.
Where this piece's skills lead: slightly harder works making similar technical demands.
Ephemera (Op.21) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
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 Ephemera (Op.21) lasts about 4 minutes.
Ephemera (Op.21) 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 Gymnopédie No. 1 by Erik Satie, La cathédrale engloutie by Claude Debussy, Gymnopédie No. 3 by Erik Satie — see the full similar-pieces list on this page.