← Bach · Well-Tempered Clavier
Prelude 20 in A minor BWV 865
Book I of the Well-Tempered Clavier. Under its figuration, this prelude is 31 chord changes across 28 bars — ranked 6 of 42 by measured difficulty (intermediate) in this survey. Played as block chords, it's a progression you can learn in an afternoon; the piece is that progression wearing sixteenth notes.
Practice this piece → Practice chords → Learn it section by section → Hear the harmony →
How it opens
The first changes are i7 · iiø7 (A) · i7 · v (B) · viiø7/VII · viio7/v (F#) · v · viiø7/iv (B) — and the whole prelude keeps moving at roughly that harmonic pace.
What it leans on
Of 32 labeled changes, the harmonies that do the most work: iiø7 (A) (4×), i7 (2×), i7 (C) (2×), v (B) (1×), viiø7/VII (1×).
Free scores
- Blocked-chord reduction (MusicXML) — the harmony skeleton the player performs
- The prelude as written (MusicXML)