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Prelude No. 1 in C, BWV 846 (WTC I)

J. S. Bach

By Mayank Sanganeria

In C major, this piece is 35 chord changes across 35 bars under the notes on the page — a intermediate-tier piece by our difficulty audit, 73 of 97 in the library, ranked easiest to hardest. Reduced to block chords, that's a progression you can learn in a sitting; the piece you're reading is that progression wearing figuration.

Practice this piece → Practice chords → Learn it section by section → Hear the harmony → Sight-read something new →

What's inside the harmony

Reducing the piece to block chords and labeling every change turns up harmonic phenomena that are easy to miss reading the figuration straight — each one below is also its own corpus-wide census.

• Secondary dominants 7× bar 6: V7/V (C) · bar 10: V7/V · bar 12: viio7/ii (G)
• Chord inversions 17× bar 2: ii7 (C) (third inversion, bass C4) · bar 3: V7 (B) (first inversion, bass B3) · bar 5: vi (C) (first inversion, bass C4)
• Seventh chords 22× bar 2: ii7 (C) — D-minor seventh chord · bar 3: V7 (B) — G-dominant seventh chord · bar 6: V7/V (C) — D-dominant seventh chord
• Pedal points 3× bar 4: C4 held bars 4–6 under I, vi (C), V7/V (C) · bar 24: G2 held bars 24–27 under V7, I (G), ii (G) · bar 29: G2 held bars 29–31 under I (G), ii (G), V7

Free scores

• Blocked-chord reduction (MusicXML) — the harmony skeleton the player performs
• The piece as written (compressed MusicXML)