Prelude in C minor, BWV 999

The autograph is gone; what survives is the pupil's copy

A large part of Bach's manuscripts did not survive, and this piece is one of the casualties — we can play it today because his pupil Johann Peter Kellner copied it out, and that copy came down to us.

The copy is headed "Prelude in C minor, for lute or harpsichord." That line has kept people arguing for three hundred years: is this a lute piece or a keyboard piece? The figuration suits a plucked instrument very well — the notes fall where a hand can reach them and the voices leave gaps so the resonance can overlap. But the copy itself says a harpsichord will do.

The version most often heard now is on guitar. Guitarists usually move it from C minor to D minor, which lies more comfortably under the hand. So the same piece may have reached you on three instruments in three keys.

The date is equally uncertain; it is usually placed in the Köthen years, 1717 to 1723, though no document proves it.

One gesture, forty-three times, and a different colour each time

There is only one gesture in the whole piece: the left hand places a bass note, the right lays the notes of the chord upward and gathers them back down, once a bar. Forty-three bars means forty-three times.

So what there is to hear is not melody but how the harmony moves. Each bar changes chord, and changes smoothly — often only one or two notes shift while the rest stay put. That sense of having barely moved and yet arrived somewhere else is the substance of the piece.

In the middle the bass begins to descend step by step and the sound darkens with it; near the end the bass stops on one note and holds while the harmony above keeps changing, and the tension gathers from that. The last bars resolve back to C minor.

This suits work or study very well: no melody to pull your attention away, an even volume throughout, and a regular figure that has a settling effect of its own.

Forty-three bars, eleven to thirteen notes in each

Forty-three bars and five hundred and eight sounding notes, in 3/4 and C minor, with no repeats.

The density here is remarkably even: the bar-by-bar note count sits between eleven and thirteen almost without exception. The density does not change; the pitches do.

The range is D2 to C5, a little over three octaves — narrow, because the right-hand figure stays inside one span throughout. The shortest note lasts 0.192 seconds, so it is easy to follow.

The page carries no dynamics, hairpins or pedal marks; Baroque keyboard music was written that way, leaving the light and shade to the player. That is why the same piece can sound so different in different hands.

The difficulty is keeping it from turning into an exercise

This is a level 2 piece here: a simple figure, not much hand movement, playable after a year or two of lessons. But playable and played well are far apart.

First, do not make it even. Forty-three repetitions of one gesture at identical weight and speed is a finger exercise. Follow the harmony instead — push slightly where it tightens, ease where it resolves.

Second, the bass. It is the foundation of every bar and the only thing that marks where the harmony has gone; give it weight rather than the same lightness as the right hand.

Third, the tempo. This performance takes 78 to the quarter. The piece is often played fast, and once it is, the harmonic changes go by too quickly to register — only the fingers are left moving.

Fourth, the pedal. Nothing is written; one change a bar is safe, and where the bass holds one note you can keep it down longer and let the changes above pile up.

We rate this 2 out of 5.

Other pieces that hold one figure all the way

Bach's Prelude in C major, BWV 846, is the most famous example of the same idea — one broken chord a bar, no melody, and it is already on this channel. Heard side by side the difference is plain: BWV 846 is bright, this one is dark.

The Minuet in G and the Invention No. 1 are also here, both at around the same level.