Clair de lune

A stroll that became moonlight

Clair de lune is the third of the four pieces in the Suite bergamasque: Prélude, Menuet, Clair de lune and Passepied. Debussy began it around 1890, at twenty-eight, then kept it in a drawer and reworked it for fifteen years. It only appeared in 1905, from the publisher Fromont, by which time Debussy had already written Pelléas et Mélisande.

In its first version, the piece wasn't called Clair de lune but Promenade sentimentale ("sentimental stroll"), like a poem by Paul Verlaine. Just before publication, Debussy renamed it after another Verlaine poem, "Clair de lune" (moonlight), from Fêtes galantes (1869). That poem also gave the suite its name:

Votre âme est un paysage choisi
Que vont charmant masques et bergamasques

("Your soul is a chosen landscape, charmed by masquers and bergamasques.") Debussy loved this poem: he had already set it twice as a song for voice and piano, in 1882 and again in 1891. The Passepied changed its name along the way too: it started out as a Pavane.

Since then, cinema has taken it up, from the Bellagio fountains at the end of Ocean's Eleven to Twilight, and it has become one of the most famous piano pieces.

Three parts, like a breath

The piece is in D-flat major (five flats in the key signature) and in 9/8: three beats, each divided into three eighth notes, a time signature that sways gently. Its 72 bars form three large parts.

• Bars 1 to 26, the theme. The right hand sings in falling thirds and sixths, pianissimo, almost without bass. The ties across the beats blur the bar lines, as if the music were floating. Then the theme gradually comes alive and grows in intensity.
• Bars 27 to 50, the arpeggios. At "Un poco mosso", the left hand starts flowing in arpeggios and a new melody sings above. It's the best-known passage: it rises to a peak, then calms down.
• Bars 51 to 72, the return. The opening theme comes back, carried this time by the arpeggios, then a coda gently fades away (bars 67 to 72).

Harmonically, the three pillar chords of D-flat major are there (D-flat, G-flat, A-flat 7), but Debussy tints them with sevenths, ninths and suspended chords, and slides them in parallel. Just before the end, he even allows himself the most classic progression of all, ii–V–I (E-flat minor 7, A-flat 7, D-flat, bars 64 to 66), which I spot on the map. That map divides the piece into eight-bar phrases, from the introduction to the coda: the three large parts are 1-26, 27-50 and 51-72.

How to approach it

I rate Clair de lune as intermediate: there are few fast notes, but a lot of sound to work on. The difficulty isn't in the fingers, it's in the ear: making one voice sing above the others, dosing the pedal, letting the tempo breathe.

1. Listen while following the three parts: the theme, the arpeggios, the return. With this map in mind, the piece feels much shorter.
2. Understand the harmonies in blocks. Before playing the arpeggios of the second part, play each chord as a block, bar by bar: the left hand learns the shape of the chord, and the arpeggio becomes just a way of unrolling it.
3. In the theme, one voice sings, the other accompanies. The right hand often plays two notes at once: bring out the top one, keep the lower one softer. First count the three beats of three eighth notes to place the ties, then forget them and let it float.
4. The left-hand arpeggios span more than an octave: work on them alone, slowly, thinking about the hand's shifts rather than the notes, with a light thumb. The passages I flag in bars 27-28, 30 and 40 (big leaps in the melody, notes outside the key, many notes) deserve this slow-motion treatment.
5. The pedal changes with each new chord; in the theme, a half pedal is often enough to keep the thirds clear.
6. Don't be afraid of the five flats: D-flat major is played mostly on the black keys, which fall naturally under the fingers. It's often more comfortable than it looks.

The third part takes up the theme of the first: once the first two are learned, you already know almost everything. My plan follows this logic, from the map and the chords to playing it by heart, section by section.