By 1909, Debussy had already composed some of his defining works, including the enthusiastically-received tone poem, Prélude à l’après-midi d’un faune (1894). He had also heard and experienced music outside of the Western Classical tradition.

The fourth prelude of Book I, “Les sons et les parfums tournent dans l’air du soir” (“The sounds and fragrances swirl through the evening air”), takes both its title and inspiration from the poetry of Charles Baudelaire. It is a gentle waltz-like piece in A major with melodies that seem to float as effortlessly as the sounds and fragrances in Baudelaire’s line. Even the harmonies seem tinged with a dusky hue, giving musical evocation to the twilight setting. The prelude is built around three principal ideas and embodies a sort of ternary design, with a brief middle section in the key of A-flat major. It is gentle and subdued, and nowhere is to be found a disturbing phrase or melodic figure. The only true point of contrast within the prelude is a melody in octaves accompanied by a persistent sixteenth-note countermelody. This, however, simply returns us to a variant of the opening melodic motif and the prelude’s serene close.

Des pas sur la neige (Footsteps in the Snow, No. 6) shows Debussy’s unparalleled creativity in using harmonic colours. An omnipresent ostinato runs throughout as a representation, perhaps, of a barren, snow-covered land. Musically, a similar parallel exists: it is a ‘blank’ canvas upon which an array of harmonies are added at different points. These rich sonorities transform the scenery from desolate to ominous to poignant, all before returning to the original key of D minor.

One of the most technically impressive of this first volume is Ce qu’a vu le vent d’ouest (What the West Wind Saw, No. 7) – robust and at times aggressive, this prelude captures the wind’s fury with the sweeping arpeggios, dominant 7th chords, and perhaps surprisingly dense textures – not to mention the massive chords at the conclusion which maximize the instrument’s low register. However furious the character may be, Debussy’s signature innovative style remains present.