Debussy couldn’t quite understand how Chopin could be so consistently and outstandingly original without recourse to a much larger palette. Debussy’s own Preludes were his attempt to find this musical ‘everything’ in a single instrument, yet he was too good at conjuring up the most magical sonorities in an orchestra, or the most beautiful melody from a line of poetry, to constrain himself as Chopin did. (Neither were Chopin’s strong suits.) So he wrote one of the most important operas of the twentieth century – Pelléas et Mélisande (1893–1902) – and orchestral works such as Prélude à l’après-midi d’un faune (1894), which set the scene for that magician Stravinsky and his enormous bag of tricks. Solo piano works remained with him until the very end, however – with their wonderful improvisatory feel and implicit disdain for some of the formal arguments of nineteenth-century music – as though he was showing that Debussy could have lived up to Chopin’s great example if he had just put his mind to it.

It is hardly inevitable that Stephen Walsh would tackle Debussy after writing so comprehensively and authoritatively on Stravinsky, though it makes perfect sense. It’s not simply that each composer revolutionised the shape and sound of music written for orchestra, or that each blossomed in the hothouse climate of Paris in the last decades of the nineteenth century and the first ones of the next. It’s also that Debussy’s death in 1918 at age fifty-five deprived us of a slew of works – and not only those such as the operatic adaptation of Le Martyre de Saint Sébastien, which remained unrealised on his death. Stravinsky partly makes up for our loss while simultaneously taking the story (perhaps a story is more accurate) of twentieth-century musical modernism that much farther down the road.

It was Pierre Boulez who declared that Debussy was at the core of this story. ‘Should we then set up a Debussy–Cézanne–Mallarmé axis as the root of all modernism?’ he asked after World War II. This is Walsh’s argument, that Debussy saw it as his duty to break with the expectations and conventions of nineteenth-century music-making. And so the Debussy who emerges from these pages is smart, witty, innovative, largely unfussed by social mores – at least as they touch on his messy private life – and mistrustful of authority, especially the censorious and self-important Paris Conservatoire, to my ear an over-egged villain in this particular pudding. He is thoughtful, too, writing to Stravinsky during the Great War that the Germans were attempting to destroy French art alongside their land. In counterpoint, Debussy the critic gets welcome attention: Berlioz was ‘always the favourite musician of those who knew little about music’; Richard Strauss is ‘a great figure [with] the frank and decisive appeal of those great explorers who walk among savage tribes with a smile on their lips’; Stravinsky’s The Rite of Spring is ‘savage music with all modern conveniences’.

Claude Debussy, portrait, June 1908 (photo by Otto Wegener/Wikimedia Commons)Walsh skilfully zigzags between life and work, in prose that is both vibrant and stylish, though not free of cliché: lyrics fit Debussy’s musical requirements ‘like a glove’; Debussy could write particular types of accompaniments ‘till the cows came home’; certain works ‘cut a great deal more ice’ than others. These clichés are a by-product of Walsh’s determination to ensnare a broader readership than that of a typical musicological monograph, and he is admirably free of jargon as a consequence. ‘A classical piece is like a well-told story,’ he writes of Ariettes oubliées, Debussy’s still, exquisite cycle of 1887, ‘with a number of narrative threads, locations and characters that must all be tied up and reconciled in a coherent way. These Debussy songs are more like pictures, images drawn in notes and intensified by the repetition of brief, self-contained units . . .’ Nice. He writes well of the ‘rogue overtones’ of the bells in ‘La Cathédrale engloutie’ and the ‘swell of the ocean as seen and heard, the boom of waves on rock’ buttressing the Prelude, though strangely he does not reference Howat’s pioneering study of the piece and his conclusion that for a hundred years or so we’ve all been playing it at half speed. He writes convincingly about rhetorical stresses on the wrong syllables in French conversation and Debussy’s incorporation of this technique into his word setting for dramatic effect. And he tersely explains the difference between Impressionism and Symbolism – the first relating subject to technique, the second subject to meaning.

Yet Paris is largely missing in action: Haussmann’s magnificent boulevards and his wholesale construction of the most bourgeois capital city in Europe do not really emerge. There are some odd repetitions, too, which survived the editing: Mme Wilson-Pelouze attends the first Bayreuth Festival in 1876 and does so again twenty pages later; Debussy enters the Prix de Rome for the first time in 1882 without progressing beyond the first round, and does so again pretty smartly with the same result. Occasionally, Walsh is just wrong: equal temperament is not ‘the compromise tuning demonstrated in the Well-Tempered Clavier’ (the clue is in Bach’s title). Yet mostly Walsh corrals his angels and monsters – Gabriele D’Annuzio, Wagner, Diaghilev, Debussy himself among them – with skill and affection. If, Walsh concludes, a hundred years after his death, we end up judging Debussy harshly for the way he treated the people in his life, – ‘the teachers he mocked, the women he ruined, the friends he lied to and sponged off’ – we at least have the music as an explanation for his behaviour, which is no small compensation after all.