‘Zeg dat ik een ouwe sok ben.’ Alphons Diepenbrock heeft na de voorstelling van Pelléas et Mélisande in de Muntschouwburg van Brussel lust om Claude Debussy te vermoorden

This is a story of rivalries, parallels and deception. In the second half of the year 1893, Alphons Diepenbrock and Claude Debussy independently planned to compose an extensive piece of music to the theatre play Pelléas et Mélisande (1892) by their Belgian peer Maurice Maeterlinck. Of these two composers, it was Diepenbrock who knew Maeterlinck's oeuvre best and admired it the most. His composition, however, never got off the ground. In 1899 Diepenbrock did use a Maeterlinck text, a translation of Novalis' prose text Muss immer der Morgen wiederkommen, while composing his ‘Hymne an die Nacht’ for voice and orchestra. When Diepenbrock finally saw Debussy's opera at the Brussels La Monnaie Theatre in March 1907, its first production abroad after fifty successful performances at the Opéra-Comique in Paris, he became extremely worked up by what he called 'four hours of jellyfish music without muscles or bones'. He felt an urge to kill Debussy, as he wrote to his girlfriend Johanna Jongkindt who then trained as a musician in Paris and actually liked Debussy’s drame lyrique a lot. Diepenbrock’s admiration for Maeterlinck turned into aversion as a result of the performance. Yet despite his bitterness, Diepenbrock embarked on studying Debussy's songs and orchestral scores with extraordinary thoroughness. His letters testify to the importance of what he learned in preparation for the orchestration of two other compositions, Marsyas (1910) and Die Nacht (1911). In his own words, recognition of Debussy's mastery liberated him definitively from Wagnerian influences; he was now open to Nietzsche's credo in Der Fall Wagner (1888) that 'il faut méditerraniser la musique'. For Diepenbrock it was all the more a deception that Debussy, when visiting Amsterdam in February 1914, treated him as quantité négligeable. At the outbreak of the Great War, Diepenbrock's preference for Debussy over Wagner took on a downright ideological character: it coincided with his rejection of German civilization.
Diepenbrock's creative rivalry with Debussy in the period from 1907 to 1912 was mixed with a personal motive. He wanted to seduce his girlfriend (and soon thereafter lover) Johanna Jongkindt with a modern Debussyist idiom. This is most evident in the song ‘En sourdine’ that he composed for her in May 1910, to a text by Verlaine that Debussy had already set to music. Diepenbrock's competitive stand against Debussy has an intriguing precedent in another conflict between composer and librettist, notorious in music history: that of Debussy and Maeterlinck. The latter was confident that the role of Mélisande would go to his lover, operatic soprano Georgette Leblanc, first in 1902 at the premiere of Pelléas et Mélisande at the Paris Opéra-Comique and then in 1907 at the Brussels La Monnaie production. At both occasions he was deceived.