Alphonsus Johannes Maria Diepenbrock was a Dutch composer, essayist and classicist.
As a composer, he had been completely self-taught from an early age.
He created a musical idiom which, in a highly personal manner, combined 16th-century polyphony with Wagnerian chromaticism, to which in later years was added theimpressionistic refinement that he encountered in Debussy's music.
His predominantly vocal output is distinguished by the high quality of the texts used. Apart from the Ancient Greek dramatists and Latin liturgy, he was inspired by, among others,Goethe, Novalis, Vondel, Brentano, Hölderlin, Heine, Nietzsche, Baudelaire and Verlaine.
As a conductor, he performed many contemporary works, including Gustav Mahler's Fourth Symphony (at the Concertgebouw) as well as works by Fauré and Debussy.
Throughout his life, Diepenbrock continued his interests in the wider cultural sphere, remaining a classics tutor and publishing works on literature, painting, politics, philosophy and religion. Indeed during his lifetime his musical skills were often overlooked. Nonetheless, Diepenbrock was very much a respected figure within musical circles. He counted amongst his friends Mahler, Richard Strauss and Arnold Schoenberg.
Alphons Diepenbrock is related to Cardinal Melchior von Diepenbrock, who was his great uncle, as well as to a branch of the family that immigrated to America in 1879.