Claude Debussy vacationing in Normandy in 1904, two years after his only opera brought him instant fame.

It may seem a paradox that one of the most influential composers of modern sung theater completed only one opera. “Pelléas et Mélisande” brought French composer Claude Debussy instant fame in 1902…

Skeptical of the theater establishment, relentlessly self-critical and plagued by illness in his final years, Debussy left behind a legacy that musicologists are, to some extent, still working to reconstruct.

Even after a premiere performance, he would continue making adjustments, sometimes to more than one copy of a given score. And he left the majority of his stage works unorchestrated before dying at age 55.

The centennial of the composer’s death this year provides an occasion to revisit the lesser-known corners of his oeuvre. The label Warner Classics in January released the first compilation of Debussy’s complete works, a 33-CD set that includes four premiere recordings of vocal music.

On May 1, the Staatskapelle Berlin, under its music director, Daniel Barenboim, will perform “La Damoiselle Élue,” which Debussy called a “little oratorio,” and the “Trois Ballades de François Villon,” among the few songs he orchestrated himself.

The légende dansée (danced legend) “Khamma,” which had its premiere posthumously in an orchestration by Fauré protégé Charles Koechlin, will be heard at the Philharmonie de Paris on June 9 in a program of the Orchestre de Paris under Fabien Gabel. “Pelléas” also remains in repertoire on the world’s stages, with a new production by Norwegian-German director Stefan Herheim coming up at the Glyndebourne Festival on June 30 and a revival of Ruth Berghaus’ 1991 production at the Staatsoper Berlin from May 27 to June 14.

Barenboim said Debussy, despite being “one of the most important composers in the history of music,” had “yet to really achieve his place in musical life.” He emphasized the composer’s deep connection to both literature and nature: “I think he was fascinated by nature not in the sense of what nature inspires the human being to think about but what nature in itself is.

“Pelléas” represents the culmination of years of exploring the possibilities of vocal music. Debussy wrote about 100 songs, half of which he produced from 1880 to 1886, before he turned 30. The composer was the first to set the poetry of Paul Verlaine, in 1882, while involved in a passionate affair with amateur soprano Marie Vasnier, the wife of a building clerk.

“In this amorous, intellectual and friendly relationship, there is an extraordinary stimulation,” musicologist Denis Herlin, general editor of the “Complete Works of Claude Debussy,” said by phone from Paris. “He finds a means of expression, through poetry and the French language.”

Among the premiere recordings on the Warner Classics collection is “Chanson des brises,” an 1882 work for soprano, female chorus and four-hand piano whose complete score was first reconstructed in 2010. Written for Vasnier, the song further reveals the extent of Debussy’s experimentation with the female voice.

Half the 40 songs that the composer wrote for Vasnier, who had a high enough range to sing coloratura, remained unpublished in his lifetime. He returned to the Verlaine collection “Fêtes galantes” in 1891, however, entirely rewriting two songs with what Herlin said reveals a “heightened sensitivity to poetic structure.”

Around this time, Debussy was working on his first opera commission, “Rodrigue et Chimène,” based on the legend of Spanish nobleman and warrior El Cid. He wrote but never orchestrated as many as three acts, only to desert the project — whose subject matter he declared too traditional — upon discovering Maurice Maeterlinck’s symbolist play “Pelléas et Mélisande.”

“'Pelléas’ was the literary work that inspired him,” Herlin said. “He goes from a vocal style that is very lyrical and passionate to one that is more restrained.”

In the essay “Pourquoi j’ai écrit ‘Pelléas'” (“Why I Wrote ‘Pelléas'”), penned at the request of the manager of the Opéra Comique in 1902 and published posthumously, Debussy cited the need to “obey a law of beauty that seems to be singularly neglected when it comes to dramatic music: the characters of this opera try to sing like real people, not in an arbitrary language made up from worn-out clichés.”

In “Pelléas,” there are no big arias, foreshadowing the operas of Bartok, Berg and other 20th-century composers. His harmonies and inventive instrumentation create an otherworldly realm. As composer Pierre Boulez once remarked, the characters “float” in time and remain “phantoms.”

The preparation of a critical edition for the opera’s orchestral score has yet to completed, however. Of the 37 volumes underway for the “Complete Works of Claude Debussy,” published by Éditions Durand, 21 are currently available.

David A. Grayson, a professor of musicology at the University of Minnesota who is preparing the “Pelléas” volume, explained in an email from Minneapolis that “the objective of the critical edition is to offer Debussy’s last thoughts with respect to the score.”

While the composer’s personal copy remains the primary source, with revisions entered after not only the Paris premiere but also most likely the Brussels and London premieres, Grayson is also taking into account three other annotated scores.

After Maeterlinck, it was Edgar Allan Poe who captured Debussy’s imagination. From 1907 to 1911, and again from 1916 to 1917, a year before the composer died of cancer, he was heavily invested in writing an opera based on “The Fall of the House of Usher,” going through three versions of the libretto based on the translation of Charles Baudelaire.

He also made sketches for “The Devil in the Belfry,” which would have formed a double bill.

“He wanted to arrive at something new with ‘Usher’ and went to great pains,” Herlin said. “But maybe he thought that it resembled ‘Pelléas’ too much.”

Unlike opera composers such as Handel or Wagner, who were not afraid to recycle signature dramatic and musical elements, Debussy was committed to a creative process in which inspiration arose naturally.

“They say some composers can write, regularly, so much music a day,” he told The New York Times in a 1910 interview. “I have forced myself to work when I least feel like it, and I have done things which did not seem bad at the time. I would let those compositions lie for a couple of days. Then I would find that they were only fit for the wastebasket.”

Had Debussy lived longer, however, he might have revisited some of those sketches and fragments. “It’s true that he might have given us remarkable works,” Herlin said. “To the point of the musical avant-garde.”

This article originally appeared in The New York Times.

REBECCA SCHMID © 2018 The New York Times