NEW YORK, NY.- “I feel myself the most unhappy and wretched creature in the world,” Franz Schubert, suffering from syphilis and reeling from professional failures, wrote in March 1824 to his friend, painter Leopold Kupelwieser. Imagine a man, he said, who will never be healthy again, and “whose most brilliant hopes have perished.”

In the same breath, Schubert expressed sorrow over the fate of his attempt at a grand Romantic opera, “Fierrabras,” which had been canceled in Vienna, and that of another stage work, “Die Verschworenen,” which didn’t make it past a private performance. “I seem once again,” Schubert, then 27, wrote in his letter, “to have composed two operas for nothing.”

He wouldn’t return to the genre again. And even after his death in 1828, at 31, when many of his works enjoyed posthumous adulation and were performed widely, none of his theatrical undertakings entered the standard repertoire.

It’s surprising that opera eluded Schubert, who by most counts started about 20 stage works, completed fewer than a dozen and saw the premieres of just two. After all, he wrote some of the most beautiful vocal music in the repertoire: the song cycles “Die Schöne Müllerin” and “Winterreise,” and hundreds of beloved lieder like “Gretchen am Spinnrade” and “Ave Maria.”

And yet the operas remain curiosities better heard than seen, often composed to clumsy librettos and denied the revisions that could have accompanied rehearsals.

Without championing the stage works as worthy of revival on their own, a production at the Opéra Comique in Paris, “L’Autre Voyage,” or “The Other Journey,” is mining their gems. It assembles arias, excerpts from the oratorio “Lazarus” and arrangements of lieder to create a kind of jukebox opera with a story that’s entirely new and entirely, gorgeously true to Schubert.

At its finest, Schubert’s music feels at once like the outpouring of an aching soul and the consoling wisdom of a friend who tells you that the thing you’re feeling, that you’re going through, that you’re afraid of — he feels it, too. “L’Autre Voyage” accomplishes something similar with little vignettes, intimate and universal, mysterious and bittersweet, that overwhelm as they accumulate. It’s the greatest opera that Schubert never wrote.

It’s also not an opera that Schubert ever would have written. His early stage works, like the fantastical “Des Teufels Lustschloss,” were in the vein of popular singspiele (the form of Mozart’s “The Magic Flute”). And his later efforts, especially “Alfonso und Estrella” and “Fierrabras,” were attempts at grand Romanticism. His characters were kings and castle-dwellers, coming from exotic locales or the time of Charlemagne, and his idiom was more fashionable than forward thinking.

Schubert had been trained to write for the stage by Antonio Salieri, beginning in 1812. He was interested in and, under Salieri, encouraged to write across musical forms and genres. The next year, Schubert completed his First Symphony, and quickly began work on “Des Teufels Lustschloss,” which would become his first completed stage work. In March 1814, when he was 17, he presented his teacher with the complete draft; Salieri “read it with delight,” Lorraine Byrne Bodley writes in the recent biography “Schubert: A Musical Wayfarer.”

“Lustschloss” went through a substantial revision, but Schubert’s sense of craft was already present. Beyond lessons, he had learned a lot as an audience member. He had seen Cherubini’s “Médée” and “The Magic Flute,” popular Italian works and both “Iphigénie” operas by Gluck. After attending an 1813 performance of “Iphigénie en Tauride,” according to an account in the collection “Schubert: Memoirs by His Friends,” he was beside himself, saying, “there could be nothing more beautiful in the world.”

Still, “Lustschloss” didn’t make it to the stage. At the time, nothing he wrote did; although Schubert was prolific, his music wouldn’t be performed publicly for several more years, and he wouldn’t be published until the 1820s.

When Schubert gained some popularity, it was as a lieder composer, which set him up for opportunities in the opera house. Two came in quick succession: a singspiel called “Die Zwillingsbrüder” at the Theater am Kärntnertor in Vienna, and the melodrama “Die Zauberharfe,” nearby at Theater an der Wien, where Beethoven’s “Fidelio” had premiered.

Both received just a handful of performances, but, Byrne Bodley writes, “Schubert had his foot in the door of two of Vienna’s most important theaters.” The city’s opera culture, though, was becoming hostile to his style. “As eminent operatic composers dispersed or died, Schubert was caught in the shift of mood,” Byrne Bodley observes. “For a while there came over German opera a sultry stillness, which could offer his reactive mind neither support nor stimulus.”

The house that had premiered “Die Zwillingsbrüder,” Theater am Kärntnertor, was taken over by an impresario from Italy, leading to the resignation of German singers and the advent of a Rossini craze in Vienna. But Byrne Bodley also questions whether Schubert truly had what it takes to make it as an opera composer. He was determined and musically capable, she writes, yet “he lacked the roll-up-your-sleeves practicality and political acumen which Meyerbeer and Donizetti displayed.”

And without performances, Schubert was unable to see the flaws in his stage works. He loved the score for his “Alfonso und Estrella,” but opera, like any music theater, relies on rehearsals and revisions to succeed. It also didn’t help that he was setting poorly written librettos, including by his friend Franz von Schober, who wasn’t practiced in the form.

Circumstances might have been most against Schubert in the case of “Fierrabras.” It had a promising librettist in Josef Kupelwieser — the brother of Leopold, to whom Schubert wrote so despairingly — but had been planned for the now Italian-run Theater am Kärntnertor.

Josef Kupelwieser worked at the theater, but lost his job over an affair. And, shortly after Schubert finished the score for “Fierrabras,” Carl Maria von Weber’s costly “Euryanthe” premiered to little enthusiasm and a lot of boos (including from Schubert); Byrne Bodley writes that it “brought the curtain down on German music theater.” Kupelwieser’s libretto was rejected, and “Fierrabras” was canceled. Schubert didn’t even get paid.

After Schubert’s death, his stage works slowly premiered well into the 20th century. But the reception tended to be the same: good music, bad opera. That is the belief of the brilliant French conductor Raphaël Pichon, who with his instrumental and choral ensemble Pygmalion, has made an art out of Schubert collages — first, with the concept album “Mein Traum” in 2022, and now with “L’Autre Voyage.” (The production travels in March to Opéra de Dijon, with the same performers as in Paris.)

In a program note, Pichon says that in Schubert’s opera catalog, there is “no forgotten masterpiece to revive.” But while going through those works, he added, he came across moments of “almost spiritual meditation,” in which Schubert the composer of “the universal voice” emerges. From those, he and director Silvia Costa assembled “L’Autre Voyage.”

The show begins, though, not with opera but with song — projected text from “Gute Nacht,” the opening of “Winterreise” that gives way to the spare chords of the cycle’s ending, “Der Leiermann.” Hence the title: From the “winter journey” of Schubert comes this “other journey,” one more expansive and lasting a lifetime.

Yet, in Schubertian fashion, its expansiveness is contained within something quite small. “Der Leiermann” is sung by a woman (Siobhan Stagg) at a spinning wheel who lets out a red string that stretches across the stage. From it she cuts a fragment barely more than a foot long.

That red string, the most heavy-handed metaphor in “L’Autre Voyage,” represents one life in the continuum of human existence, that of a male protagonist sung by the elegant baritone Stéphane Degout, who was also heavily featured on “Mein Traum.” Costa is a director who builds images more than scenes, which suits the nonlinear nature of this show. Through those tableaux we see the man happy — at his wedding, or watching his child sing at the piano — but also in unbearable pain. His child dies; he gets older; he sometimes feels as though he, too, is dead.

There can never be resolution to a story like this. But “L’Autre Voyage” suggests there is serenity in realizing that whatever we live through, it is all part of the ever-changing human experience. Along the way, Schubert’s music — arias and lieder, and other excerpts — is strung together with slight alterations, particularly in the arrangements by Robert Percival that, while occasionally anachronistic, maintain the show’s dramatic heft and a sense of consistency.

Works that Schubert wrote for just two musicians or forces as large as an entire orchestra and choir come out sounding nearly, neatly the same. But the moments that stand out most — for their poetry, their lyrical turns of phrase, their sensitive beauty — tend to come in the lieder. And that’s not a bad thing. Schubert might have failed in opera, but he was a master of the art song.

Few lieder composers have approached Schubert in his power to move listeners. And he nudged the form in new directions, especially on the dramatic, evening-length scale of his two song cycles. Those, among his most lasting contributions to music, have taken on a life beyond what he intended. It’s now not unusual to see a staged “Winterreise”; you could call it the greatest opera that Schubert ever wrote.

This article originally appeared in The New York Times.