The Kingdom of Belgium is the only nation on earth that came into being after a night at the opera. In the summer of 1830, Daniel Auber’s “La Muette de Portici”—a flamboyant melodrama first heard in Paris, two years earlier—received a series of performances at the Théâtre Royal de la Monnaie, the venerable opera house of Brussels. The Belgian territories were then under Dutch rule, and the revolutionary overtones of Auber’s opera, which depicts a peasant revolt in seventeenth-century Naples, became associated with local aspirations toward independence. One night, the duet “Amour sacré de la patrie” (“Sacred love of country,” a line taken from the “Marseillaise”) set off a riot both inside and outside the theatre, and the Belgian Revolution began.

In contemporary Belgium, the historic union of Flanders and Wallonia has recently experienced internal tension that could eventually lead to a partition of the Dutch- and French-speaking territories; perhaps not coincidentally, La Monnaie has come under fire. A new coalition government was formed last fall, and it included the New Flemish Alliance, a center-right party with separatist aims, a free-market agenda, and a tendency toward mild anti-immigrant rhetoric. Within days, La Monnaie, which is subsidized by the state, had been told to cut its operating expenses by twenty per cent, and as a result it had to reduce its schedule, causing particular damage to its historically strong dance programming. (Mark Morris’s “L’Allegro, il Penseroso, ed il Moderato” had its première at La Monnaie, in 1988.) For the separatists, La Monnaie and other cultural institutions in Brussels symbolize federalism, and to weaken them is to weaken the Belgian state.

The political calculation is clear: across Europe, parties on both the right and the left are targeting subsidies in the name of populism and austerity. In the long term, though, no one has much to gain from the diminution of storied institutions. La Monnaie is not only one of Europe’s finest companies but also one of its most progressive, and the music world has long looked to it for inspiration. Connoisseurs and tourists alike fill its seats nightly. In Brussels, the de-facto capital of the European Union, the opera stands as a symbol of cosmopolitan culture, and its fate foretells the destiny of the larger order.

Despite the budget crisis, La Monnaie seems determined to maintain its lustrous reputation. In the nineteen-eighties, it prospered under the leadership of the late Gerard Mortier, a Flemish-born administrator with a flair for provocation. Mortier brought Morris to the house and, in 1991, presented the première of John Adams’s “The Death of Klinghoffer.” When Mortier moved on to Salzburg, he was replaced by Bernard Foccroulle, a French-speaking Belgian, who deepened La Monnaie’s commitment to new music and also hosted trendsetting productions of Baroque opera. And when Foccroulle left for the Aix-en-Provence Festival, in 2007, he handed the reins to Peter de Caluwe, another Fleming, who has featured at least one new opera a year, sometimes several.

The novelty this spring was “Penthesilea,” by the fifty-nine-year-old French composer Pascal Dusapin—a formidable, hard-to-classify figure who has drawn on both the convulsive avant-gardism of Iannis Xenakis and the brooding late Romanticism of Sibelius. Dusapin has a close association with La Monnaie; his second opera, a Baroque-tinged monodrama called “Medeamaterial,” had its première there, in 1992, with the great Belgian conductor Philippe Herreweghe presiding. Dusapin, a devotee of German culture, had long been playing with the idea of adapting Heinrich von Kleist’s 1808 verse play, “Penthesilea,” a chaotic, lurid masterpiece of German Romanticism. Dusapin co-wrote the libretto with the Berlin-based playwright Beate Haeckl.

In Greek legend, Penthesilea is the Amazon queen who fights Achilles at Troy. When she is killed by his sword, he is bewitched by the beauty of her corpse. Kleist radically revised the story, making Achilles not the victor but the victim. Penthesilea is torn between her love for Achilles and the warrior code that requires her to conquer him. She can resolve the contradiction only through an act of extreme violence. Setting upon Achilles with dogs, Penthesilea rips him to pieces, and, having done so, delivers one of the more scandalous lines in German literature: “Kissing, biting / It rhymes (Küsse, bisse), and anyone who truly loves from the heart / May take one for the other.” She then kills herself by plunging a dagger into her breast—a dagger that, Kleist says, has somehow been forged from the “cold ore” of her emotions.

Dusapin approaches the material with admirable restraint; the tone of the opera, which unfolds in an unbroken ninety minutes, is grave and meditative, with chantlike lines rising over extended drones and impressionistic washes of timbre. It begins with a lonely modal melody for harp, which is gradually blotted out by a spreading smear of sound in the lower strings and brass. An array of antique instruments—a cimbalom, a type of hammered dulcimer; a sistrum, or sacred Egyptian rattle; various drums and gongs—provide an archaic sonic patina. Although Dusapin occasionally unleashes a Dionysian frenzy in the full orchestra, for the most part the musical action proceeds at a ritual distance. It is a masterly work, yet it is perhaps too coolly controlled for a subject as unhinged as Kleist’s.

The staging is by the veteran French-Lebanese director Pierre Audi, with sets by the Belgian sculptor Berlinde De Bruyckere. The daughter of a butcher, De Bruyckere often evokes damaged and destroyed organic forms—trees, horses, cows, people—and her design for “Penthesilea” simulates the interior of an abattoir; the dominant image is of skins stacked on a pallet. After reading the advance publicity, I was prepared for visceral horror, but Audi and De Bruyckere keep the gore out of sight, creating instead an atmosphere of veiled menace. Evidently, we are meant to equate Penthesilea’s slaughter with the animal trade, although the allegory remains oblique. Like the score, the production seems to be missing some climactic coup de théâtre.

The opening-night performance was vital and exact, with Natascha Petrinsky displaying a molten mezzo voice in the title role and Georg Nigl giving a thuggish thrust to Achilles. Franck Ollu led confidently in the pit. At the curtain call, Dusapin, a gangly man with a shaggy mane of hair, threw his bouquet into the orchestra, recognizing the ultimate source of his music’s smoldering power.

In the Low Countries, the roots of the classical tradition go deep. Renaissance composers of the Franco-Flemish School—including Dufay, Ockeghem, Isaac, Willaert, and Lassus, all of whom seem to have been born within Belgium’s present borders—perfected the art of sacred polyphony, creating works that were large in scale and intricate in design. Building on ideas from England and France, they might be said to have inaugurated composing in the grand manner, setting the stage not only for the masses and passions of Bach but also for the symphonies of Beethoven—who, natives will remind you, was partially of Flemish descent.

In 1970, Herreweghe, a medical student turned choral conductor, founded the Collegium Vocale Gent, which has become one of the world’s supreme early-music groups. Herreweghe’s repertory stretches from the Franco-Flemish masters to Dusapin and other contemporaries, with Bach at the center. After the “Penthesilea” première, I went to Gent to see the Collegium Vocale on its home turf, presenting Bach’s St. John Passion. As with other Herreweghe concerts that are burned into my brain—the St. Matthew Passion, in 2004 and 2012, and the Mass in B Minor, in 2009, all at Alice Tully Hall—the performance had an astonishing, somewhat inexplicable force. At the start, the music-making seemed straightforward, even sedate, with naturalness of phrasing favored over expressive bite. “He’s not doing much,” I said to myself, as the conductor’s hands fluttered through the monumental opening chorus, “Herr, unser Herrscher.” An hour in, I was telling myself, “He has done so much.” The intensification had come through an accumulation of pinpoint gestures: a holding back of the tempo here, a quickening of the pulse there, an increasing weight given to the bass lines in the orchestra, a heightened desperation in the vocal solos. By the end, a towering, enshrouding structure had arisen.