With a libretto by Szymanowski and the Polish writer Jaroslaw Iwaszkiewicz, “King Roger” finds a wrenchingly personal way to explore a timeless theme prone to cliché: the duality of human nature, or the struggle to balance reason and duty with erotic ecstasy. Roger is a king in 12th-century Sicily, burdened by responsibilities and grown inexplicably cool to his lovely wife, Roxana.

A stranger comes to town in the person of a charismatic shepherd who espouses sensual fulfillment and promises to free those who are living in emotional chains. The archbishop and his followers demand that the shepherd be killed. But the people, including Roxana, fall under this visitor’s Dionysian spell. Tormented by doubt and seized with a confusing desire for the shepherd, the king is thrown into a life-defining crisis.

It is hard to imagine that the Santa Fe Opera would have presented “King Roger,” had it not lined up the dynamic Polish baritone Mariusz Kwiecien to sing the title role. For some years now Mr. Kwiecien has been treating Mozart’s Don Giovanni as his calling card role with international houses, including the Metropolitan Opera. Though an intense and alluring Giovanni, Mr. Kwiecien has lots of competition.

But he owns the role of King Roger, which he first sang with the Paris National Opera in 2009. I missed that production, but reviews and videos give the impression of a wild, modern, erotic interpretation. The Santa Fe production, directed by Stephen Wadsworth, is disappointingly tame. Still, he deserves some credit for Mr. Kwiecien’s courageous performance.

The handsome Mr. Kwiecien exudes authority as the king, which makes his anguish even more moving when the shepherd rattles him. Singing in his native Polish, he can highlight the innate qualities of his impressive voice: the dark colorings, earthy textures and muscular delivery. In a video interview made for this production, Mr. Kwiecien is insightful about the music and themes of “King Roger.” He even has a natural affinity, he says, for Szymanowski’s harmony, which he describes as “close to the mountains of Krakow, the harmony I have in my ears.”

And what harmony it is. Szymanowski, who died in 1937 at the age of 54, is finally gaining recognition, not just as the father of 20th-century Polish composition, but also as a modernist on his own terms. As a young man, Szymanowski absorbed the music of Germany, France and Russia. But his trips to southern Italy, with its remnants of ancient Greek culture, and to northern Africa, proved formative.

Szymanowski saw the Mediterranean region as a melting pot of cultures and religions. “King Roger” has a melting-pot score, urgent and quickly paced, lasting about 80 minutes. Hints of Wagner, Strauss, Debussy and Scriabin are also charged with Middle Eastern sensuality. The conductor Evan Rogister had a great night, performing the three-act work without an intermission. He drew nuanced and voluptuous playing from the Santa Fe Opera orchestra.

“King Roger” was a work of brave personal exploration for Szymanowski, a homosexual who wrote homoerotic love poems and a philosophical novel intended for his friends. In a program note Mr. Wadsworth writes that the “operatic Roger resembles Szymanowski himself and wanders an inner landscape of personal and philosophical crisis.”

The opera opens with an entrancing choral scene, beautifully sung here, set in a Byzantine church in Sicily. The scenic designer Thomas Lynch depicts the scene very simply, with just golden murals, rows of wood chairs and a glittering throne for the king. Nuns, clerics and noblemen in severe black garments enter, along with people wearing exotic northern African and Middle Eastern costumes (designed by Ann Hould-Ward). But King Roger, looking like a stand-in for Szymanowski, is dressed in a three-piece gray suit, though he wears a crown and wraps himself, almost protectively, in a radiant robe.

 In presenting “King Roger” as both a mythic tale and a personal drama, Mr. Wadsworth’s balancing act goes awry with the arrival of the shepherd, played by the tenor William Burden. In the libretto, Edrisi, an Arab scholar who is the king’s counselor, describes him as a “youth with copper curls” wearing a goatskin, with eyes like stars and a smile full of mystery. He is meant to be so dazzling that anyone — man or woman, gay or straight —would be smitten.

When asked what the god he worships is like, the shepherd answers, “He is as beautiful as I am.” Though a good-looking and gifted actor, Mr. Burden makes a very mature and rustic shepherd. In his ragtag costume, he could be someone that Maria from “The Sound of Music” would encounter on a mountain path.

At times Mr. Burden is fatherly and comforting in his interactions with the king, like a coach trying to encourage a youth to get out there and live, live, live. That may be a fair, if rather dull, way to conceive the character. But in the final act the shepherd appears once more and, either in reality or in Roger’s hallucination, is revealed to be Dionysus. Unfortunately, Mr. Burden was made up to look like Papageno, in leaf-covered pants, frumpy coat and laurel crown.

In this astonishing scene the king goes over to the wild side and partakes of Dionysian revels. Mr. Burden’s Dionysus is merely an enabler, watching while some buff dancers engage the king in erotic gyrations and hoist him on their shoulders. Mr. Burden’s singing is honest, expressive and clear, though he sometimes sounds strained on sustained notes in his upper register.

The soprano Erin Morley, an endearing Roxana, sings with lovely, penetrating sound, capturing the wistful tenderness of the beautiful queen. Aggrieved by her husband’s coldness, she is easy prey for the pagan shepherd. The tenor Dennis Petersen brings an ardent voice and a grave demeanor to Edrisi.

“King Roger” poses a dangerous question: What would we do if we could do anything? Perhaps it would be too easy for a director to turn loose a lot of scantily clad choristers for the dances of ecstasy. Mr. Wadsworth presents real people under temptation. Still, his production is just not dangerous enough.

“King Roger” runs through Aug. 14 at the Santa Fe Opera; (505) 986-5900, santafeopera.org.