The picture of Gesualdo as an avant-garde visionary is enticing, but in some ways it is anachronistic, ignoring the complex currents of late-Renaissance music. Dinko Fabris, a leading Italian musicologist who accompanied Giancarlo Vesce and me on our visit to the castle, set forth his view of the composer at lunch. “We always want to be surprised by Gesualdo, because of this myth of him as an experimentalist,” Fabris said. “But he was a conservative—as conservative as it was possible to be in this time. Monteverdi was the radical, the new. There is a very curious letter from the poet Guarini, in which he says he prefers Gesualdo to the modern style because he is ‘so far from the hardness of Monteverdi.’ For Guarini, Gesualdo is so nice, so easy! Exactly the opposite of what we now think.”

At a time when younger composers were emphasizing the melodic potential of a solo line—the signature of the early Baroque—Gesualdo revelled in the venerable art of polyphony, in which each voice has equal importance. And, as Susan McClary shows, he clung to the medieval modes, wrenching maximum expression from a language that was on the wane. In “Moro, lasso,” the tenor voice follows the contours of the Aeolian mode while the other voices veer away. Indeed, the movement of the tenor increases the tension of the piece—it “suffers extraordinary stress,” McClary writes, “as though tied to some instrument of torture worked by means of a slowly turning crank.”

Gesualdo’s madrigals are devilishly difficult to perform live, with singers apt to stray from the pitch as the chords wheel about. (Things go easier in the recording studio, where performances can approach perfection through multiple takes: the groups La Venexiana, the Kassiopeia Quintet, and the Concerto Italiano have come particularly close.) I recently watched the New York vocal ensemble Ekmeles rehearse two madrigals from Book V—“Se vi duol il mio duolo” (“If my grief makes you grieve”) and “Mercè grido piangendo” (“Mercy! I cry as I weep”)—in preparation for a concert at Columbia University’s Casa Italiana. At one point, the singers exchanged ideas about what they called “scary” moments, of which there were many. The question of how to articulate a sixteenth-note passage in the first madrigal led to a discussion of its deeper meaning. The tenor Matthew Hensrud commented, “The ‘ardor’ of this—it’s sex, not war.” Jeffrey Gavett, the group’s leader, said, “Yes, except that with Gesualdo the line isn’t exactly clear.”

Gavett had compounded the difficulties by asking the singers to adopt a version of Nicola Vicentino’s intricate tuning system. To modern ears, its harmonies can sound either exceptionally pure or exceptionally weird, or both at once. In Gesualdo’s music, it’s disconcerting enough to hear a G-sharp-major chord after an E-minor one—as happens in “Mercè grido,” in the midst of the line “Would that I might tell you ere I die, ‘I die!’ ” In Ekmeles’s rendition, the moment was made all the more unearthly because the pitches kept shifting underfoot. In modern tuning, the note B-sharp is the same as the note C-natural, but here they diverged slightly, and when the soprano sang them in close proximity the air in the room seemed to ripple, as in a sci-fi movie. Although scholars may question the wisdom of performing the madrigals in this manner, there are so many unknowns around the Prince of Venosa that the idea cannot be ruled out.

The final stage of Gesualdo’s short life was, in some ways, ghastlier than the beginning. If any readers have found the story insufficiently lurid so far, let them now be satisfied. In 1603, two women of his household were tried for sorcery by local authorities, and, under torture, confessed. One of the alleged witches said that she had given the Prince potions of menstrual blood, and that after sexual intercourse with him she had inserted a piece of bread into her vagina and then served it to him in a sauce. (The trial record contains the phrase “soaked with the seed of them both.”) Both women were imprisoned in the castle, which cannot have improved the domestic atmosphere.

The master of the castle was prey to an array of ailments, real or not, and pursued curious remedies. According to one chronicler, Gesualdo was “afflicted by a vast horde of demons which gave him no peace, for many days on end, unless ten or twelve young men, whom he kept specially for the purpose, were to beat him violently three times a day, during which operation he was wont to smile joyfully.”

There is no way to avoid thinking of such episodes when listening to Gesualdo. Perhaps we are meant to. More than a few commentators believe that the last two collections of madrigals—Book V and Book VI, both published in 1611—are autobiographical. Gesualdo possibly wrote the poems himself, or had them written to his specifications. They dwell so often on themes of torment, pain, sadness, and death that, without the incessant variety of the music, they would become monotonous. Gesualdo may have been the first composer in history to write a kind of musical diary.

“I do research in pain,” Giancarlo Vesce said to me. “I work very hard to save animals from pain, but I know the sound of it. In Gesualdo’s madrigals, I can tell that voices are suffering. Gesualdo is the highest expression of pain in music.”

Glenn Watkins, a scholar not inclined toward melodrama, accepts that the madrigals are confessional in nature. Yet he rejects the picture of Gesualdo as a “violent psychopath.” Instead, the composer’s flagellation ritual might be “a manifestation of an exorcism, intended to rid the body of demons.” Watkins views Gesualdo’s late works as recollections of suffering and acts of penitence. Two pieces of circumstantial evidence support this more sympathetic picture. One is a painting called “Il Perdono” (“The Pardon”), which is in the church of Santa Maria delle Grazie in Gesualdo, and shows the Prince kneeling beside Cardinal Borromeo. The other is Gesualdo’s monumental, twenty-seven-part setting of the Responsoria—texts from the Catholic evening services for Maundy Thursday, Good Friday, and Holy Saturday. Those services are known as the Tenebrae, or “shadows”; in the old Catholic rite, candles were extinguished, one by one, until the church was enveloped in darkness.

The Responsoria cycle, also published in 1611, is Gesualdo’s masterpiece, his cathedral of shadows. As Watkins says, it is a Passion in all but name. The tortuous harmonies of the madrigals are put to sacred ends; throughout, Gesualdo displays a madrigalist’s alertness to verbal detail, evoking the betrayal, trial, and Crucifixion of Jesus with a flair that might have caused a scandal if the work had been performed more widely. (It was probably heard only in his private chapel or in Santa Maria delle Grazie.)

“Tristis est anima mea,” the second responsory for Maundy Thursday, begins with desolate, drooping figures that conjure Jesus’ prayer in Gethsemane (“My soul is exceeding sorrowful, even unto death”). It then accelerates into frenzied motion, suggesting the fury of the mob and the flight of Jesus’ disciples. There follows music of profound loneliness, radiant chords punctured by aching dissonances, as Jesus says, “I will go to be sacrificed for you.” The movement from inner to outer landscape, from chromatic counterpoint to block harmonies, humanizes Jesus in a way that calls to mind Caravaggio’s New Testament paintings of the same period, with their collisions of dark and light. Even though Caravaggio renounced Mannerism and heralded the Baroque, the two artists seem close in spirit, not only because of their bloody life stories but also because of the primitive fervor of their religious iconography.

The madrigals are densely packed, hyper-tense; listening to many of them at one sitting can be nerve-racking. The Responsoria—which were splendidly recorded by the Hilliard Ensemble, for ECM, in 1990—unfold in a more open-ended way, joining together into a vast structure that looks ahead to Bach. Some of the sharpest dissonances appear early on, in the passages depicting Jesus’ betrayal, with a piercing semitone clash assigned to Judas. The most disquieting of the pieces is “Omnes amici” (“All my friends have forsaken me”), which lurches from one key area to another, never settling in place for long. One suspects that Gesualdo is identifying with Jesus’ persecution, not least when a particularly stomach-churning progression accompanies the line “And [they have] given Me vinegar to drink.” At the midpoint of the cycle, in “Tenebrae factae sunt” (“Darkness covered the earth”), a sombre stillness descends.