“AS-COL-TA!” (Listen!) is the imperative repeated throughout Luigi Nono’s Prometeo. The composer subtitled his magnum opus, which premiered in 1985, “tragedia dell’ascolto”, a tragedy of listening. It could also be described as a challenge to listen. Nono, Italian Resistance fighter, left-wing political activist, thinker and traveller wanted to change our experience of listening to music by making sound itself the dramaturgical skein of his “opera”.

Prometeo is a colossal undertaking requiring specialist performers. The composer stipulated the positioning of the singers and instrumentalists around the audience, an architecture inspired by the cori spezzati, separated choirs singing in opposite lofts, of late Renaissance church music. For the Nono minifestival within the Holland Festival, the huge gasholder at the Westergasfabriek, a former coal gas plant, was transformed into the specified cathedral of sound. The two conductors, Ingo Metzmacher and Matilda Hofman, stood on a low platform on the north side, with the Schola Heidelberg choir and one orchestral grouping from the combined SWR Baden-Baden and Freiburg Symphony Orchestra and SWR Experimental Studio. The other three orchestral groupings, solo singers, and two speakers, Caroline Chaniolleau and Mathias Jung, were scattered on a three-level scaffolding construction on the other three sides. All performers were miked to enable live electronic manipulation, coordinated by André Richard. Once the performance started, it was tempting to look around trying to trace where each sound was coming from, which proved disorientating. A phrase could originate from a bassoon player behind you, but come at you through the loudspeakers on the left.

The libretto, by philosopher Massimo Cacciari, is based on sources related to the myth of Prometheus, the immortal Titan who stole fire from the gods and was chained to a rock where an eagle daily devoured his perpetually regenerating liver. The nine sections contain texts by, among others, Aeschylus, Goethe, Hölderlin, and Walter Benjamin, a German philosopher who committed suicide while fleeing from the Nazis, and who refused to view history as a continuum of progress. However, the words are not discernable as ancient Greek or German, because Nono deconstructs them into their phonetic components, echoing, kneading and stretching the fragments and moving them at different speeds. We can occasionally make out a whole word: “Gaia”, “Prometheus”, “silence”, “eternal”, but most of the time we hear elongated vowels (EEEE-OOOO). Sometimes only the consonants are articulated. The short phrases lurch and flit in and out of silence. Syllables linger and overlap, or evaporate suddenly. Similarly, musical elements are disentangled and rewoven into elusive composites. A single tone in a chord will persevere, forking into another chord coming from the opposite direction.

Despite the electronic manipulation, the sound is organic and oscillates with emotion. Nono was a key figure of the 1950s avant-garde, but adopted a flexible approach to the restrictions of twelve-tone serialism, spearheaded by Arnold Schoenberg, who became his father-in-law. Moreover, his political activism kept his compositions centred on the human plight. In Prometeo the singers balance brittle polyphonic arcs of luminous sound, while the orchestra interjects with dissonant, microtonal music, voicing the snorting and flaring of beasts, the shuffle of reptiles, the very creaking and crimping of the earth. The effect is one of cries and groans rebounding in primordial chasms, whispers and trickles in caves, echoes intersecting across expanses of water. The coils of sounds and silences never stop moving, sometimes converging to suspend time, sometimes swirling to accelerate it.

The choral writing, based on simple intervals (many 4ths and 5ths), contains ungraspably beautiful passages and culminates in the haunting final section, “Stasimo Secondo”, reminiscent of an exiting Greek chorus. Like the choir, a secure and impressive Schola Heidelberg, the five soloists paint tone pictures using various voice production techniques, including singing into their cupped hands. “We vanish, we fall/ the suffering humans/ blind from one/ hour to another/ like water thrown/ from cliff to cliff/ for years into the unknown depths”. Hölderlin’s verses from “Hyperion’s Song of Fate”, set in “Isola Seconda”, are too refracted to make out, but are depicted by splashes of high voices tossing about on serrated sound columns rising from flute and clarinet. Blending marvellously together, each soloist showed a distinct vocal colour. Susanna Andersson’s seraphic soprano evoked open skies and bird flight and contralto Noa Frenkel the deep, fecund earth. Mezzo-sopranos Christina Daletska and Els Janssens-Vanmunster were the ember-toned middle range and Marcus Francke produced incorporeal tenor sounds.

Prometeo fascinates with its inventiveness, seduces with its beauty, but also intentionally frustrates by denying the intellect direct meaning. Nono asks the listener to abandon understanding through semantics in favour of exploring through perception. Anyone interested in post-World War II music, given the opportunity to hear this work live, should set aside all preconceptions about opera, serialism, singing, words, and meaning, take up the challenge and go “Listen!”.