Under the direction of composer Heinz Holliger, and staged by the house’s own intendant, Andreas Homoki, the new Lunea sets its own rules. Rather than building a continuous plot thread, any chronological sequence of events and their three-dimensional settings are deliberately abandoned. Instead, the opera unfolds in 23 so-called “pages” – visions, flashes of insight and fantasy images – that shed light on texts, figures and moments of the Biedermeier poet Nikolaus Lenau’s life. In short, the collective “pages” are as hard to assign to logic as it is to pin down a dream.

That said, the start mirrors the poet’s real fate: the Austrian Lenau suffered a stroke at middle age – “a crack across my face” as he describes it – and was confined to a mental institution thereafter, which clearly affected his sensitivity and damaged his perception. Händl Klaus’ spare libretto retains many of Lenau’s almost Dada-like formulations, such as “Man is a sandpiper by the sea of eternity”. But just as Lenau did after the stroke, the Lunea protagonists distort and rearrange words throughout the work.

Likewise, typical of the score is a recurrent “reversal” device: notations played forward and backward, just as the scenic narrative moves forward, then backward, in time. What’s more, the music is often hallmarked by inexplicable, mesmerizing sounds. In a pre-première rehearsal, Holliger revealed that he was happy if listeners couldn’t always determine “how the sounds were made”. That said, their variety is a virtual feast.

Much of Lunea’s resonance, though, is attributable to Holliger’s choice of principal singers, both of whom he has worked with here before. In 2011, Christian Gerhaher premiered the composer’s song cycle Lunea, which would serve as the nucleus of this expanded new work. Now as Lenau again, Gerhaher sang a brilliant baritone around the tumbling musical fragments, quirky intervals and twisted emotions his role demanded. In rehearsal, he complained that in one instance, the scripted stretch from one very high to another very low note in short order was painful, and Holliger had him adapt it to what would work. If Gerharer can’t sing the role, namely, probably nobody can.

Juliane Banse – who sang the lead in Holliger’s 1998 Zurich Schneewittchen (Snow White) – was Sophie von Löwenthal, Lenau’s beloved. In a stellar performance, the German soprano gave silvery polish to that critical role, which asks for the widest possible range of rhythm, color and vocal expression. Among the other accomplished principals, Ivan Ludlow, Annette Schönmüller and Federico Ituarte all sang handsomely. Sarah Maria Sun carried two roles admirably, both of them being women Lenau courted and disappointed, although I found her highest soprano voice grating and steely.

Intendant Andreas Homoki staged “pages” as diverse as from the definition of intimacy to recollections of the poet’s mother, from the rejection of an illegitimate child to Lenau’s attempt to immigrate to the United States. In 1832, Lenau was disillusioned with the “greedy people and shopkeepers” he found across the ocean, calling the fledgling America “a nation that has no nightingale”. Interestingly, the 23rd “page” (of bird calls and twittering) was ultimately excluded. Holliger apparently thought it would break up an almost godly sense of the previous page’s sounds, among other effects, of soft breezes passing through ice-glittery branches.

Frank Philipp Schlössmann’s set was consistently simple, punctuated only intermittently by a few chairs or a settee, making for an uncluttered confrontation with the characters. Franck Evin’s lighting also served the haunting drama, exposing personal foibles by creating hard contours and casting shadows on the side-walls.

Finally, a choir of twelve Basler Madrigalisten under Raphael Immoos’ direction took us skillfully through the score’s otherworldly sounds. The dissonant harmonies and variable tempi posed little problem, and their movements seemed equally assured, despite the silk bells of the women’s voluminous skirts. Lucky, because Klaus Bruns’ stunning Biedermeier costumes capitalized on his materials’ effects: the group in a circle, leaning in towards one another, for example, resembled a fleshy white peony in full bloom. And the house’s Philharmonia Zürich orchestra – here with its superb concertmaster Hanna Weinmeister as soloist and Matthias Würsch’s rare cimbalom – embraced the complex score so well that, at curtain, the composer simply beamed like a Cheshire Cat.

Given that this music stretches the definition of identifiable sounds and conventional harmonies, Lunea will be a challenge for those who prefer Mozart or Verdi. Further, the sustained “stuck stress” of Lenau’s insanity translates to little action on stage in the traditional sense. Nonetheless, with Heinz Holliger and Andreas Homoki both pushing the limits of their genres, their cooperation makes this one of the season’s most unforgettable, if pointedly cerebral, musical encounters. Indeed, Lunea may well set the stage for the next generation of opera, whether or not you agree to call it by that name.