Performing all of the quartets - some nine hours of music in total - has become something of an Everest among string quartets, eclipsed as a classical music spectator sport only by the 14 hours of Wagner's Der Ring des Nibelungen. It's also, frankly, something of an albatross: Beethoven never intended for all of his quartets to be performed together, and would no doubt have thrown a tantrum if someone were to have suggested it to him. Yet, beginning with London's Beethoven Quartet Society in 1845, hundreds of quartets have offered complete Beethoven cycles over the past two centuries.

This season, there are even more Beethoven quartet cycles to be heard than usual, both here and around the world. But, despite having heard numerous performances of individual Beethoven quartets, I've never managed to sit through a complete cycle. (I heard parts of the Emerson Quartet's cycle at Carnegie in 2007 and a 2013 cycle by the Hagen Quartet at the 92nd St. Y.) 

Enter the Danish String Quartet, who made an immediate impression when I first saw them in 2016: "They have a certain hipster appeal, with their spiked hair, scruffy beards and modish-yet-refined attire." The Danes - actually, three Danes (violinists Frederik Øland and Rune Tonsgaard Sørensen and violist Asbjørn Nørgaard) and one Norwegian (cellist Fredrik Schøyen Sjölin) - only reinforced this impression when they arrived at Lincoln Center's Alice Tully Hall on Feb. 7 for the start of what was to be only their second-ever Beethoven cycle, presented by the Chamber Music Society.

In one of their numerous disarming, down-to-earth program notes, the DSQ punctured the aura of reverence writers have lavished upon these quartets over the centuries.

"We put Beethoven on the highest of pedestals and his music is treated as the Ten Commandments: Behold! The Perfection, the Greatness! But, a Beethoven cycle shouldn't be treated as an institution. Rather, the attraction of a Beethoven cycle lies in the imperfections, the raw directness...a fragile humanity."

The DSQ opted to perform the quartets in the order they were written, starting with the first six Op. 18 quartets, which were split evenly over the first two concerts. These early quartets hew closely to the model established by Beethoven's one-time teacher, Haydn, who essentially invented the genre. To be honest, they come across as a bit twee, a bit too eager to please. But, even here, you can hear Beethoven starting to challenge the status quo: the dark brooding of the Adagio in the quartet in F major (No. 1), disrupted by a sudden outburst of emotion; the furious ends to the quartets in G major (No. 2) and C minor (No. 4); the pained wails of "La Malinconia" preceding the otherwise-sunny end to the B-flat major (No. 6). The DSQ's playing was clear, pure, precise, with a total lack of histrionics or dramatic flair. They seemed content to let Beethoven's music speak for itself - rightly so. 

Fast forward to 1806, by which time Beethoven had written the "Eroica" symphony, the 4th piano concerto, and the first version of his opera Fidelio, among other masterpieces. He had also lost much of his hearing, which he had only recently come to terms with. "Let your deafness no longer be a secret - not even in art!" Beethoven wrote on one of his sketches.

Enter Count Razumovsky, a Russian benefactor and amateur musician, who commissioned Beethoven's first string quartets in more than six years. Razumovsky's one request was that Beethoven included a Russian folk tune in each quartet, a request with which Beethoven dutifully complied. Sort of.

Razumovsky got more than he bargained for: the three Op. 59 quartets are longer, more complex, more emotional than anything that had been written before; in his biography Beethoven, Maynard Solomon referred to them as "symphonic quartets." At the time they were written, audiences and musicians alike seemed mystified by them: after playing through the quartet in F major the first time, the Schuppanzigh Quartet were convinced that Beethoven was trying to play a joke on them. Another violinist, Felix Radicati, laughed out loud when he saw the scores, exclaiming: "Surely, these are not music?" To which Beethoven famously retorted: "Oh, they are not for you, but for a later age."

By contemporary standards, and with the hindsight of knowing where Beethoven was headed with his late quartets, the three Razumovsky quartets - which the DSQ played all together on their third program - don't sound particularly radical. Passionate, yes, wide-ranging on the verge of being bipolar, yes, but more or less conventional in structure and form. The F major quartet features an eccentric, jerky "scherzando", where Beethoven seems to be playing a game of cat and mouse, lulling us into submission before chasing with a furious dance. He follows with a pleading, desperate Adagio before ending with a galloping, ironic, too-happy version of the obligatory Russian folk tune. 

The E minor quartet starts off with a pair of emphatic chords, then starts to wander off the reservation with some seriously dissonant chords near the end of the movement. By the end of the deep, soulful Adagio, the audience was so captivated, you could hear a pin drop. The finale, an intense, propulsive Presto, built dramatically from a slow trot to a full gallop.

The C major quartet starts with an offputting, suspenseful introduction, from which Beethoven quickly retreats into a manic, joyous Alllegro (just kidding!) only to return to the opening theme (not kidding :|). The Andante feels pained, full of agony, like a walk through some dark and creepy woods. But, after a polite Menuetto, the quartet ends with the most ecstatic moment in all of Beethoven's quartets: an insanely fast fugue (Allegro molto) that manages to be both light and serious, manic and tightly controlled. In a thrill met with audible gasps from the audience, the DSQ repeated the entire movement as an encore. 

Photo: James Estrin/The New York Times

The next concert felt like a step back to the conventional, with the "Harp" quartet (1809), named for its friendly first movement pizzicato, and the somewhat darker, more agitated "Serioso" quartet (1810), which may or may not have been inspired by a rejected marriage proposal. Having polished off the 5th and 6th symphonies, the Mass in C, and the "Emperor" piano concerto - not to mention living under Napoleon's siege of Vienna - you can hardly blame Beethoven for wanting to chill out for a bit. 

As I sat there listening, I looked around and noticed how familiar everything had become: the hall, the people in the audience, even the DSQ players wearing the same black shirts and pants they'd worn since the first concert. But, the music filling the room was anything but: over the course of four concerts, Beethoven's music had evolved from polite chamber music to bold, challenging works that reinvented every aspect of the string quartet. 

That evolution reached its apotheosis after intermission with the quartet in E-flat major, Op. 127, the first of Beethoven's five so-called "late quartets." By 1825, Beethoven was in his mid-50's and in declining health; having completed such masterpieces as the Missa Solemnis and the 9th Symphony, these five final quartets were to be his last testament in music. Not that they were a retreat by any means: as early as 1806, Beethoven told his publisher, "I am thinking of devoting myself entirely to this type of composition," seeing the string quartet as the ideal vehicle by which to realize his vision of a new musical language. Even now, two centuries later, these quartets sound experimental, visionary. 

The E-flat major quartet starts out somewhat conventionally, with a pleading Maestoso that fades into an easy Allegro. It's the second movement, Adagio, where we "leave unto the unknown", as the DSQ put it in their program note. Nominally a set of variations, below the surface you can feel the surging emotions as it moves from slow and tender, to a slow trot, to a full gallop. From there, it just keeps going and going, extended way beyond anything normal. For nearly twenty minutes, the music just seemed to float as the players barely touched their strings, finally fading away to silence. 

Next was the Scherzando. "Whoa," I wrote in my notebook. "This is some weird shit." Maybe it was just the contrast with the Adagio, but the disjointed phrases and odd chords were jarring and unexpected, like some kind of grotesque dance. Could this all be intentional? I mean, the guy was completely deaf, right? Assuming he knew exactly what he was doing, it felt as if Beethoven was pushing hard against the last vestiges of adherence to form and sound. Perhaps he was screwing with us a little. 

Photo: Tristan Cook

The next program is where Beethoven really broke the mold. Completely throwing convention out the window, the Quartet in A minor unfolds over five movements lasting 45 minutes. It's anchored by the Heiliger Dankgesang ("Holy Song of Thanks") which Beethoven wrote to thank God for sparing him from what he thought might be his final illness. This is the music anyone should want to hear on their sickbed: a pure, sad, gorgeous hymn, full of magic sonorities that raise the hair on your arms. It feels as if it's constantly reaching for something, up to a light, before falling back again. After a last epic struggle, the fever breaks, the sun comes in, and you know that everything's going to be ok. Just an astonishing creation: from what I could tell, there weren't many dry eyes left by the end. A good reminder that Beethoven isn't all Sturm und Drang: he also created some of the most beautiful music ever written. 

If five movements weren't enough, the Quartet in B-flat major, Op. 130 has six, including the infamous Grosse Fugue: a 15 minute beast of strangeness that was so foreign at the time, Beethoven's publisher made him write an alternative ending. (Beethoven subsequently published the Grosse Fugue separately, though most quartets - including the DSQ -  have restored the Grosse Fugue.) This is music of a violent temperament, full of outbursts and wild dissonances; you can just imagine Beethoven stomping through his flat as he shouted the "melody." It's as avant as you can get - and it was written nearly 200 years ago. I can only imagine what Haydn would have said if he'd lived to hear it.

Beethoven ups the ante to seven movements in the C-sharp minor quartet, Op. 131, which began the final concert on Feb. 18. This was the quartet Beethoven declared to be his best, having spent the better part of a year (and 600 pages of sketches) on it. The seven movements are played without pause, starting with a slow, mournful Adagio that ends with an extraordinary consonance, to a youthful Allegro, to an Andante full of tenderness, to a superfast Scherzo full of pizzicato with a deliberately messy ending, to the final dramatic Allegro, filled with intense emotion. There is honestly just too much to unpack from this supremely constructed quartet to go through here; suffice it to say, the DSQ played it flawlessly, nailing every last detail with no visible seams. 

Before the last quartet, the violist, Asbjørn Nørgaard, paused to thank the audience and the Chamber Music Society for allowing them to take this journey with us. 

"Even here in the Capital of the World, there's something special about sharing this music as a communal experience, hearing it all live together." 

Beethoven's final quartet, the Op. 135 in F major, is a return to (relative) normalcy, four movements lasting a reasonable length. Throughout, it's less elegiac than laughing, a sort of gallows humor as Beethoven surely knew he must be nearing his end on this mortal coil. Inscribed above the score's final movement ("The Hard-Won Resolution"), is a phrase familiar to anyone who's read Milan Kundera's The Unbearable Lightness of Being:

"Muss es sein? Es muss sein!" ("Must it be? It must be!)

After a light Allegretto and a fiery Vivace, the Lento assai movement is slow and mournful, but feels more accepting than sad - a beautiful farewell fading gracefully away. The quartet ends with a brief struggle, followed by an upbeat Allegro that almost feels like a celebration. 

And, with that, it was all over. I hung around afterward to meet the quartet at the CD table, where they told me they were flying back to Copenhagen the next day, but not before heading out and having a few drinks on their last night in New York. Well-deserved, guys.

If you missed this cycle, Paris' Quatuor Ébène will be doing it all over again starting on 4/17 at Carnegie's Zankel Hall, one of seven cycles they'll be performing all around the world this year. With tickets starting at $54 per concert, seeing the entire cycle is no small investment. But, even if it's not this year, you owe it to yourself to take this journey at least once. I know I'm glad I did.

More pics here.