That the National were going to spend six hours repeatedly performing the same song in an art gallery was one thing. A collaboration with Icelandic performance artist Ragnar Kjartansson, A Lot of Sorrow wasn’t intended as a physical endurance test, but a study in the evolving emotional tenor of a work stretched to its limits: National frontman Matt Berninger described its aim as “reaching a different sort of euphoric, mantra-like state.” Releasing the entire performance in a box set composed of nine clear LPs, however, strips away the sad communion of the original Sunday afternoon show, leaving just the listener and approximately 105 iterations of “Sorrow”, spanning six hours, five minutes.

“Sorrow” is the second track on the National’s fifth album, 2010’s High Violet, and one of the few moments of joy on that fraught, scared record. “[It’s] about a person’s love affair with his own sadness,” Berninger has said. “Sadness is not always the worst feeling. Sometimes it’s a really pleasurable thing to be overwhelmed with sadness.” It works beautifully: High Violet marked the point when Berninger started reaching for livelier vocal harmonies, but his helpless, heavy monotone on “Sorrow” is the perfect forlorn center, caught between resisting sanctuary while craving its embrace. The band anchor him there: Bryan Devendorf’s drums are a subtle hiss with a ‘60s girl group dimple, while guitarists Aaron and Bryce Dessner, and bassist Scott Devendorf modulate between three richly thrumming chords.

The luxurious purgatory that Berninger sings about in “Sorrow” is a crucial part of the National’s appeal, which A Lot of Sorrow tests. Every fan wants to believe that they have a special relationship with their favorite band—that they can access something within their work that others could never see—so choosing to engage fully with this kind of project is predicated on the hope that it would induce some kind of transcendent state. (Or, masochism.) But it is a lot—even for a card-carrying National devotee who’s seen them play 25 times in six years, who can’t make it through Alligator without listening to “Baby, We’ll Be Fine” a dozen times straight, or High Violet without lingering on “Lemonworld” for half an hour. I enjoyed an hour of it through headphones on the way home to the suburbs, half-drunk after a Sharon Van Etten show (a very National way to listen to the National), and did the remaining five hours in one go, partially while laying prone on the floor, and soon felt in need of a cold shower.

But A Lot of Sorrow clearly isn’t intended as a consumer item to be placed on your turntable in solemn, linear fashion, which justifies asking what it is for, divorced from its live, physical origins. This release exemplifies pretty much everything that the National’s detractors hate about them, which is rarely just their indulgently sad music. The Ohio-born five-piece are the best dressed straw men in the business, making people bristle at the idea of identifying with the ascendant, middle-class Brooklynite angst of their records. At any rate, it’s a social strata you’d probably have to occupy to afford a copy: sets cost $198 + a hefty postage charge (with all profits benefitting Partners In Health). A week prior to release, the 1500-edition run hadn't sold out yet.

There’s nothing quite as serious as a dead-weight of clear vinyl, yet the existence of A Lot Of Sorrow feels like a cosmic joke, both at the expense of the band’s self-seriousness (an image they’ve been trying to shed with their recent videos and the Mistaken For Strangers documentary), and of those who would accuse them of having made an entire career out of playing the same song over and over. If it weren’t for A Lot Of Sorrow's artistic origins, you could almost interpret it as elegantly weaponized monotony, like Mark Kozelek’s prolific prosaicness, and Aphex Twin apparently dumping his entire hard drive on Soundcloud after releasing his first album in 13 years. You want blood? We got it.

But much as it’s exhausting and unrealistic to absorb in one go, as much a millstone as a symbolic objet d’art, A Lot of Sorrow rewards patience in the most literal fashion. (Another inadvertent joke at the perception that everything the National make is “a grower”…) “I don’t wanna get over you”, Berninger sings in a faint plea every time, an Old Testament pop trope that works as an act of self-preservation and insurance against the responsibility of being the one who has to change. It’s a voluntary slow-death sentence, which he bears stoically throughout the six hours: joking, singing with a mouth full of sandwich halfway through Side O (Kjartansson brought them food and drinks throughout), and saying they’ll have to start over after he coughs during a chorus.

It’s only at the end of Side Q, around the 95th take, that Berninger breaks down. He gasps halfway through “sorrow’s a girl inside my cake” before missing a line and crying, having lost his nerve because he couldn’t see his wife and daughter in the crowd. His live performances are frequently marked by a frightening volatility, and he often openly declares that he needs someone in song, but he’s rarely vulnerable like this. Guitarists Aaron and Bryce Dessner and the band's backing musicians take the lead on vocals (and the crowd joins in), and Bryan Devendorf intuits that he should sit this one out.

Throughout, the unspoken conversation between the band is mesmeric: early on they play more muted versions, like steady long-distance runners. They never break between songs—there’s always that hissing drumbeat or a steady guitar line to guide the transition—and the Dessners constantly experiment with different textures. Sometimes the guitar parts swing like slack machinery; later they tremble with the seismic presence of a Richard Serra sculpture, shriek like birds, and swell drunkenly. I didn’t see the original performance, and had wondered if it might mirror William Basinski’s Disintegration Loops, fading as energy and morale grew dim, but the ceaseless invention here keeps the song alive.

We’re often curious about how a band—and particularly the singer—can remain engaged with the circumstances that originally informed their music night after night. Not that it’s the most apt reference, but perhaps it’s worth remembering the part of Katy Perry’s Part of Me documentary where she emerges beaming on stage seconds after crying over the breakdown of her marriage. After over 100 renditions of “Sorrow”, the National still sound close to its emotional heart, rather than inured to it. No naysayer will be converted by this completely absurd artifact, but it’s a moving manifestation of the relationship that fans have with any band that means anything to them, playing their songs over and over to tempt the point where the magic fades away. A Lot of Sorrow is a strange achievement and vindication. Stay down, champions, stay down.