There are a couple ways you can divide up R.E.M.’s career. Considering they are a band that released music for just about 30 years, almost fitting within three specific decades, you can almost look at their work in three acts. There are the formative and iconic ’80s college-rock days, in which R.E.M. became one of the acts that laid the foundation for indie as we know it. From the very late ’80s through much of the ’90s, they became Alt-Nation era pop stars. Then there were the searching years, from the late ’90s through to their dissolution in 2011, a legacy name bending their sound and ethos and eventually returning home before saying goodbye.

Even within that, there are counterpoints: Document was doing something different than Murmur and Reckoning, Monster was doing something different than Automatic For The People, Accelerate was doing something different than Around The Sun. Mostly, it is a legible way to look back, and their fanbase often divides along lines related to these eras — the original fans who never embraced R.E.M.’s greater fame and notoriety in the ’90s, the kids who got turned on to them by way of those same ’90s mega-hits, acolytes who see worth in every corner of what this band released.

But there is another way to split their career. In 1997, just past the mid-point of R.E.M.’s lifespan, their drummer Bill Berry left the band. Over time, this has become the definitive approach in partitioning R.E.M.’s catalog. No matter the diversity and growth that characterize each era, there is no getting away from these two distinct halves, with Berry and without. His departure almost broke the band, and there may still be fans out there who argue it should have. But they continued on, soldiered on — releasing another five albums before finally quitting almost 15 years later. The first and perhaps most crucial of those albums, Up, arrived 20 years ago this past weekend.

The list of bands in rock history in which the drummer quitting could even barely necessitate appraisals of where to go from here, considerations of whether the band should continue, is a short one. There are plenty of instances in which a drummer is pivotal to the band’s sound, and they might change afterwards. But, stereotypically, it isn’t something that makes a band collapse. And that’s just speaking about the group and their music; if you are to compile the list of bands in which the drummer leaving could mar a whole decade-plus phase of their career for their listeners, you could probably count them on one hand.

R.E.M. were one of those bands that was always just those four guys. From the start, in the studio, on the road — they occasionally let other voices in, but there was never any doubt that you needed these four personalities and talents to create the specific kind of alchemy the band had achieved. So they are one of the rare instances where, if one part of the equation is removed, the whole enterprise would seemingly fall apart. You had Stipe’s gravel voice and enigmatic lyrics and art-kid charisma, Mike Mills’ harmonies and nimble basslines, Peter Buck’s heavily influential guitar cascades, and Berry holding it all together. So what happened when the story went on missing one of them? Up was seemingly the answer.

Up wasn’t like anything R.E.M. had released before. (And, mostly, it isn’t quite like anything they released after, either.) With everything post-1997 existing in the long narrative shadow of Berry’s departure, it’s tempting to regard the significant left-turn of Up as a direct reaction to the band having lost a founding member and balancing force. In reality, the chronology and details don’t support that. Before Berry left, R.E.M. were already discussing the follow-up to their sprawling, exploratory 1996 release New Adventures In Hi-Fi as a potential new direction. And when Berry finally informed the whole band of his decision, it was just as rehearsals were beginning ahead of Up’s recording. They had the demos and a plan for a new kind of R.E.M. album. Nevertheless, Berry’s departure hung over the album functionally and thematically.

R.E.M. were one of those bands that didn’t just undergo a couple superficial stylistic evolutions over the course of their career — still doing their thing, but now the guitars sound different, now they use synthesizers. They are of a rare breed that upended their songwriting approach several times over and were successful at nearly every turn. Through the ’80s, you could hear traces of folk and pop making their presence known louder and louder in R.E.M.’s music, before blossoming into different versions of the band on albums like Out Of Time and Automatic. Prior to Up, there were some other curveballs, like Monster’s grunge-glam denoting R.E.M.’s foray into the ’90s alt-rock culture they’d helped birth.

But Monster was at least still a rock album, and there was almost no precedent for Up in R.E.M.’s catalog. Relying primarily on drum machines and loops, on synthesizers and alternatingly simmering and dreamlike electronic textures, it found the aging indie-rock godheads delving into the late ’90s electronica moment. It was a move common at the time, from U2’s Pop to Smashing Pumpkins’ Adore and eventually Radiohead’s Kid A. (Though not from the rock world, Madonna’s Ray Of Light was another installment in this late ’90s trend.) In what was still seen as a radical reinvention for these artists at the time, they were abandoning the traditional rock band format and forging ahead with the new technology of the times, looking forward to the next millennium.

The end result for R.E.M. was not an artist trying to cash in on a pop crossover with techno. Instead, Up was one of R.E.M.’s most subdued releases. At over an hour long and dominated by introspective and anxious balladry, it can prove difficult to get through in one sitting: Not only was this version of the band unrecognizable practically and sonically, they had returned with an album that looked toward the impending turn of the century with mournfulness and dread. If you were a R.E.M. fan in 1998, still processing the fact that Berry was no longer in the band, this wouldn’t have exactly been the rousing comeback you might’ve hoped for or expected.

Recording Up was an infamously fraught chapter in R.E.M.’s history. One of Berry’s stipulations upon quitting was that they didn’t end the band as a result. And Mills, Buck, and Stipe have all explained in interviews from the ensuing years that none of them were ready to give up making music, to give up this band, anyway. But the remaining trio was still deeply rattled by their friend walking away. Up’s sessions were delayed, and when they did eventually commence they were a broken-down endeavor full of tension. The band members weren’t always present together, they brought in session musicians for the first time, and all of them were trying to figure out what R.E.M. meant, what it was supposed to be, without Berry in the fold. Later, they admitted that Up almost did lead to R.E.M. breaking up.

Stipe once described R.E.M.’s second phase as a “three-legged dog,” an analogy that has stuck and defined the post-Berry years since. That phrase, when applied to the band, is pregnant with the suggestion that they could stumble on but never truly function properly. It’s a line that’s been used over and over when people voiced their discontent with R.E.M. experimenting with their sound during this era. Even if Up had already been planned as the next big R.E.M. aesthetic makeover, it then became the era in which these three men were acclimating to a different kind of upheaval within R.E.M., and you can hear growing pains throughout the work they produced.

All of this was evident from Up’s first notes, in its claustrophobic opener “Airportman.” The song plays like a daydream with far more harrowing scenery unfolding just off-screen, to the side. A gentle drum machine pulse, then distant guitar drones and distorted synths intruding. Stipe’s performance is almost an inversion of his usual presence; he sounds disembodied, a ghost in the machinery or a program trying to replicate an organic voice. “Great opportunity,” he repeats, and it’s hard not to hear it as sardonic amidst the tone of the song otherwise. Its title suggests particular images it could soundtrack: the dehumanizing light trances that occur as you drift through airports, as you sit in unmoving traffic jams surrounded by faceless vehicles, as you move in a massive rush hour crowd in the city about to cram into a train that’ll take you from one gigantic building block to another.

Up’s opener isn’t the only place where theoretically positive sentiments are rendered upside-down. In the desperate “The Apologist,” Stipe keens: “I’m good/All is good/ All’s well, no complaints,” his voice almost breaking before the faux-resolution of “When I feel regret/ I get down on my knees and pray.” There’d be no mistaking the actual origin behind such lyrics. R.E.M. did not sound OK.

Just a couple years beforehand, R.E.M. had offered up New Adventures In Hi-Fi, an album that was weathered and frayed, yet ambitiously sprawling and invigorated by its ability to venture into all kinds of new territory. After that and Berry leaving, Up plays like the grief-stricken comedown. It made good on the exploratory nature of New Adventures, but while there might be revitalization in Up’s creative freedom, it primarily came across like a world-weary answer to how New Adventures portrayed a band on the road trying to capture that same world in quick, impressionistic bursts.

There is little that resembles rock music on Up. “Lotus” is halfway there, if simply because it’s one of the album’s only uptempo tracks and has some more prominent guitar work. “Walk Unafraid” is like a deconstructed rocker, verses suspended in mid-air until the rest of the track tumbles in for one of the only affirming choruses to be found on Up. There’s also the buoyant “Daysleeper,” a lilting pop track that offers a flicker of brightness, at least compared to its surroundings.

Up has more often been remembered for what occurs elsewhere on the album. There are several tear-stained ballads indebted to Pet Sounds’ baroque orchestrations littered across Up, from “At My Most Beautiful,” to “Why Not Smile.” There are strange electronic meditations, like the way “Suspicion” sounds like a whisper of a Bond theme in some kind of space lounge, or how “Hope” nicks the lyrical and melodic pattern of Leonard Cohen’s “Suzanne” for one of the album’s mission statements, grappling with technology and faith over steady-yet-intensifying layers of synths and beats. There are moving, aggrieved compositions throughout, from “The Apologist” to “Sad Professor,” in which Stipe tells the story of a meandering, alcoholic character who proclaims “I hate where I wound up.” At the end of it all, there’s “Falls To Climb,” an airy reflection that seemed steeped in finality. “Someone has to take the fall,” Stipe sings. “Why not me?”

There had been no shortage of downtrodden or cerebral moments in R.E.M.’s catalog prior to this, but those were often delivered via jangling, infectious songs or beautiful and clear folk ballads. Up, in comparison, was beautiful but muddled, by nature and necessity. It was an album born out of and depicting confusion. Consequently, it has always been a divisive entry in R.E.M.’s work. As the first of the non-Berry albums, it has the pressure of being a line in the sand, of being an opening statement on a new era. Meaning this new era’s manifesto appeared to be over an hour of R.E.M. imploding themselves. This new era sounded bleak.

Over the years, when looking back at the expanse of R.E.M.’s work with hindsight, it’s sort of quaint to imagine albums like this being controversial. It is far from novel for a band to toy with electronics or other genres anymore, even if R.E.M. still has adherents who scoff at the band moving away from what made them tick initially. Up was not perfect then, and still isn’t now — it is still difficult to take in as a whole, and could’ve benefitted from one or two or three tracks getting cut. But now it lives on as one of the more flawed and fascinating documents of R.E.M.’s music. Up is very close to being a masterpiece if you can accept a totally different version of R.E.M., and the fractures that keep it from being so are basically part of what it remains such a strange, effecting pivot in R.E.M.’s career. This is the sound of a band approaching legacy status, yet still restless. A band that had just been broken and were trying to put themselves back together in a haze of digital hisses and lachrymose piano confessionals.

Up forms an unofficial trilogy with its two successors, 2001’s Reveal and 2004’s Around The Sun. The former is an underrated answer to the suffocated transmissions of Up; Reveal employed plenty of electronics as well, but while aiming for a lush and woozy kind of summer melancholia. Around The Sun continued an era of their career in which the calling cards of their sound were willfully absent, but to diminishing ends: Thanks more to the production and performances than the songs themselves, the dour acoustic-and-atmospheric ballads of Around The Sun seemed to signify an impending adult-contemporary phase for the middle-aged R.E.M., and it has widely been regarded as their nadir.

Even if this stretch of time was more scattershot than R.E.M.’s past peaks, much of it is still head and shoulders above what most bands can claim. Yet to the extent you might hear a young artist cite R.E.M. as an influence, it’s rarely in reference to later albums like Up. Fans can still squabble over the merits of one version of R.E.M. over the other, or maybe those arguments are now set in stone. But it’s a catalog that still deserves to be revisited, not just for the obviously important work they did in the ’80s but for the era that Up introduced. This was a band almost 20 years into their career. Up was their 11th album. And rather than have inspiration dim, their spirits were more yearning, more curious, than ever before.

Still, the moody trilogy that opened the “three-legged dog” half of R.E.M.’s career is usually written about as a derailed moment in which R.E.M. were treated with deadened interest from press and fans alike. They were, inarguably, in a position that yielded the more guitar-driven, semi-back-to-basics rock of 2008’s Accelerate to be considered a “return to form.” As we know now, Accelerate was actually the beginning of the end, working as a one-two with 2013’s Collapse Into Now as the epilogue for a band that was still vital but starting to look back to all of their older selves in their writing.

The conclusion and summary of those two albums, even if they wouldn’t rank against R.E.M.’s classics from the ’80s and ’90s, has meant that the period of 1998-2008 is often understood as a kind of wilderness era. A three-legged dog moving listlessly, not defiantly. Accelerate arriving just shy of exactly 10 years after Up creates a concise arc: The journey outwards began here, ending with the band losing their way entirely and eventually needing to rediscover the fire that had driven them in more halcyon days.

It’s unlikely that there will ever be a great shift in the critical or fan consensus surrounding these albums, even if Up garners a lot more love than Reveal and Around The Sun. In a sense, it’s a shame that Up will never escape all the crushing context of its gestation and release, of what it begat later on. All these years later, it still has resonance — its pre-millennium dread may place it firmly in its time, and yet still feels legible today. But more importantly, with the distance of two decades, you can hear it informed by its backstory but not overshadowed by it anymore. R.E.M. is over, and their work can be picked apart as a finished project. In that context, Up will always remain a strikingly gorgeous and strikingly sad album that stands as one of their most unique. True, it may remain an album that captures a band searching, not knowing the way forward. But sometimes the most evocative songs are built from the sound of getting lost.