Psychedelia can be defined as moving from one state to another. And that doesn’t have to mean drugs. For example, there is nothing more psychedelic than nature. And just like nature is unpredictable, mysterious, and also familiar, so too has been Animal Collective’s music.

When it came out, a lot of critics called Animal Collective’s Merriweather Post Pavilion the best album of 2009, even though we were only days into the year and the album hadn’t even officially come out yet. But it stuck. Ten years later, the hype surrounding the eighth studio album by Animal Collective looks unparalleled, almost ridiculous for an indie album. It arrived at a time when blog culture and file sharing were capable of escalating the discussion around music, serving as de facto gatekeepers to the indie mainstream and helping a mysterious hippy band from rural Maryland to crack the mainstream code and rewire a lot of brains in the process. Over the past two decades, the group has gone from hiding behind masks and playing some really cooked live shows in Brooklyn art spaces to headlining international festivals. The way we consumed music back then was a bit more wholesome and grassroots compared with the top-down approach of the streaming era. Merriweather might have been the last time we actually had a sustained discussion about an album online. It seemed to be nonstop for months, whereas today we yell about an album for a couple days on Twitter and then forget about it. “Things were a bit more conversational at that time. Whether it was our record or any record, it seemed like people were conversing about it. Blogs helped keep a light on the record,” said group member Brian Weitz, the Animal Collective member who goes by Geologist.

When it was released, Merriweather hit no. 13 on the Billboard Top 200, next to Lady Gaga, Pink, and Mariah Carey—a virtually unheard-of feat for a weird indie band at the time. The album’s modern wide-screen Technicolor sound, incorporating communal singing, American hip-hop rhythms, and European techno drops filtered through the group’s own hazy prism, created a seminal record for the internet era. It was the peak of psychedelia’s second coming, this time in the form of a software update emerging from the earth. This was as human as electronic songs could get in the 21st century. Animal Collective are masters of repetition, but they do it in a way that isn’t boring. And on Merriweather, they crafted songs that feel like they could go on forever.

In 2006, the group was in the desert valley of Indio, California, playing Coachella for the first time. Members experienced a bit of a revelation after watching Daft Punk perform its revolutionary pyramid set, which helped touch off the EDM movement in the States. “It’s one of the best shows I’ve ever seen,” said Dave Portner, the Animal Collective cofounder who goes by Avey Tare. “It showed me how electronic music can be put on a large scale.”

For Noah Lennox, who goes by Panda Bear, the show was a marker for him to look back at the band’s previous work and how they would present their music in the future. “The audiences were bigger, and we figured people coming to the shows now wouldn’t know everything and probably had one or two songs that they wanted to hear. We wanted to throw a bone to those folks by playing older stuff,” Lennox said.

“The idea of remixing yourself that we took away from that show was really inspiring,” Weitz recalled.

Five years later, the group would play between Mumford & Sons and headliner Arcade Fire on that festival’s main stage, but first they would record the album that would help get them there. Lennox had already been releasing sample-based music on his own during this time, mining records and the farthest corners of the internet for 2007’s Person Pitch, which inspired tons of musicians to make music on their laptops in the coming years. That album really got the gears turning in the other members’ minds about moving from more traditional instruments to samplers and sequencers. But instead of sampling other sources, the group made the decision to mainly sample themselves. They would jam on a beat or melodic riff, then chop those into loops and process them. (“We made the samples to perform the songs,” said Lennox.) The group played samplers and mixers with each other the way a drummer would play with a guitarist or keyboard player. With members spread out across America and Europe at the time, the group emailed music back and forth for the first time.

Three members of the group—Avey Tare, Panda Bear, and Geologist—had booked a tour of smaller clubs during the recording of Strawberry Jam and needed new material. (Josh Dibb, a band member who goes by Deakin and had appeared on pre-Merriweather Animal Collective albums, had already told members he wouldn’t be part of the next era of songs.) The group back then wrote new songs for tours, then recorded them after developing them live, the album serving almost as an end document. By the time Animal Collective would release an album, they were already on to playing newer songs. Live audiences had been hearing these songs for almost two years before their official release, but when the tracks arrived in their studio form, they still felt like a revelation. The group, then in their late 20s, started playing Merriweather songs in May 2007, nine months before recording the album. Their seventh studio album, Strawberry Jam, hadn’t even been released yet. “It was actually good to test out new stuff in a lot of these small clubs with a lot of intimate and raw energy between us and the fans,” Weitz said.

“There was a sort of somber playfulness to it that was really hard to pin down at the time. In a weird way sort of open and vulnerable, yet with a head held high.” —Ben Allen, MPP engineer

When it came time to record the album, the group recruited a then relatively unknown engineer named Ben Allen, whose background was in assisting with big-budget records for Puff Daddy and CeeLo Green. Allen had never listened to the band but was intrigued and agreed to engineer the album, convincing them to forgo their original plan of recording in Jamaica for a converted gas station in the sleepy hills of Oxford, Mississippi, part of Tornado Alley. Allen focused on bringing out the vocals and bass lines, the latter of which was never really featured on an Animal Collective album before. The group tracked the record during the winter thaw of February 2008 in what remains one of their more seamless recording experiences. “It was one of the happiest sessions for sure. It’s just one of those moments in life where everything kind of goes your way,” Lennox said.

“I feel good we were able to still write songs in line with our tastes and how we always write music. I guess we were able to push the songs so the songs stood out a little bit more to the listener’s ear,” Portner said.

These songs felt submerged, pulsating with bass and upfront percussion. Vocally, Portner and Lennox’s singing aligned like an eclipse. There’s the feeling of a dam bursting during the beginning of “In the Flowers,” the fractal chanting of “on my father’s grave” in “My Girls,” the elliptical outro of “Daily Routine.” The binary reverie of “Taste” sounds like two songs playing at once, depending on whose singing you follow. There was something in there for everybody—this was a globalized album where mainstream dance rhythms were on equal footing with African folk instruments. “There was a sort of somber playfulness to it that was really hard to pin down at the time. In a weird way sort of open and vulnerable, yet with a head held high. At the moment that was very fresh,” Allen said.

But strip away the dense layers of production, and you’re left with a collection of very straightforward songs. Lyrically, the words are simple as well, longing for friends, family, and those at home. (Sample lyric: “No more runnin’ says my mind / All this movement has proved your kisses are too fine.”) Still, as much as Merriweather’s grab for the center went for pop’s sweet spot—it was named after the major outdoor amphitheater in Columbia, Maryland—these were still not tunes you could casually throw on at a party. The band often got criticized for exaggerating music, as if they were satirizing music itself. “I remember getting a lot of bad live reviews saying, ‘These guys made a pop record, and they don’t come and deliver the pop hits. They just spend too much time indulging their spaced-out ambient drone improv,’” Weitz said. “Back then, we were still fighting this uphill battle that everything we did was this big hyperconceptual thing to fuck with people, like things weren’t coming from a sincere place,” Weitz said.

“‘My Girls’ was the right message for the right moment—lyrically, it’s not all that far off from ‘Thrift Shop’ or ‘Royals’ as a pop song that celebrates rejecting materialism.” —Ian Cohen, music critic

People use the word “zone out” as a disparaging phrase toward the band’s music, like it’s something to be ignored, but it’s more like something you zone into to cancel out the rest of the world. Music like this seems more important today, when a million things are vying for our attention and the world has gotten a little more difficult to make sense of. Even if you don’t like the group’s music, Animal Collective forces you to have an opinion, to pay attention. And this was an album you didn’t so much listen to as feel. Like psychedelics, the music could move you deeply but also leave you struggling to articulate what it all meant.

Merriweather was polarizing: You either loved or hated this record. There was no consensus on whether it was too out there or too pop, electronic or organic, learned or improvised. Animal Collective is really good at mixing disparate elements into something deceptively complex. The lines of the Merriweather songs were a little easier to trace, but still done on their terms. Music publications with their foot in the indie scene saw it as the group’s pop statement, while more mainstream publications remained vexed that the album’s sugary melodies were muddled by weird noises. Even the few negative reviews couldn’t agree on reasons to dislike it. One commenter hilariously called it “the most stressful album of ’09.”

Pitchfork, which had been praising each subsequent Animal Collective release a little more than the one that preceded it, gave the album a 9.6. (Only Kanye West’s My Beautiful Dark Twisted Fantasy has received a higher score—a 10—for a new release in the last decade.) By the end of the year, the album landed at the top of many critics’ lists, including Village Voice’s Pazz & Jop poll.

“As far as weird music, I feel like my gauge on that is so far off the grid. There’ll be stuff that I think is totally straight ahead, and people will be like, ‘What are these weird sounds?’ Perception is a funny and elusive thing,” said Lennox.

Animal Collective has always been a hard band to talk about. Today, some say they’ve become too Saturday-morning cartoons, as if they are making music exclusively for toddlers. Suddenly, they don’t seem cool. Solo releases seem more interesting than group releases these days.

There are music critics who look at a body of work within a political and cultural context; within those parameters, Merriweather’s arrival during the early Obama era represented a celebration of better days ahead. But there were still a lot of problems. Millennials were entering the workforce for the first time, burdened by an economic meltdown. When Lennox sang, “I don’t care for fancy things or to take part in the freshest wave,” it resonated with young people who were unsure as to whether they would ever own things and what the mad dash was all for.

“‘My Girls’ was the right message for the right moment—lyrically, it’s not all that far off from ‘Thrift Shop’ or ‘Royals’ as a pop song that celebrates rejecting the materialism that people assume infects all other pop,” said Ian Cohen, who’s covered music for Pitchfork, Noisey, and Stereogum over the past two decades. (“My Girls” remains the band’s most streamed song by far with more than 25 million listens on Spotify.)

But looking at the music through the eyes of 2019, Merriweather seems almost naive or mawkish. A lot of popular music today is just straight-up sad. There is Travis Scott’s sad trap, Lana Del Rey, and the emo-rap of Lil Peep and Juice WRLD. The aughts indie-rock era is also being reevaluated on new terms. “The influx of more genre coverage, more diversity in staff, etc., have started to foment this view that indie rock in the 2000s was this super white and bro-y and apolitical thing, and publications were just fantasy baseball leagues that reviewed records, and so the entire canon needs to be questioned—and AnCo is kinda the easiest target for that,” said Cohen via email.

The lead-up to the album also created a bit of a brouhaha. “Brother Sport,” Merriweather’s marathon Afro-rave closer, leaked two months before the album was released and prompted anti-piracy company Web Sheriff to send cease-and-desist letters to blogs. An email purportedly from the band asked fans to leak the album in full, but it wasn’t actually from them; hackers were able to mimic a group member’s email. On Christmas Day 2008, a rip of the album leaked, causing the band to push up the vinyl release of the album to January 6. “It was a function of not understanding all the tools at the time people had to leak records, and maybe just not identifying it as a similar excitement. I probably would have behaved the same way had I been born five years later,” Weitz said.

“Honestly, the last 10 years has been swamped in reverb. It’s like we unleashed a beast.” —Ben Allen

But in a way, Merriweather served as somewhat of an accidental precursor to how albums would be rolled out in the streaming era. Today the work of an album as a whole has been fragmented into branded playlists via hyper-pinged algorithms, which allow “everybody to sort of live in their own world,” Weitz said.

“The way the record leaked, and having little pieces of information come out, I feel like it is kind of the way proper labels do it now. The release date has become the end of the album cycle, and everything up to release day is slowly trickling out songs and videos,” Lennox said.

Strictly looking at the music, Merriweather’s low-end, shimmering-pool aesthetics undoubtedly spawned similar production values in the few years after its release. Bands like Alt-J, Deerhunter, and Tame Impala have used Merriweather’s psych-pop formula. “It was the return of reverb. People really weren’t using reverb the way we had been using it on that album for a long time. And honestly, the last 10 years has been swamped in reverb. It’s like we unleashed a beast,” Allen said.

Whereas the influence of Panda Bear’s Person Pitch is easier to delineate, Merriweather’s legacy is a bit harder to pin down. The band brought the color back into music at a time when indie rock in particular was almost too serious, tightly recorded, and uncultured. This was how it was going to be from now on: samplers instead of guitars, vibes over rocking out. And it’s still basically like that. Animal Collective’s decentralized, open-door policy was the new band prototype. It seemed like everyone was playing a stand-up kit with just a floor tom and a sampler, singing music with tons of delay. Their influence is so ubiquitous that Beyoncé recorded a song without knowing it was an AC song first. It’s hard to find a better independent release than Merriweather in the past decade.

“People are critical of our most recent records in terms of being full of all these busy, bonkers kind of sounds. Then I listen to ‘Taste’ and I’m like, ‘It sounds just as crazy to me. There is just more reverb on everything,’” Weitz said.

Portner, meanwhile, doesn’t try to think much about what the group’s music means. “That record I wish very little was different. It’s one for us that felt really good,” Portner said. “If this record brought people into the conversation that hadn’t previously been in there, shed some light or open some doors for other things, then I feel pretty good about that. And I feel like it has.”

Both Weitz and Lennox are equally stumped as to the album’s legacy. “Man, I have no idea. Talking to friends, it’s not one of their favorites. But it’s one [listeners] like a lot more than the others,” Lennox said. The thing with Animal Collective is that since each release sounds like a different band, fans come and go. Lots of people like the back-to-the-land nurture of Sung Tongs, or the crystal-palace fantasia of Feels more than Merriweather. “I think our ears have definitely shifted to a point where we have a better gauge of how people are gonna react to certain things,” Portner said. “To us there has always been some kind of pop element to the songs and the other stuff that was there is the Animal Collective stuff, the natural way of making music.”

In keeping with their spirit as primarily a live band, some members are more attached to the Merriweather songs in their touring form, when they were breaking apart and congealing into new forms each night. You never really knew where one song started and one ended. Recently Weitz and Portner have been revisiting sets they recorded from 2009. “I’m still kind of confused, in a good way, and awed by what I hear,” Portner said.

“Listening to those shows have made me remember how much of a live era it was. There was so much improvisation, and things morphed over time, and being like, ‘I forgot about this part’; that sample that never even made it on the record but we used in every show to go into ‘Fireworks.’ And we’d just look at each other and just be like, ‘Whoa, I totally forgot about that,’” Weitz said.

As for the group’s future, members plan on getting back together sometime in 2019 to work on new material based around a couple of live shows done in New Orleans last year. “We wanted to do something swampy and jazzy,” Weitz said.

After making music together since they were kids, Animal Collective have developed a language only they seem to know, one that is very much informed by a lifelong friendship but also something that resonates with a lot of people. Now as members of the group approach 40, that language continues to evolve.

Justin Kloczko is a reporter who’s covered politics, criminal justice, music, and the law for The Daily Beast, Vice, and The Outline.