When you were young you were not the king of carrot flowers, but you probably tried to learn “The King Of Carrot Flowers” on acoustic guitar — that and “Two-Headed Boy” and “Oh Comely” and most definitely “In The Aeroplane Over The Sea.” These were all part of a starter pack that was later upgraded to include early Bon Iver, issued to every hobbyist musician and aspiring rock star interested in testing the limits of their vocal range at hipster parties. Whether you had any idea what Jeff Mangum was singing about was secondary.

Merge Records released Neutral Milk Hotel’s second (and thus far final) album on Feb. 10, 1998 — exactly 20 years ago this Saturday — and before the turn of the millennium it had already become a myth. Not much more time had to pass before In The Aeroplane Over The Sea was a genre unto itself. A few years after Y2K, indie rock was overrun with bands that could not have existed without Mangum’s big bang: The Decemberists, Okkervil River, Beirut, even early Arcade Fire, who signed to Merge partly because of their devotion to Aeroplane. That wave has long since crested, but still today groups are out there spinning psychedelic folk-rock suites indebted to NMH (sup, Saintseneca) or further gentrifying their sound into pleasant festival-core (all those “Hey!” bands like the Lumineers and Of Monsters And Men).

The sonic universe this band spawned was actually an offshoot of another sonic universe. With three childhood friends from Ruston, Louisiana, Mangum had founded the Elephant 6 Recording Company, a musical collective strongly rooted in Denver but most closely associated with Athens, Georgia. E6 was a prolific and highly collaborative network of bands — Olivia Tremor Control, the Apples In Stereo, Elf Power, Beulah, and of Montreal among others — who built a cottage industry out of reviving ’60s psych-pop and spinning it out in any number of modern directions. In the ’90s the scene was a critical cause célèbre, and rightfully so, yet these days Aeroplane overshadows the entire operation. It’s not just the most beloved and influential E6 release by far; it’s one of the most beloved and influential indie rock records of all time.

Some of that stature had to do with the mystery surrounding Neutral Milk Hotel and Mangum in particular, which ramped up in Aeroplane’s aftermath. Mangum spent most of the ’90s actively involved in various E6 projects, couch-surfing and touring and recording music at a semi-prolific clip. Whether in your stereo or on a stage near you, he was around. Neutral Milk Hotel in particular toured behind 1996 debut On Avery Island — which Mangum recorded with Apples In Stereo’s Robert Schneider before the addition of bandmates Julian Koster, Jeremy Barnes, and Scott Spillane — and again behind Aeroplane throughout most of 1998. And then, poof, he was gone. The clamor around Aeroplane spooked him out of the public eye for a decade, rarely to be heard from again until the dawn of the Obama administration. “I just feel like these windows open up for something to be honest, and they don’t stay open for very long,” he told Pitchfork in 2002.

As someone who came to the album after Mangum peaced out but before his disciples began proliferating, the whole “lead singer who became a hermit” thing definitely fueled the legend of Neutral Milk Hotel, both in my own experience and the culture at large. That said, the music on Aeroplane is enigmatic and alluring enough to have spawned a similar devotion even if he’d stuck around, as evidenced by the hype that was accelerating around the album even before it crossed over into legend. Although in substance Aeroplane was not so different from the template On Avery Island established, what once seemed like a scrappy convergence of compelling ideas found its apotheosis here. This was one of those rare moments when everything clicks into place and a unique sound and vision unfolds in splendor.

Aeroplane seemed to exist outside of time, ancient yet entirely new. On the musical axis, Neutral Milk Hotel veered from piercingly intimate psychedelic campfire sing-alongs to full-band segments that barreled ahead with haphazard grace, guitars fuzzed out to infinity, everyone bashing away with such rudimental force that the songs seemed ready to topple over at any moment. These foundations were accented by haunting old-world instrumentation — brass band, accordion, singing saw — and always topped off with Mangum’s bracing nasal howl, a noise so alien and confrontational it dared you to take a side. Last night, while explaining Neutral Milk Hotel’s appeal, a friend mused, “I don’t think I’ve ever heard a band whose lead singer’s voice is as much of an instrument. He is part of the horn section.”

People often talk about musicians having a “livewire” effect, but Mangum’s vocals truly live up to that description: They can be shocking and even painful under the wrong circumstances but can also electrify song and spirit. Only intensifying that phenomenon are his lyrics, which paint humongous subjects like sex and death and family in direct, unflinching terms other songwriters couldn’t hope to conjure and wouldn’t dare to sing — at once surreal and achingly true to life. As long as we’re serving up clichés for Mangum to transcend, he rivals David Lynch in his ability to translate unsettling, otherworldly imagery into pop-art beloved by millions.

On Aeroplane, that constituted a startling blend of the physical and metaphysical. Mangum had become deeply fascinated with Anne Frank, poring over her diary and dreaming of rescuing her. Her story is threaded throughout the album in vignettes seemingly ripped directly from Mangum’s subconscious, most explicitly on the rampaging centerpiece “Holland 1945,” one of history’s great “What the fuck are we singing about?” shout-along anthems. In his distinctive bleat, Mangum laments Frank’s death in a Nazi concentration camp “only weeks before the guns all came and rained on everyone” and imagines her reborn: “Now she’s a little boy in Spain/ Playing pianos filled with flames/ On empty rings around the sun.”

That song’s breathless hallucinatory rush is the closest this album comes to clarity, yet even at its most esoteric Mangum’s storytelling was visceral and raw. Sexuality permeates his songs in a way that’s both blunt and cryptic; you never know exactly what you’re hearing even when he’s painstakingly specific: “And in the dark we will take off our clothes/ And they’ll be placing fingers through the notches in your spine.” On the title track, what seems like a whimsical romantic ballad takes a surprising turn: “Oh, how I remember you/ How I would push my fingers through your mouth to make those muscles move/ That made your voice so smooth and sweet.” He later evokes semen-stained mountaintops and a two-headed boy before “Ghost” returns to apocalyptic visions of Anne Frank:

And she was born in a bottle rocket, 1929

With wings that ringed around a socket

Right between her spine

All drenched in milk and holy water

Pouring from the sky

I know that she will live forever

She won’t ever die

These harrowing flights of fancy are grounded by occasional flashes of normalcy — just enough to get you situated in Mangum’s world before he flips you sideways. Opening track “The King Of Carrot Flowers Pt. 1″ begins with memories of childhood fantasy interrupted by the harsh realities of a dysfunctional family: “And your mom would stick a fork right into daddy’s shoulder/ And dad would throw the garbage all across the floor/ As we would lay and learn what each other’s bodies were for.” It’s a gorgeous folk-rock love song that goes to ridiculously dark places by the end: “And your mom would drink until she was no longer speaking/ And dad would dream of all the different ways to die/ Each one a little more than he could dare to try.” Soon enough Mangum is professing his love for Jesus Christ, sludgy guitars are piling on, and we’re off to the races.

All these years later I’m still not always sure what Aeroplane is getting at, but I can’t deny the album’s ability to stir up something inside me. It collides the familiar and the disorienting in a way that renders meaning elusive even as it provokes intense emotional reckoning. As such, Neutral Milk Hotel became something like a secular religion during all those years away, so that when Mangum began playing out again — on an Elephant 6 package tour, at the Occupy Wall Street protest, in a series of solo shows, and finally on a full-fledged Neutral Milk Hotel reunion tour — it was received like the Second Coming. (Never mind that “God is a place you will wait for the rest of your life.”)

At a 2013 solo performance in a Columbus theater, people left their seats at Mangum’s urging to stand in front of the stage and belt out every word. At Coachella in 2014, kids who’d discovered Neutral Milk Hotel long after the band went on hiatus locked arms in a circle and sang along with reverent fervor. The response as the tour traversed the globe really did resemble a tent revival, people flocking to see this roving messiah figure bring his sacred text to life. And although I’m not about to accept Jeff Mangum as my personal lord and savior, I can’t deny how much these performances moved me as well. The spine-tingling beauty we beheld together made it clear why Mangum and his masterpiece had reverberated so widely and why none of its imitators have come close to outshining it.