What becomes a ’90s cult-rock legend most? That death is a great career move is a sad cliché, but it’s true nonetheless; witness Kurt Cobain and Jeff Buckley. Second, though—and considerably healthier—is the mysterious disappearing act. In another era, Brian Wilson, Roky Erickson and Syd Barrett all accumulated a lot more cache in their absence than they would have if they’d stayed in the spotlight. And the same was true—minus, we think, the mental problems—after the Clinton years when Kevin Shields and Jeff Mangum retreated to their dark, lonely caves.

Shields damaged the mystique to some degree by returning a few years ago with My Bloody Valentine’s cash-in reunion tour: The band just didn’t sound as impressive, as overwhelming or as awe-inspiring as many of us remembered from back in the day. This long-time fan could not have been the only one in the sold-out crowd of 900 on Tuesday, the second of a two-night stand at the Athenaeum Theatre, worried if the same would be true of Mangum, who has been “resurrected” (his word) after about a decade and a half in self-imposed exile following two albums as Neutral Milk Hotel.

Now, at long last, here was the auteur playing those much-loved—nay, revered—songs from In the Aeroplane Over the Sea (1998) and On Avery Island (1996), onstage again after spending a good chunk of his life avoiding being here, no matter how great the demand. But thankfully, for the most part, the worries were unfounded.

In contrast to celebrated Elephant 6 peers and collaborators Apples in Stereo and the Olivia Tremor Control—or, indeed, to My Bloody Valentine—Neutral Milk Hotel never was about the sound. The band—Mangum and whatever pals he could corral at a given moment to pick up instruments they really couldn’t play—was sometimes embarrassingly sloppy, occasionally endearingly homely, and always ramshackle and chaotic as a live experience. And it remained so now, from the vast majority of the 11-song set that was just Mangum—frantically strummed acoustic guitar and vocals that ranged from a gruff baritone to that famously forlorn, plaintive wailing as it delivered great gushing torrents of Joycean verbiage—to the handful of tunes that were augmented with off-key high school orchestra touches courtesy of some second-tier Elephant 6’ers from the Gerbils and Elf Power. (Good god, it is hard to imagine anyone ever paid good money to hear worse baritone horn!)

What could this show have been if Neutral Milk Hotel had been a real band and Mangum was backed by Elephant 6 giants Robert Schneider, Bill Doss and William Cullen Hart? The mind boggles! But again, Mangum’s project never was about the sound. It always was about the songs—those timeless and enduring anthems that are both intensely personal and inexplicably universal, painful but ecstatic, and inscrutable yet profound. And during an hour-long set that drew exclusively from his two albums, Mangum proved that songs such as “Two-Headed Boy” (parts one and two), “The King of Carrot Flowers” (ditto), “Naomi,” and “Song Against Sex” have lost not an iota of their power.

What, exactly, is the source of that psychic wallop? For all the talk of Anne Frank’s influence on In the Aeroplane Over the Sea, that album, its predecessor, and every other note Mangum ever wrote, recorded, or played live evoked that weird, frightening, confusing yet thrilling period of sexual awakening circa junior high. Few in rock history ever have done it better. And, viewed in that light, it makes perfect sense that he stopped playing these tunes—or playing at all. He grew up, and, as he told Monday’s crowd, he figured things out.

“What have you been doing?” a fan asked on night one. “I’ve been with the love of my life,” he replied. “To me, that’s enough.”

On Tuesday, he fielded a different question: “Jeff, did you ever find your dream girl?”

“Yes, but that’s my own trip,” he said, letting a rare smile flash across his otherwise stoic façade. “Even though I spilled it all over these records.”

Indeed. And the records, the songs, and the man behind them stand undiminished.