Additionally, Sgt. Pepper‘s groundbreaking sonics – its mix of pioneering textures, complex composition and inventive recording techniques –also won the album standing as a legitimate art form that revised and extended classical music’s archetypes. (This achievement also imbued much of rock itself with a new prestige and aspiration.) In part, the unprecedented acclaim resulted from Paul McCartney’s insistence on the album as a conceptual song cycle that existed as a whole entity: The Beatles, posed in ornate Victorian brass-band military costumery on the cover, were playing a fictional band, singing from perspectives free of any indebtedness to their prior musical sensibility and well-established images. (Ringo Starr later described it as “a bunch of songs and you stick two bits of ‘Pepper’ on it and it’s a concept album. It worked because we said it worked.”)

But that was 50 years ago. A lot changed – including the Beatles, who ended acrimoniously in 1970. What can we learn now from Sgt. Pepper‘s new incarnation? As it turns out, Giles Martin reveals considerable new wonders – particularly in his stereo remix of the original album (which appears in all the new editions, and as a standalone disc and digital download). The remix, in fact, provides a long overdue epiphany. Martin observes in his liner notes: “The original Sgt. Pepper’s Lonely Hearts Club Band was primarily mixed as a mono album. All care and attention were applied to the mono LP, with the Beatles present for all the mixes. … Almost as an afterthought, the stereo album was mixed very quickly without the Beatles at the sessions. Yet it is the stereo album that most people listen to today.” In other words, popular music’s most elaborate and intricate creation – and one that helped end the mono era – wasn’t made to be heard in stereo.

Perhaps that’s been Sgt. Pepper‘s unlikeliest secret, though for those who compared the original mixes over the years the difference was noteworthy: The mono version hit harder, sounded fuller, whereas the stereo soundstage diffused that force. You hear it from the start: The mono version of the title track jolted full-force, particularly in the collusion of Paul McCartney’s bass and Ringo Starr’s storming drums. Martin has said that in attending to the new album’s mix he was aiming for a “3-D mono” rendition – and he has achieved it. The titular opening track finally jumps out of the speakers in a more centralized stereo: It’s sharp, vivid, forward leaning – the sound of a big band doing very big things and not fucking around about it one bit. Indeed, everything here is more vibrant and forceful; it’s for the ears of today. Ringo’s three-beat drum salvo that launches the chorus in “Lucy in the Sky” now gives new gravity to the song’s hallucinogenic imagery and chimerical whirl; “Getting Better” has an aggression that belies the song’s title claim, making clearer the idea that this is a song about a fucked-up man contending to overcome himself and confessing his flaws and confusion; “Good Morning Good Morning”‘s horns and relentless rhythms propel the distress implicit in John Lennon’s vocal (Lennon later said he was going through a personal hell as the Beatles recorded Sgt. Pepper, and this song reflects that); and “A Day in the Life” acquires even more frighteningly palpable depth. The song has always stood outside of Sgt. Pepper‘s phantasmagoria. It was a vision of dreams, death, chaos, revelation, and it held and scared us as it faded into a final oceanic piano chord, reverberating around a room of keyboards. That moment now holds and scares even more; its finality sounds boundless.

Extra discs in the various Pepper packages consist mostly of the album’s tracks in development (the fourth of the six-disc box showcases mono versions). It’s particularly fascinating to hear the simple and spare origins of John Lennon’s “Strawberry Fields Forever” (recorded for the album but released earlier in February 1967 as a single, along with “Penny Lane”) and “A Day in the Life.” Both songs sound abstracted and simple at their outset, then grow otherworldly; they are mesmerizing transfigurations, and they transmute right before our ears. Some songs arguably benefit from their fundamental, pre-effects treatment: “Being for the Benefit of Mr. Kite!” is spookier in its Take 4 version, and much warmer in Take 7, with McCartney’s pumping bass steps and Ringo’s razor-sharp cymbal accents. Similarly, newly released takes of “With a Little Help From My Friends,” “Lucy in the Sky with Diamonds,” “Lovely Rita” and “Fixing a Hole” demonstrate that before curlicues and overdubs were added there was still a quartet sensibility at the heart of most of this music (The Beatles never would have made this music had they kept touring, but contrary any claims, they could have effectively played almost everything here live and stripped.) You especially feel the band as a tight unit in “Getting Better,” “Good Morning Good Morning” and the blazing “Sgt. Pepper’s Lonely Hearts Club Band (Reprise).”

By contrast, “She’s Leaving Home” which featured Paul and John’s voices accompanied by a string nonet but none of the other Beatles. (The song’s writing credit now appears solely as Paul McCartney’s. Several other credits have shifted as well: the title track, along with “Lucy in the Sky with Diamonds,” “When I’m 64,” “Good Morning Good Morning,” “With a Little Help from My Friends,” “Getting Better” and “Being for the Benefit of Mr. Kite!” appear as McCartney-Lennon creations, rather than the more familiar Lennon-McCartney attribution. “A Day in the Life” shows as Lennon composition, while “Lovely Rita,” “Fixing a Hole” and “Sgt. Pepper’s Lonely Hearts Club Band (Reprise)” appear under the original Lennon-McCartney arrangement.) George Harrison’s “Within You Without You” stands outside the Beatles. Harrison set aside his guitar, instead playing sitar and conducting Indian classical musicians while George Martin conducted a conventional classical string section. “Within You Without You” was derided by some as tedious and preachy, but it has weathered beautifully. Sgt. Pepper has often been characterized as a gestalt: a whole that was greater than the sum of its parts. But Harrison’s Hindustani song and Lennon’s “A Day in the Life” proved the exceptions. “Within You Without You”‘s message of transcendence and unity – and of haughty judgement – was, as one critic observed, the conscience of Sgt. Pepper. “A Day in the Life,” the album’s closer, dispelled the whole fantasia that had come before. It was haunted – the ghost that outlasted the dream.

Sgt. Pepper‘s moment – its glimpse of a Garden of Eden, its florid sensibility, its depiction of “Cellophane flowers of yellow and green/Towering over your head” – could not hold. Bob Dylan moved back to folk music late that same year with John Wesley Harding – never once touching psychedelia – and the Rolling Stones reasserted rock & roll as a gritty, edgy, blues-based vocation with “Jumpin’ Jack Flash,” in April 1968. The Beatles were chagrined. The year following Sgt. Pepper‘s release, Lennon himself deprecated it as “the biggest load of shit we’ve ever done.” By 1969 the Beatles had adopted a new motto: “Get back to where you once belonged,” and proceeded accordingly, until they fell apart. Even so, the album itself never fell from its pedestal. It has always been seen as an unsurpassed milestone. Not so much for its psychedelic vision, rather for what it set loose in form, cohesion, texture, layers, adventurism, technology and utter boldness. Those possibilities bore fruit across the breadth of popular music, in Born to Run, Around the World in a Day, OK Computer, Yeezus, Lemonade and To Pimp a Butterfly, among countless others. Also, George Harrison’s “Within You Without You” opened ears not only to Indian sounds but to widening vistas of world music. We live in soundscapes now that Sgt. Pepper helped lay the groundwork for.

Above all, though, the album represented accord and imagination as means to enlightenment – a last bulwark of agreement before the dark set in. We have lost a lot since the summer of 1967, including any more chance of being naïve. But now, thanks to Giles Martin, we can hear the Beatles’ apogee as it was always meant to be heard. That won’t save the world, but it can still beguile us, and that remains a generous miracle.