The Beatles' seventh studio album took the band's music to fresh experimental heights — and helped pave the way for decades of genre-confounding pop masterpieces in the bargain.

Revolver is widely acknowledged as one of the best (if not the best) Beatles record today. But upon its arrival in the U.K. on Aug. 5, 1966, the album faced something of an uphill climb: for one thing, the group had shattered expectations with their previous effort, Rubber Soul, only nine months before; for another, they were in the midst of a PR crisis over John Lennon's offhand remark about the band being bigger than Jesus. It all seems rather quaint today, but at the time, no one knew whether the Beatles — or rock 'n' roll in general — had any real staying power.

If the press narrative surrounding the group painted a picture of uncertainty, the band members themselves betrayed no signs of worry — in fact, when they entered the studio in the spring of 1966, they doubled down on the experimental spirit that suffused Rubber Soul, employing all manner of studio wizardry (including backmasking, varispeeding, and a newly invented gizmo that allowed for instant live vocal doubling) to add extra layers of sonic spice to a batch of songs that included some of their most eclectic, mature works to date.

Looking back on the sessions through modern eyes and ears, it's difficult to really understand just how forward-thinking the entire project really was. After helping to popularize a style of music initially known for its volume and immediacy, the Beatles quickly set about testing the limits of what the genre could do — or if it should have any limits at all. Rock was still a new tool at this stage, and no one knew how many uses it had; with Rubber Soul and Revolver, they proved it was more of a Swiss army knife than the blunt instrument it may have appeared to be at first glance.

This was partly a matter of thematics. Although pop had always reflected the tenor of the times, much of what came before was mannered — material that, although it possessed a greater degree of songcraft than much of what came after, sometimes lacked the raw emotional immediacy that inflamed young rock fans. As they honed their own craft, the Beatles led a vanguard of rock acts that used pop for introspection and pointed social commentary in a more open, easily identifiable way.

"We were right for the time when we came out. The pop scene five years ago was definitely looked upon by 'musicians,' put that in brackets, as a dirty word. Pop was just something crummy. Now I think a lot of things in the pop field have more to them," George Harrison told the Detroit Free Press. "We're very influenced by others in pop music and others are influenced by us... That's good. That's the way life is. You've got to be influenced and you try to be influenced by the best."

Saying he thought the Beatles had given pop music "a bit of common sense," Lennon added, "A lot of it was just a bit insincere, I think. Five years ago you'd find men of 40 recording things without meaning it just to make a hit. Most recording artists today really like what they're doing and I think you can feel it on the records."

But lyrical themes were only half of what made the Beatles' mid-'60s work so progressive — and on Revolver, they pushed the musical side of that equation further than ever. The record offered an almost dizzyingly eclectic array of sounds and styles, leaping from the straight-up political rock of "Taxman" to the soaring, string-enhanced melodrama of "Eleanor Rigby" to the spaced-out experimentation — including backward Harrison guitar solo — on "I'm Only Sleeping."

Harrison, in fact, helped lead the creative charge on the record, expanding the band's palette by dabbling further in the Eastern sounds he'd introduced on Rubber Soul. Fascinated by Indian classical music, Harrison incorporated the sitar and tambura into the sessions — and on "Love You To," he unmoored the Beatles' music from standard Western concepts of musical timing. The song's shifting meter served as the first in a series of experiments with time signatures, while Harrison's fuzztone solo reminded listeners that no matter how far afield they might wander, they remained firmly anchored in their roots.

Revolver was greeted with generally enthusiastic reviews, but like a lot of works ahead of their time, its significance wasn't always recognized. "Yellow Submarine," half of a double A-sided hit with "Eleanor Rigby," was often dismissed as a novelty, and the Lennon-penned closing track "Tomorrow Never Knows," now acknowledged as a centerpiece of the record and a hugely influential example of the ways in which studio technology could be used as an instrument unto itself, prompted bemused and/or bewildered reactions from some critics (Crawdaddy's Paul Williams, for one, wrote that "A good artist doesn’t publish first drafts"). In the States particularly, the band's growing musical prowess was often overshadowed by more tabloid-friendly stuff, like the "Jesus" controversy or conjecture regarding the meaning behind their occasionally obtuse lyrics.

Yet even at the time, many critics listened to Revolver and heard pop's boundaries ripping wide open. The album, as a matter of course, ended up hitting the top of the charts on both sides of the Atlantic, selling millions, and earning a Grammy nomination. But more importantly, it proved widely influential — not just for contemporaries like Beach Boys leader Brian Wilson, but for generations of listeners that grew up into artists in their own right and who, whether consciously or not, followed in its wake.

"Perhaps there won't be quite as much screaming at Beatle concerts this year, and perhaps everyone isn't aware of the musical impact and importance of Revolver," wrote an uncredited critic for KRLA Beat. "But it is certain that Revolver has fired a shot which will be heard around the globe wherever people really care about the music they are listening to."

While few contemporary artists (or even very many of their disciples) could match the Beatles in terms of creative discipline or willingness to experiment, the echoes of Revolver's shot reverberated through a number of similarly influential works in subsequent years. And although the band's pioneering use of studio technology arguably helped pave the way for the stultifying rise of over-production in later decades, the record's experimental spirit proved rock could be more diverse than anyone realized — that it could incorporate everything from raga to dissonance without losing its power and beauty. Although it would be something of a stretch to list the Beatles among the direct influences of outsider '60s bands like the Velvet Underground or the Stooges, it's worth questioning whether their sounds would ever have penetrated any corner of the mainstream if records like Revolver hadn't paved the way.

That spirit remained well beyond the band's breakup. Toward the tail end of the '70s, after the Beatles had long since parted and rock had spread into the cultural mainstream, an array of indie acts like XTC and Wire sowed the seeds for what would eventually become known as "alternative rock" through the release of little-heard but widely influential records that rejected the standard order much the same way Revolver had. And by the late '80s, the album's rough blueprint could be felt all over the alternative dial — from radio-friendly acts like R.E.M. to fringe bands like Pixies. When the alternative explosion went off in the early '90s, it was triggered by the sounds of Pearl Jam (whose frontman Eddie Vedder counted a mashup cassette of Revolver and the White Album as one of his earliest influences) and Nirvana.

And then, of course, by the mid-'90s, as alternative became a predominant genre unto itself, along came the most Beatles-influenced band of the bunch — Oasis — with a string of Beatlesque hits that unabashedly evoked the Fab Four's legacy. As far as chief songwriter Noel Gallagher was concerned, not only were the Beatles the best band of all time, Revolver was the sonic touchstone for the movement that defined the entire decade. "The ’90s," he told iTunes, "would never have happened without this album."

"It’s a masterclass of how to make guitar pop. That’s just it," Gallagher told The Quietus. "They took what the Beatles had been, they did Revolver and then the next week they’re making ‘Strawberry Fields Forever.’ They’re a completely different band. It’s a cliché to talk about it now because it’s so well-known, but this is a mindblowing album."

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