When Syd Barrett, co-founder of British psychedelic pioneers Pink Floyd, passed away last year at 60, many around the world, even many who love his music, had to admit that they weren’t aware he had made it that long. Barrett’s music career had already been over for 30 years, the victim of a drug-fueled mental collapse that serves today as a rock ‘n’ roll cautionary tale. But that is not all that endures. Owing to his breathtaking originality, and at times his unmitigated musical genius, Barrett’s influence on pop music is regularly renewed. This week, the 40th anniversary boxed-set of “The Piper at the Gates of Dawn,” Pink Floyd’s 1967 debut album and Barrett’s seminal contribution to psychedelic music, coincides with a new wave of Barrett appreciation.

Beginning a few years ago with artists such as Devendra Banhart, Joanna Newsom, and the band Animal Collective — purveyors of what this era’s critics have termed “freak folk” — fans were led on a rediscovery of experimental, pastoral pop music in the Barrett spirit. These musicians cite Barrett as a crucial influence, and in doing so, illustrate how they differ from Barrett himself, for whom copious amounts of LSD became an indispensable and eventually devastating muse. “The Piper at the Gates of Dawn” is very much a record of the sacrifice Barrett made, probably unintentionally, for art.

The result of regularly dropping acid for two years, which made an already eccentric and artistically inclined young man into an erratic and unreliable bandmate, the album is awash in a wicked blend of puerile imagery and extended, spaced-out solos, defined by what was then an unprecedented alchemy of sonic echoes and guitar slides. Side by side, the reconciliation of childhood fantasy with psychedelic exploration looks more perilous than it probably it did at the time. But then again, much of it was lost on audiences from the start.

The last disc on the new three-CD set, released for the anniversary by EMI records, features bonus material in the form of the band’s earliest singles, “Arnold Layne” and “See Emily Play.” That the former is almost mockingly trippy and psych-friendly is counterbalanced by its unnerving content. “Arnold Layne” tells the story of a transvestite, something that eluded the BBC as the song climbed to no. 20 on the pop charts. “See Emily Play,” on the other hand, foreshadows the potent mixture of childish melodies with much darker themes that became the standard on “Piper.” “Let’s try it another way / You’ll lose your mind and play” goes the chorus, with Barrett’s guitar lending throbbing atmosphere interludes as he slides a Zippo lighter along the frets. He couldn’t have known he had written his own epitaph.

Much less a soundtrack to the summer of love than the Beatles’ “Sgt. Pepper’s Lonely Hearts Club Band,” which was recorded down the hall at Abbey Road Studios while Barrett and company were putting down “Piper,” Pink Floyd’s debut album was Barrett’s contribution (he wrote most of the music and lyrics) to the burgeoning countercultural movement. Like his friends down the hall, Barrett was often playful and ironic in his music — in a nod to whimsical inspiration, he named the album after a chapter head in his favorite children’s book, “The Wind in the Willows.” But Pink Floyd was also much more chaotic than the bright Beatles, and employed lurking dissonances and strange noises throughout the album for effect.

The album’s opening anthem, “Astronomy Domine,” is a spacewalk of a song, flush with references to “water underground” and a quick tour through the solar system. At the time of the album’s release, EMI was concerned about the implications of the band’s hippy image and issued a press release stating that the term “psychedelic” referred to the light show featured in the band’s live performances and not drug use. In all likelihood, anyone who didn’t already enjoy the music never saw the press release, and anyone who did wasn’t fooled.

The songs that follow “Astronomy Domine,” share its bizarre character and sound, working together in a way at once naïve, inventive, and compelling. As Barrett sings on “Bike”: “I know a room of musical tunes / Some rhyme, some ching, most of them are clockwork / Let’s go into the other room and make them work.” The instrumental “Interstellar Overdrive” picks up where “Astronomy Domine” fades out, forging, with its almost structureless wanderings and Eastern flavors, what would soon come to be known as space-rock.

Sadly, Barrett was on a declining spacewalk of his own, and became increasingly unreliable as 1967 wore on. At a concert at the Fillmore West in San Francisco, Barrett stood staring into space, detuning the strings on his guitar. By autumn, the band was forced to bring in fellow Cambridge native David Gilmour to help with live performances and leave Barrett the sole responsibility of writing songs. When that didn’t work, Gilmour replaced Barrett permanently. The1968 album “Saucerful of Secrets” still is deeply indebted to Barrett’s songwriting, and though subsequent albums moved slowly away from his vision, his ideas remained a lodestar for the band as it ventured into new territory, not to mention worldwide popularity.

Tellingly, Barrett’s last works, two solo albums from 1970, “The Madcap Laughs” and “Barrett,” are perhaps even more important to today’s generation of folk musicians than Pink Floyd’s first album. As the space epics faded away, a pared down, truly instinctive and unusual songwriting remained. His adopted austerity, borne as much from a need to bare his soul as from a fear of diving too deep, soon became a bedrock for the punk rock movement, as well as for contemporary musicians who have spearheaded the rediscovery of Barrett for larger audiences. The one difference, as Barrett wrote before he died, is that “the words have different meanings.”