It’s taken Pink Floyd 40 years to do anything as crowd-pleasing as replenish their first album with the other songs they released that same astonishing year. But that’s part of what makes them the British Invasion’s snootiest, most truculent band.

Even at the start, with elfin Roger “Syd” Barrett in charge and saturnine Roger Waters still largely preoccupied with bass guitar, they kept their distance — already disdainful of the pop carousel that had, from the release of the catchy and peculiar “Arnold Layne” in March 1967, propelled them into the limelight.

Following the practice of the day, The Piper at the Gates of Dawn shunned the singles that preceded it and instead presented a sprawling freak-out, with Barrett and Waters pummeling the drone riffs of “Interstellar Overdrive” and “Lucifer Sam.” Meanwhile, Barrett’s lyrics melded Lewis Carroll nursery surrealism with sci-fi imagery, offsetting outrageous whimsy (there’s one song about a gnome named Grimble Grumble) with dark, sinister vibes attributable to the onset of LSD psychosis. The Byronic guitarist had dabbled in hallucinogens since 1965 (a film of his alleged “first trip,” made by a school friend, is easily found online). But by the end of ’67, with Pink Floyd poised for success, Barrett was disintegrating, and by spring he’d been replaced by pal David Gilmour, casting the band into a songwriting crisis they didn’t fully resolve until five years later, when Waters helmed the staggeringly successful Dark Side of the Moon.

Coming a year after complications from diabetes killed Barrett, Piper now includes everything great he recorded with Floyd and is designed in tribute to him by their art guru Storm Thorgerson. Despite subsequent triumphs, the surviving Floyds are still troubled by guilt over Barrett’s sacking and faintly irked that for musicians from Blur to R.E.M., he will always be the cool one.

Barrett’s flair for the unpredictable still has the power to knock you off balance, and his wry, bashful voice echoes across the decades, a little boy lost in every way. At the end, aged 60, he led a disturbed, reclusive but essentially functional life in which rock & roll played no part. He was the self-propelled victim of a more reckless era, but, as this comprehensive three-CD doorstop serves to underline, he burned bright and passing strange.
Download: “Arnold Layne,” “See Emily Play,” “Interstellar Overdrive”