Arnold Layne is the one.

Yes, that’s the one. “Arnold Layne” (1967) is the single that introduced Pink Floyd’s weirdness to the world before they fully leaned into the psychedelic sound on The Piper at the Gates of Dawn and “See Emily Play.”

The song is a shaggy, slightly unsettling story about a cross-dressing clothesline thief. That oddness—the surreal lyrics, the jangly Rickenbacker, the proto-psychedelic production—is what makes it the clear precursor. It’s not fully trippy yet, but you can hear the blueprint: Barrett’s whimsy, the band’s willingness to be weird, and a pop structure that doesn’t quite sit right.

“See Emily Play” came next and turned the dial up to 11. But “Arnold Layne” is where it started.