On May 12, 1965, the Rolling Stones finish the studio recording of “(I Can’t Get No) Satisfaction,” their first major hit. The song, which catapulted the ascendant British blues-rock group to global fame, had an unusual origin: Less than a week earlier, during the early morning hours, the band's bleary-eyed lead guitarist Keith Richards had bolted up from his bed, grabbed a tape recorder and laid down the song's opening riff, now considered one of the greatest pop hooks of all time.

He then promptly fell back to sleep. "I had no idea I'd written it," RIchards wrote in his 2010 memoir Life.

“When I woke up in the morning, the tape had run out,” Richards recalled many years later. “I put it back on, and there’s this, maybe, 30 seconds of ‘Satisfaction,’ in a very drowsy sort of rendition. And then it suddenly—the guitar goes ‘CLANG,” and then there’s like 45 minutes of snoring.”

It wasn’t much to go on, but he played it for Mick Jagger later that same day. “He only had the first bit, and then he had the riff,” Jagger recalls. “It sounded like a country sort of thing on acoustic guitar—it didn’t sound like rock. But he didn’t really like it, he thought it was a joke… He really didn’t think it was single material, and we all said, ‘You’re off your head.’ Which he was, of course.”

With verses written by Jagger—Richards had already come up with the line “I can’t get no satisfaction”—the Stones took the song into the Chess studios in Chicago on May 10, 1965, and completed it on May 12 after a flight to Los Angeles and an 18-hour recording session at RCA. It was there that Richards hooked up an early Gibson version of a fuzz box to his guitar and gave a riff he’d initially envisioned being played by horns its distinctive, iconic sound.

Though the Stones at the time were already midway through their third U.S. tour, their only bona fide American hits to date were “Time Is On My Side” and the recently released “The Last Time.” “Satisfaction” was the song that would catapult them to superstar status. Forty years later, when Rolling Stone magazine ranked “Satisfaction” #2 on its list of the “500 Greatest Songs of All Time,” it put the following historical perspective on the riff Keith Richards discovered on this day in 1965: “That spark in the night…was the crossroads: the point at which the rickety jump and puppy love of early rock and roll became rock.”