The chord progression Tom Petty came up with for "Free Fallin'" is simple enough that pretty much anyone can play it — and figuring it out is enough to make a beginning guitar student laugh out loud in wonder. As it turns out, laughter is exactly what Petty was going for when he wrote the song.

Looking back over his career in a Billboard interview conducted prior to his induction into the Songwriters Hall of Fame, Petty recalled how he wrote "Free Fallin'" while joshing around in the studio with producer Jeff Lynne during sessions for what would become his Full Moon Fever LP. "I was playing the keyboard and I just happened to hit on that main riff, the intro of the song, and I think Jeff said something like, ‘That’s a really good riff but there’s one chord too many,’ so I think I cut it back a chord and then, really just to amuse Jeff, honestly, I just sang that first verse," said Petty. "Then he starts laughing."

Out of the chuckles arose a song that — in spite of Petty's initial goofing around — refused to remain unwritten.

"Honestly, I thought I was just amusing Jeff but then I got to the chorus of the song and he leaned over to me and said the word, ‘freefalling.’ And I went to sing that and he said, ‘No, take your voice up and see how that feels,'" said Petty. "So I took my voice up an octave or two, but I couldn’t get the whole word in. So I sang ‘freeee,’ then ‘free falling.’ And we both knew at that moment that I’d hit on something pretty good. It was that fast."

Alone in the studio after Lynne left for the day, Petty fleshed out the rest of the "Free Fallin'" demo, and — much to his partner's surprise — had a finished song waiting to be tracked at the next session. "I played him the song and he was like, ‘Wow, you did that last night?’ And I was like, ‘Yeah,'" he recalled. "And he said. ‘We’ve got to go cut this,’ and we just took off to Mike Campbell’s studio where we knew we could get in and get it done that day. So we went in and made the record that day."

The rest was rock 'n' roll history. Released as the third single from the wildly popular Full Moon Fever, "Free Fallin'" ended up becoming Petty's biggest pop hit, peaking at No. 7 on the Billboard Hot 100.

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