Last year, on the first anniversary of Prince's death, I interviewed Ben Greenman, the author of Dig If You Will the Picture: Funk, Sex, God and Genius in the Music of Prince. One line from that conversation has stuck with me. "I had this theory when I was a teenager that Michael Jackson was a space alien," Greenman said, "and Prince was a normal guy who was tremendously talented."

With Prince's Paisley Park vault opening up, that mix of humanity and extraordinary talent will soon be on full display. On September 21, Prince's estate will release Piano and a Microphone 1983, a collection of songs recorded to cassette at Prince's Kiowa Trail home studio in Chanhassen, Minnesota, and found recently in the Paisley Park vault. It includes some familiar hits ("Purple Rain," "International Lover," "Strange Relationship"), a much-loved B-side ("17 Days"), a pop cover (of Joni Mitchell's "A Case of You"), and a famous spiritual (the recently released "Mary Don't You Weep"). The last three songs on the record, however, have never been heard before in any form. The last of them, "Why The Butterflies," is premiering below.

Like everything on Piano and a Microphone—a demo album—"Why The Butterflies" is a sketch of a song. Prince moves up and down the piano for little flourishes, but he's only really tinkering with one chord. He uses around a dozen words in total, and they all grow out from one root: "Mama…" grows into "Mama, what's this strange…"; on a parallel branch he asks, "Mama, what's this shaking in me?" It's a hint at childlike wonder.

But it's also rich and varied, with Prince testing out every possible vocal variation and murmur and falsetto flight and bass dip and babyish croak over six-and-a-half minutes. "Why The Butterflies" is an insight into Prince's creative process and an example of his remarkable gifts—even here, with the cassette's white noise so loud that it becomes a third instrument, his experiments are fascinating. It's also proof that, despite the slick and godlike heights of Purple Rain or Sign 'O' The Times, Prince was human—"a normal guy who was tremendously talented."

In the liner notes to Piano and a Microphone 1983, Don Batts, Prince's engineer for the sessions, writes: "Prince’s talent was extraordinary—bordering on otherworldly—and his energy and drive were inexhaustible." That's clear on the beautiful and grainy "Why The Butterflies," and it'll likely be clear on most of the work that comes out of the vault in the coming years. Prince was extraordinary, "bordering on otherworldly." But he was close enough to our planet to feel real.