Given Big Star's short and troubled lifespan, the wealth of rarities on the massive retrospective, 'Keep an Eye on The Sky,' which is due Sept. 15 on Rhino Records, is surprising. Among many other treasures, it includes a previously unreleased demo version of 'There Was a Light,' which even surprised drummer Jody Stephens, who, alongside bandmates Alex Chilton and Andy Hummel, played on the recording.

"I remember the three of us going in to do this and how excited I was with the outcome and how it sounded," Stephens tells Spinner of the session. " We even thought about using those versions for the album, but we wound up re-cutting them." Of particular note, perhaps, is the pop ballad's poignant soulful vocal. "Alex was delivering the lead vocal and he had -- and still does have -- a soulful way. You know what? I'm probably singing background on that." Indeed, he is. "As a three-piece," he says, referring to Bell's departure after the release of Big Star's 1972 debut, "I got to do a lot more singing."

The collection culls from 1968-1974, plotting the career of these Memphis musicians who created a post-Fab Four pop rock style that eventually became known as power pop. It influenced a legion of bands from the Posies, whose Jon Auer and Ken Stringfellow have performed as part of Big Star since 1993, to Fountains of Wayne.

Stephens can't remember the exact date of this particular recording session, which also included demos for 'I Got Kinda Lost,' 'O My Soul' and 'Back of a Car,' but he estimates it was late 1972 or early '73. "I haven't heard it in years and I thought the tape was lost. Those four tracks I thought were long gone."