Plenty of songwriters would kill for one of John Prine's throwaway lines. The praises of Johnny Cash and Bob Dylan are on the record. Marlon Williams and Vance Joy marvel at his gift for "transcendence through the mundane"; "finding beauty in the everyday stuff of life."

A simple title like The Lonesome Friends of Science, or the idea of opening a club in heaven called the Tree of Forgiveness, or that thing about God he dreamt up with Phil Spector back in '78… loose ends can be gold dust in the right hands.

John Prine.

"My wife's sister is really great at archiving things," Prine says in his voice of finely crushed gravel. "I'm totally the opposite. Everything I do is just helter-skelter and here and there and I forget where it's at. I stick it in my back pocket and it shows up in a cigar box 10 years later."

So it happened that one of America's greatest living songwriters found himself checked into the Omni Hotel in Nashville last year with 10 boxes full of random ideas, some of them going back 40 years.