One night, the bass player called out at the last minute, and so we sat around and fooled with an acoustic guitar -- just JJ (guitar), Frank (drums) and I (guitar). We were doing an acoustic gig, and so we went through a lot of quieter vocal pieces, including this one.
Right from the start, we found we fell naturally into our parts -- and so we added it to the lineup. We have JUST started to work in Bill's (bass) low end vocal ... hence this practice run through.