It was just another workaday gig for session musician Paul Harrington. He laid down a three-and-a-half minute harmonica line, never asking where it might end up. "So much of what you record never gets ...

Why do we love the harmonica? Why does it bring a crowd to life whenever a singer takes out the mouth organ and does a solo? I'm at the R.E.M. concert and they're playing the song "Bad Day." Michael ...