I had the distinct honor of being asked to write an essay for the recent release of Steve Earle’s extraordinary post-1995 songbook, when he came roaring back from addiction and a brief incarceration to reassert himself as one of our most relevant songwriters. Yes, Steve is at this point a friend and colleague, having worked with us on “The Wire” and “Treme” both. But I’d’ve written what follows if I had only the music itself on which to rely. For those who have not yet savored Mr. Earle and his work, the new boxed set, “Steve Earle: The Warner Brothers Years,” which includes audio and video live performances from that period as well as three essential studio recordings, is a perfect entry point into what has become an extraordinary canon of American roots music. * * * I am generally down on the idea of heroes. We have enough of them in American culture, certainly, yet we are always in the process of tearing some...