The “Man in Black” tag doesn’t just reflect Johnny Cash’s moody sartorial bent; it captures the dark outsider mythos suffusing his songs. “Folsom Prison Blues,” “I Walk the Line,” “Big River”—these are universal anthems of rebellion forged of alienation, heartache, and poverty. So universal, in fact, that Cash has been covered by artists of every stripe: Bruce Springsteen, U2, Bob Dylan, and Nick Cave have all channeled the icon’s outlaw poetry.