For a man whose take on folk music is so perpetually genial, Pete Seeger is still an American badass. In The Power of Song (Jim Brown’s documentary, airing as part of the American Masters series on PBS), octogenarian Seeger preaches a life of “?nding the right songs and singing them over and over,” but it’s his ideology that has de?ned him. Dylan, Springsteen, Seeger’s family and countless others testify, warmly and genuinely. Still living off-the-grid in a cabin he built in the late 1940s, the one-time Woody Guthrie disciple—responsible for introducing Martin Luther King Jr. to “We Shall Overcome”—glows like a sage warrior. Blacklisted from the airwaves and nightclubs when he told the House Un-American Activities Committee to bugger off in 1955, Seeger took to college campuses and classrooms with an indomitable spirit, almost single-handedly sparking the folk revival, the ’60s and life as we know it.