Then about 12 years ago it dawned on me that folk music -...

Then about 12 years ago it dawned on me that folk music - the music of Woody Guthrie and Phil Ochs, early Bob Dylan, Johnny Cash, Pete Seeger - could be as heavy as anything that comes through a Marshall stack. The combination of three chords and the right lyrical couplet can be as heavy as anything in the Metallica catalogue.