How The Louvin Brothers' 'Satan Is Real' and 'Tragic Songs of Life' Shaped Keith Richards' Vocal Arrangements on 'Sweet Virginia' and 'Torn and Frayed'

During the loose, boozy Exile on Main St. sessions at Keith Richards’ Villa Nellcôte in 1971, Richards kept two Louvin Brothers albums spinning on the turntable: Satan Is Real (1959) and *