This collection catches up with Johnny Cash right after his Sun Records rockabilly period. He moved over to Columbia at the tail end of the 1950s, just when the initial salvo of rock & roll was dying out, responding to their promise of creative freedom. The mostly-'60s hits included here find him embracing that freedom, perhaps nowhere as tellingly as on "Ring of Fire", the June Carter/Merle Kilgore-penned gem in which surreal biblical imagery meets mariachi trumpets in an unlikely but brilliant production. Cash acknowledges the '60s folk boom with covers of Dylan's "It Ain't Me, Babe" and Pete La Farge's American Indian protest song "The Ballad of Ira Hayes". An anti-violence message is portrayed with a minimum of didacticism and a maximum of organic poetry on "Don't Take Your Guns to Town". Columbia's GREATEST HITS provides an excellent guide through Johnny Cash's '60s.