Without the New Grass Revival, there would be no Alison Krauss + Union Station or Nickel Creek. From their founding in 1971 to their disbanding in 1989, New Grass Revival were always ahead of the game, building on the progressive sensibilities of veteran bluegrass popularizers such as Earl Scruggs and Jim & Jessie and taking the genre into relatively uncharted territory. Melding the ancient tones to rock, jazz, country, reggae, and gospel, they forged a link between the past and present as they hurtled toward the future. The journey began with founder and mandolinist/fiddler extraordinaire Sam Bush abetted by Courtney Johnson (banjo), Curtis Burch (guitar), and Harry Shelor (a.k.a. Ebo Walker, on bass); when Walker bowed out, he was eventually replaced by the formidable bassist/vocalist John Cowan; in its latter years, when Johnson and Burch hung it up, the lineup was bolstered by guitarist Pat Flynn and banjo visionary Béla Fleck. In all configurations, the New Grassers were fearless and eminently entertaining; this double-disc, 35-song career retrospective shows how and features seven previously unavailable live cuts (including three from the band's final show, on New Year's Eve, 1989) and three newly unearthed studio cuts. For an idea of this band's advanced sensibility, check out the shifting textures and instrumental dialogue of the dazzling toe-tapper "Spring Peepers." Or the banjo-fired, red-hot workout of the Beatles' "I'm Down." For a change of pace, consider the cool harmonies and the relaxed, stripped-down arrangement fueling Bob Marley's "One Love." And John Cowan's blue-eyed soul wailing on a propulsive treatment of "Ain't That Peculiar" would surely get Marvin Gaye's nod of approval. Truth be told, the time is still right for New Grass Revival. Come on back, fellas.