The Essential Bill Monroe and the Monroe Brothers chronicles Monroe’s very first recordings from the late ’30s. Selecting 24 highlights, including nine selections from the Monroe Brothers, from the 60-plus tracks he recorded for Bluebird, The Essential is the best single-disc overview of the beginning of Monroe’s career and the roots of bluegrass, featuring such classics as “Mule Skinner Blues,” “In the Pines” and “Crying Holy Unto My Lord.” These are neither the best nor the best-known versions, yet they are historically invaluable, demonstrating the birthing pangs of bluegrass. – Stephen Thomas Erlewine