Drummer Art Blakey led many great editions of the Jazz Messengers from the inaugural mid-'50s sessions until his death in the '90s. While arguments rage regarding which was his best, there is no doubt that the 1960-1961 unit figures in the debate. This wonderful six-disc set, notated with care and painstaking detail by Bob Blumenthal, covers studio and live sessions from March 6, 1960, to May 27, 1961, with the same personnel on all but two songs. Producer Michael Cuscuna used only first issue dates, and while he included some alternate takes, he did not litter the discs with second-rate vault material. They smoothly detail the band's evolution, cohesion, and maturation. This set, as with all Mosaic boxes, goes beyond essential. Get it post haste.