If one company embodies jazz's aesthetic and its curious relationship to the music industry, it's Blue Note. Cook, a coauthor of The Penguin Guide to Jazz on CD, lingers with record-collector zeal in analyzing everything from Sidney Bechet's 78s to Norah Jones' recent chart-topper. Yet this is no buyer's guide: Billed as a biography, it details how two ambitious German fans of ''hot jazz,'' Alfred Lion and Francis Wolff, founded the label in 1939 and then played a major role in all that followed. Insightful scenes abound: the original 4:30 a.m. studio sessions (musicians loved them); Lion's late-'40s championing of a then-misunderstood Thelonious Monk; the birth of Art Blakey's hard bop; and more. In addition, Cook leavens the book with dry wit, describing jazz's core audience as a ''motley, disenfranchised gathering.''