In the '50s, the party line among New York jazz critics was that hard bop was the "true faith" and that cool jazz was lightweight and unemotional. But Miles Davis knew better. The trumpeter (whose Birth of the Cool sessions of 1949-1950 proved to be incredibly influential) was smart enough to realize that cool jazz and hard bop were equally valid parts of the house that Charlie Parker built, and he had no problem working with cool jazzmen one minute and hard boppers the next. Recorded for Charles Mingus' Debut label in 1955, Blue Moods is an excellent example of cool jazz.