This four-disc, 68-track collection paints a broad definition of the blues, with cuts ranging from vintage country blues (Robert Johnson's “Cross Road Blues,” Son House's “Death Letter Blues”) to uptown jazz blues (Nina Simone's “Blues for My Mama,” Billie Holiday's “Billie’s Blues”), Chicago blues (a live version of “Howling Wolf” by Muddy Waters), British blues (Jeff Beck's “JB’s Blues”), and contemporary acoustic blues (“Am I Wrong” by Keb' Mo'), with plenty of stops in between, making for a random but varied playlist that circles the different approaches and musical definitions of the genre.