The joy of tracing Janis Joplin's inspirations lies in the lines she blurred between genres and sexuality. She echoes the deep well of Odetta's rib-rattling wail and Otis Redding's sweat-flecked moan. She borrows Big Mama Thornton's throaty swagger and Aretha Franklin's sassy soulfulness. And the blues was at the heart of all her work, whether it was Leadbelly's guttural growl or Ruth Brown's powerful howl.