The jazz avant-garde has produced dozens of notable improvisers (not surprisingly, since improvisation is arguably the music's defining element) but relatively few great composers. Henry Threadgill is a member of that exclusive club. With his fellow Chicagoans Anthony Braxton and Muhal Richard Abrams, he's one of the most original jazz composers of his generation. Threadgill's art transcends stylistic boundaries. He embraces the world of music in its entirety, from ragtime to circus marches to classical to bop, free jazz, and beyond. This might sound merely eclectic in the tel...