It isn't easy to classify Charles Mingus.

He felt that way about himself, at least ethnically -- the multiracial Mingus observed that he felt like he belonged to several worlds, but was at home in none.

That's true musically, too, as Mingus straddled the line between classical composition and jazz improvisation.

After playing bass for innumerable jazz masters, Mingus forged out on his own, forming his long-lived Jazz Workshop in 1955. The group gave him the opportunity to work as a composer, carefully controlling the contributions of anywhere from four to 11 sidemen. But Mingus was a jazz man at heart, and his meticulous, sprawling constructions required improvisation, so he wrote parts that allowed such playing, often scrawling in the score's margins exhortations to jam.

This blend of orchestrated and improvisational music played by a large band was hardly new -- Duke Ellington was a master of that fusion. Even classical composers wrote room for improvisation into their works.

But Mingus' take on "orchestral jazz" was unique. One of the best examples is 1963's The Black Saint and the Sinner Lady, though it's not a good starting point for neophytes. (If you're new to Mingus, try the more accessible Mingus Ah Um or Pithecanthropus Erectus.) Black Saint is a vast, complex chunk of music, an emotional, impassioned magnum opus.

The whole thing is pinned down by a deep morass of tuba and trombone, with beautiful piano and horns floating above. Mingus' bass playing is lyrical as always.

Mingus combines elements of free jazz and avant-garde composition here, but throws in the other influences that matter to his music: gritty blues, soul and spontaneous, churchy gospel.

The Impulse reissue of Black Saint is outstanding -- wisely, it retains the original liner notes, divided between the ramblings of Mingus and the tangential observations of the psychiatrist who treated him at Bellevue.

A lot of Black Saint is pretty harrowing -- there's anger here, for sure -- but it's also beautiful, and ends on a note of ultimate hope. I'll leave it to the liner-note psychiatrist to explain what that means to the musician divided within himself.