"I'm not a working musician," the legendary Canadian jazz guitarist Sonny Greenwich once declared. "When I decide to play, I play to awake people spiritually. That's the only reason." For that, and for his stirring, distinctively linear style, he was hailed in 1970 as "the Coltrane of guitar players." In truth, though, Greenwich made music entirely on his own transcendent terms in the course of an uncompromising 50-year career...