It was a dark Sunday—yes, yes, a black Sabbath—for lovers of music in two schools that have nothing whatsoever in common except for the fact that a pair of artists revered in their spheres, the heavy-metal singer Ronnie James Dio and the jazz pianist Hank Jones, died on the same day: May 16, 2010. I'm not suggesting an act of music-savvy gamesmanship by the Reaper, a band call to the great venue in the sky. Besides, Dio and Jones would have been summoned by contractors in different jurisdictions of the musicians' afterlife—Dio to the hell he sang about with demonic ardor, Jones to the heaven he suggested in his elegiac improvisations. Dio and Jones are worth considering in mutual context because each of them clarifies the values of the other, by negation. They are near opposites, aesthetically.

More interestingly, I think, each of them defied misconceptions of their music held by the other one's audience. Dio, in the operatically menacing performances he gave with Black Sabbath (in which he succeeded Ozzy Osborne as lead singer) and his self-named band Dio, embodied stagy excess.

Jones, in the elegant, disciplined playing he did with Art Farmer, Charlie Haden, Joe Lovano, and many others over his seven-decade career, personified sly restraint.

What Jones's admirers would probably not suspect about Dio is that his style requires exceptional technique—range and power, especially. In fact, music like Dio's is all about the histrionic display of technique (and codpieces). And what Dio's fans would probably never suppose about someone like Jones is that the jazz he treasured is all about emotional expression, rather than the display of virtuosity. While Dio boomed at his audiences to stand up and shout, Jones suggested that his should sit back and keep quiet, and neither message was as easy to get across as it looked.