What if we hadn't heard that! was Tracy's summary after an evening at the Academy of Music in PHL with Herbie Hancock and Chick Corea. These masters, with so much shared history (Miles Davis, fusion . . .) but such individual sounds, found common ground and gave a couple thousand of us the music lesson of a lifetime. The opening 10-minute atonal improvisation transported the audience, proved that any resistance to non-tonal / non-modal harmony is past, threw off enough original ideas to spawn 1,000 more pieces, and showed how two minds can merge and expand in kind of a square function. Is there another art form where that is possible?