We are enthralled and fascinated by the process as invention from accretion and accumulation, yet too often we hear a great deal of “aiming,” which fixes the music, with the ironic dialectic of its method, as somewhat “aimless.” Improvisation is the heart of the music, expressing variations on some thematic focus, which then links them as a “symmetrical” or logical (aesthetic not geometric) whole. Without this contrast and resulting “tension,” the “wholly” spontaneous coheres as overly formal, or unconnected and meandering. This is the shape of Sabir Mateen’s work on Mad. Full of energy and desire, without the wholeness or interior rationale of clear, riveting aesthetic cohesion. He’ll get there.