He poured the paint in layers and combed through it with an Afro pick. Or he froze and shattered it, reassembling the shards into new wholes. Like an alchemist, he altered its consistency with precisely calibrated tinctures. Like a hoodoo man, he infused it with ash, blood, and fragments of bone. His studio on Lispenard Street, in Tribeca, was full of contraptions, and his notebooks boiled over with a mad scientist’s exuberance. “TRUTH IS A PROCESS OF ELIMINATION” he exults in one entry; in another, a transformative residency at Xerox sparks an outburst of gospel: “I am on my way to glory / a child of the plane.” In the nineteen-nineties, he attained that glory with the invention of his “tesserae” paintings, arranging bits of hardened acrylic into glittering free-form mosaics. One called “Black Monolith II (For Ralph Ellison)” confronts you as you enter “The Messenger,” his new MOMA retrospective—a dark apparition checkered with iridescent squares, suggestive of a man’s silhouette, with a small razor where you’d expect a mouth.