When [Charlie] Chaplin began to talk on-screen, he used a cultivated voice and high-flown words, and became a deeply unfunny man; if he had found the street language to match his low-life, tramp movements, he might have been something like Richard Pryor, who's all of a piece—a master of lyrical obscenity. Pryor is the only great poet satirist among our comics. His lyricism seems to come out of his thin-skinned nature; he's so empathic he's all wired up. His 1979 film "Richard Pryor Live in Concert" was a consummation of his years as an entertainer, and then some. He had a lifetime of material at his fingertips, and he seemed to go beyond himself. He personified objects, animals, people, the warring parts of his own body, even thoughts in the heads of men and women—black, white, Oriental—and he seemed to be possessed by the spirits he...