by WALKER PERCY
257 pages. Farrar, Straus & Giroux.
Although he has been called a novelist of ideas, Walker Percy, 60, is less a philosopher than a physician to the public weal. Tuberculosis prevented him from using the M.D. he earned in 1941, but The Moviegoer (1962), Percy's first novel and a National Book Award winner, demonstrated his remarkable diagnostic skill. In it and two later novels, he specialized in asking probing questions: Why are people with every outward trapping of happiness so miserable? Where and why does it hurt?