THE BOOK OF HRABAL by Peter Esterhazy (Northwestern U. Press: $22.50; 168 pp.) “The Good Lord was omnipotent,” Peter Esterhazy confirms. “There was one thing, though, he could not do, he could not play the saxophone. Offhand it would be hard to say why.” Incidentally, God hires the late but ever irreverent Charlie Parker to teach Him. This is a Catherine wheel of a novel, sparks in every direction. At times, on whim, Esterhazy tames his tiger, trying to tether the tale to a tragedy, but a natural verbal exuberance invariably prevails. There is a plot. God knows. Anna is determined to abort her fourth child. The Lord sends two slightly scuffed angels to dissuade her: Blaise and Gabriel, a.k.a. Cho-Cho. They stake out the digs of Anna and her husband, a writer obsessed to the point of block by a biography of fabled Czech storyteller Bohumil Hrabal.