Waiting for the Barbarians, by J. M. Coetzee. New York: Penguin Books. 156 pp. $3.95.
In an unnamed ''outpost'' far from the center of ''the Empire'' it serves, a magistrate, also nameless, broods over repressive practices he condones and helps administer. ''I never wished to be drawn into this,'' he tells himself, while complying as innocent fishermen and nomads are rounded up and interrogated: The Empire fears attack from ''the barbarians,'' and every stranger must be suspected. The magistrate takes in a crippled, blind ''barbarian girl'' who becomes the center of his life, the cause of his loss of power, public humiliation, and eventual outsider's status. He waits, as we do, for the promised final catastrophe, and the revelation of who the barbarians really are. Obviously allegorical, this short, spare battering-ram of a novel by a white South African writer resonates with both local and universal suggestiveness. Its criticisms of official injustice and paranoia do not completely avoid didacticism and stridency, but Coetzee's mastery of first-person narration and blunt accusatory plain prose and his creation of convincing atmospheric detail make the novel a powerful and disturbing reading experience.