BLACK BOX <i> by Amos Oz; translated from the Hebrew by Nicholas De Lange (A Helen and Kurt Wolff Book/Harcourt Brace Jovanovich: $21.95; 243 pp.) </i>

The matrimonial love-hate triangle that provides the novel’s ostensible subject also stands for the unresolved question that troubles and divides thoughtful Israelis over their nation’s character and destiny.