By now Munro can do with the short story whatever she wishes, and get away with it. She can paraphrase old bad poems ("Meneseteung") and in-fold a slight story about burial at sea ("Goodness and Mercy") so that, when opened up, the result is a masterly revision of Chekhov's masterpiece "Gusev." So much particularized life is packed into her every story that for her just to nudge these pieces causes glacially significant movement. Here, that movement most impressively is about sex--adulterous sex experienced by otherwise contentedly married women. In "Five Points," a married woman takes from her lover the honor of sex, a network of feeling like the "underground system that you call 'dreams'. . .all coiling and stretching, unpredictable but finally familiar. . ." To another, in "Oh, What Avails," adultery--"her sustaining secret"--means the continuance of her married life, "and in order to continue it she must have this other. This other what? This investigation--to herself she still thinks of it as an investigation." Adultery brings suffering aplenty in the stories, but it is only another kind of suffering in the weft of marriage. Forgiveness born of knowledge is the air of Munro's fiction: the husband, in the best story here, "Oranges and Apples," considers his wife's excessively colorful clothing and thinks: "He was willing to see all sorts of difficult things about Barbara--her uncharitableness, perhaps, or intransigence--but nothing that made her seem a little foolish, or sad." Generosity is squeezed from life's crowding. Munro's finest collection yet.