Martin Greenfield, the middle-aged professor in “A Teacher of the Holocaust,” enters into a romantic relationship with Rachel Klein, a therapist with children and a Holocaust survivor. Gradually, Greenfield confronts the unhealed wounds of the survivor and—more disturbing—the limits of his own compassion. In another story, Michael Arnold, returning to Jewish observance after an aimless life, fills his days with acts of loving kindness, and then makes a decision that costs him the wife he