“On Witness and Respair,” by Jesmyn Ward, Scribner, 256 pages. Jesmyn Ward remembers seeing the Mississippi Literary Map on the wall of her elementary school library. Iconic names and faces — Faulkner, Welty and Wright — staring out from the confines of a state that might have then ranked last in the nation among most childhood education and well-being indicators but punched above its weight when it came to literature.