Let its northernmost corner be Vicksburg, the famous, on the Mississippi. Let the easternmost be Mobile, and let the most southerly and by far the most important, that pivotal corner of the fan from which all its folds radiate and where the whole pictured thing opens and shuts, be New Orleans. Then let the grave moment that gently ushers us in be a long-ago afternoon in the Louisiana Delta. Throughout that land of water and sky the willow clumps dotting...