Sorrow is "not a state but a process" that needs "not a map but a history. . . . There is something new to be chronicled every day," writes C. S. Lewis in A Grief Observed. When Carl Klaus's wife of thirty-five years died suddenly from a cerebral hemorrhage, right before Thanksgiving in 2002, he took the only road toward recovery that made sense to him: he started writing letters to her, producing a unique history of grief, solace, and love. His vivid...