"Illness, in the larger sense of mortality," Don Hardy writes, "is an inescapable shared trait among all living creatures, and we humans know about it, whether or not we want to talk about it." Because I'd Hate to Just Disappear is a portrait of a husband and wife, Don and Heather Hardy, thrown into the physical and emotional machinery of Don being diagnosed with leukemia and going through chemotherapy and treatment over a period of...