Plagues offer a peculiar light on the ways human deal with being helpless. Many other types of disasters happen more suddenly: when there is a devastating earthquake, hurricane, or volcanic eruption, catastrophe often arrives so quickly and forcefully that there is very little time to do more than the instinctual response, and only in retrospect do people find themselves with time to contemplate how they might have prepared and responded. These events involve forces which a human cannot hope to control, even if they can be understood. In war, situations are often much more protracted for the majority of participants, and there is a very real sense that one’s survival depends on one’s capacity and actions. Events usually move slowly enough that there is plenty of room to contemplate death and suffer in anticipation of death. A serious plague combines some of the worst aspects of either of these kinds of tragedies: it moves slowly enough to give a person time to think about the future,...