The passage juxtaposes two of the most harmful myths of 19th century England: first, that bad smells spread disease (a misconception that probably caused thousands of deaths), and second, that poor people deserved their diseases because they were immoral in some vague way. In a sense, these two myths are manifestations of the same instinct: fear of the unknown. Thus many people, desperate for some explanation for the epidemic, convinced themselves that there was a method to the cholera’s madness: cholera spread in a certain way, or only killed certain people. This instinct to define, rationalize, and “tame’ the unknown is one of the most important themes of
The Ghost Map.