In Charles Rosenberg’s eyes, epidemics tell us a great deal about American society. Rosenberg, considered by many to be the nation’s pre-eminent medical historian, was recently named Professor of the History of Science at Harvard. Though many of Rosenberg’s works are well known, he is perhaps best known for his 1962 book, “The Cholera Years: The United States in 1832, 1849 and 1866.” The book is credited with influencing a generation of scientific historians to take a broader view and examine not just a disease and its victims, but society’s response to it, through politics, laws, and the social mores of the time. In his introduction to “The Cholera Years,” Rosenberg describes how looking at the three epidemics affords a view of three Americas. The different responses to the cholera outbreaks reflects the transition from a moralistic society that saw the disease as a judgment passed on society’s lowest elements to one more recognizable today, where the causes of the disease were better understood.