This was such a great read. Steven Johnson chronicles the investigations of John Snow and Henry Whitehead in the cholera outbreak in London in the mid-19th century. Their work first identified cholera as a water-borne disease and was one of the earliest epidemiological studies ever conducted. The book is both an interesting story of the cholera outbreak, and a frustrating example of the perils of superstition and bad science.

At the time, the medical/scientific community believed that diseases were transported by smells and odors in the air, and that there was something in the moral character of the poor that made them susceptible to disease. John Snow, a doctor, and Henry Whitehead, a clergyman, both were anomalies in that they didn't see the outbreak through this distorted lens. As such, they were able to do extensive research into the real reasons behind the outbreak, and trace the origins of the cholera outbreak to its patient zero and the source. Johnson traces this process from the beginning of the outbreak, to the Snow/Whitehead conclusions and through to the far-reaching implications on modern urban life.