So this was the state of London in 1854, and in the middle of all this carnage and offensive conditions, and in the midst of all this scientific confusion about what was actually killing people, it was a very talented classic 19th century multi-disciplinarian named John Snow, who was a local doctor in Soho in London, who had been arguing for about four or five years that cholera was, in fact, a waterborne disease, and had basically convinced nobody of this.