“And so the ghosts of the Broad Street outbreak were reassembled for one final portrait, reincarnated as black bars lining the streets of their devastated neighborhood. In dying, they had collectively made a pattern that itself pointed to a fundamental truth, though it took a trained hand to make that pattern visible.”

The ghosts dotting Dr. John Snow’s map were victims of a devastating cholera epidemic in Victorian London. Dr. Snow keenly observed, with the help of a local curate, that the disease was waterborne – quite contrary to the miasma theory of disease dominating medicine at the time. 

Public officials were slow to accept this theory, but this outbreak ended up being a catalyst for modern urban sanitation as we know it. Steven Johnson skillfully chronicles this outbreak and how it shaped modern medicine and urban development in The Ghost Map: The Story of London’s Most Terrifying Epidemic and How It Changed Science, Cities, and the Modern World.

The more I read about the past, the more grateful I am for the present. Once again I’m reminded that luxuries like modern plumbing, sanitation, and medicine are not to be taken for granted! Unfortunately, cholera is not confined to the past, still infecting portions of the globe. At least now we understand it.