Johnson is fascinated about how great ideas come to fruition and is a keen advocate of the theory that the big breakthroughs often come on the back of smaller ones. the concept of a single genius enjoying their light bulb moment is more of a fiction.
The same is here with it taking the efforts of John Snow and Rev Henry Whitehead to crack the cause of the cholera epidemic that ran through Soho in 1854.
Most people have a rough idea of what happened with Snow discovering that it was the drinking water that was the source of the disease and getting the pump shut off that had been spreading cholera.
But getting to that point took a long time and Snow was going against the consensus that diseases like Cholera were airborne.
What clinched the argument for Snow was his dedication in mapping the spread of the disease and finding the Broad Street pump had been the common link. But it also took the efforts of Whitehead, who initially disagreed with Snow and set out to disprove his theory. As he worked hard to counter the waterborne theory he managed to reinforce it by knocking down his own objections. It was Whitehead who found the original cholera case and traced how it found its way into the water supply.
The legacy of Snow's efforts were profound not just in the sense of linking cholera to water supply but also the way he mapped the spread of the disease. His Ghost Map is something that has been mimicked ever since and helped change the way scientists visualise data.
This is a story of the hard working hero plodding around the streets of Soho after working all day as a doctor fighting the establishment to find the real cause of the cholera outbreak.
It is a story well told but my only criticism is the sense of repetition of the main arguments. I got it the first time but there seems to be a fear from the author that unless he really spells it out the main points might be missed.
But that is a minor criticism because overall this book manages not only to share the story of what happened in 1854 but also the legacy. Snow's techniques combined with the internet, social media and the latest mapping techniques are being used right now to save lives. That is a profound legacy that has lasted well beyond the original cholera outbreak.