The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World

by Steven Johnson

without efficient forms of waste recycling, those dense concentrations of life can’t survive for long.

Without the bacteria-driven processes of decomposition, the earth would have been overrun by offal and carcasses eons ago,

If some rogue virus wiped out every single mammal on the planet, life on earth would proceed, largely unaffected by the loss. But if the bacteria disappeared overnight, all life on the planet would be extinguished within a matter of years.

the average London household used 160 gallons of water a day in 1850.

“There is no document of civilization that is not also a document of barbarism.”

In terms of professions, tailors outnumbered any other trade by a relatively wide margin. After the tailors, at roughly the same number, were the shoemakers, domestic servants, masons, shopkeepers, and dressmakers.

(Plagues and political unrest have a long history of following the same cycles.)

“Mind you, the man who is in the minority of one is almost sure to be in the right.”

epidemics create a kind of history from below: they can be world-changing, but the participants are almost inevitably ordinary folk, following their established routines, not thinking for a second about how their actions will be recorded for posterity.

it makes for good museum copy to talk about an Age of Dinosaurs or an Age of Man, but in reality it’s been one long Age of Bacteria on this planet since the days of the primordial soup. The rest of us are mere afterthoughts.

The organism effectively converts the human body into a factory for multiplying itself a millionfold.

human blood has almost the same concentration of salts as seawater.

“Those animal species that fully adapted to the land did so through the trick of taking their former environment with them,” the evolutionary biologist Lynn Margulis writes.

“No animal has ever really completely left the watery microcosm…. No matter how high and dry the mountain top, no matter how secluded and modern the retreat, w...

We sometimes talk about organisms “desiring” certain environments, even though the organism itself surely has no self-awareness, no feeling of desire in the human sense of the word. Desire in this case is a matter of ends, not means: the organisms wants a certain environment because the setting allows it to reproduce more effectively than other environments: a brine shrimp desires salty water, a termite desires rotting wood.

In environments where the risk of transmission is low, the better strategy is to pursue a low-intensity attack on the human host: reproduce in smaller numbers, and keep the human alive longer,

we now live in a society where image is valued over substance, where our desires are continually stoked by the illusory fuel of marketing messages. In a real sense that condition dates back to those now quaint notices running in the columns of Victorian newspapers, promising an endless litany of cures bottled in one marvelously inexpensive elixir.

The constant squabbling between medical authorities in the papers eventually hit a point of self-parody.

Temperamentally he was not the cliché of the friendly, garrulous general practitioner; his bedside manner was taciturn and emotionally flat.

But he was a superb doctor: observant, quick-witted, and possessed of an exceptional memory for past cases.

Snow was as free from superstition and dogma as it was possible ...

what drove him, more than anything, were problems that needed solutions, filling in the blind spots in the medical establishment’s vision of the world.

There is something wonderful—and more than a little ironic—in this image of Snow the teetotaler, arguably the finest medical mind of his generation, performing his research. He sits alone in his cluttered flat, frogs croaking around him, illuminated only by candlelight. After a few minutes tinkering with his latest experimental inhaler, he fastens the mouthpiece over his face and releases the gas. Within seconds, his head hits the desk. Then, minutes later, he wakes, consults his watch through blurred vision. He reaches for his pen, and starts recording the data.

the most impressive thing about his research was not the levels of social class that he traversed but rather the intellectual strata, the different scales of experience that his mind crossed so effortlessly. Snow was a truly consilient thinker,

Snow’s work was constantly building bridges between different disciplines,

Snow was not interested in individual, isolated phenomena; he was interested in chains and networks, in the movement from scale to scale.

A better sort of people lived on the ground floors—no wonder they were more likely to fight off the disease.

But not because the sewers had disturbed a three-hundred-year-old graveyard.