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

by Steven Johnson

We feel fear more strongly because our safety expectations have risen so dramatically over the past hundred years.

The first defining act of a modern, centralized public-health authority was to poison an entire urban population.

So often what is lacking in many of these explanations and prescriptions is some measure of humility, some sense that the theory being put forward is still unproven.

Whenever smart people cling to an outlandishly incorrect idea despite substantial evidence to the contrary, something interesting is at work.

The river of intellectual progress is not defined purely by the steady flow of good ideas begetting better ones; it follows the topography that has been carved out for it by external factors.

This is how great intellectual breakthroughs usually happen in practice. It is rarely the isolated genius having a eureka moment alone in the lab. Nor is it merely a question of building on precedent, of standing on the shoulders of giants, in Newton’s famous phrase. Great breakthroughs are closer to what happens in a flood plain: a dozen separate tributaries converge, and the rising waters lift the genius high enough that he or she can see around the conceptual obstructions of the age.

It’s not that the world is changed instantly; the change itself takes many years to become visible. But the change is no less momentous for its quiet evolution.

He had no medical training, no background in public health. His only credentials for solving the mystery behind London’s most devastating outbreak of disease were his open and probing mind and his intimate knowledge of the community.

You could leave town for a weekend and come back to find ten percent of your neighbors being wheeled down the street in death carts. That was life in the big city.