Concorde. Saturn V. Roman concrete. Humanity keeps forgetting how to build things.

In the 2000s, the United States tried to remake a secret material for its nuclear warheads. Nobody remembered how. The blueprints existed. The knowledge didn't.

Codename: FOGBANK.

Years of work. Tens of millions of dollars.

The answer was an impurity.

The original batches were contaminated, and the contamination made it work.

Nobody wrote it down. Nobody knew it mattered.

The list is long.

Concorde. London to New York in about 3.5 hours. Retired in 2003. Today the trip takes 7. We got slower.

Saturn V. The rocket that put humans on the Moon. Decades later, NASA engineers took apart an old F-1 engine to understand how it was built. The drawings survived. The people didn't.

Roman concrete. Harbors still standing after 2,000 years. Modern concrete starts cracking in decades. MIT only cracked the secret in 2023: lumps of lime that heal cracks when water gets in.

Damascus steel. Legendary blades. Recipe gone by the 1700s. Centuries later, scientists found nanostructures inside.

Greek fire. Burned on water. The recipe died with the few who guarded it.

Knowledge doesn't live in documents.

It lives in people.

People retire.

Your company has a FOGBANK.

The guy who knows why the server restarts every Tuesday.

The accountant who knows which client always pays late.

When they leave, it leaves with them.

The skill: write down the weird steps.

Not the official process. The weird steps.

"We always do X, nobody knows why."

That's usually the impurity.