A sidewalk chalkboard sign advertises Botox, fillers, and facial treatments in Lafayette, California, on

May 21

, 2025. | Smith Collection/Gado/Getty Images

In the early 1800s, in southwestern Germany, outbreaks of a mysterious illness spread throughout the countryside.

People who came down with it had terrible symptoms. Their eyelids would droop.

Their speech would slur. They’d be gripped by a paralysis that, once it reached their breathing muscles, could be fatal.

A young doctor named Justinus Kerner was called in to investigate.

Kerner had decided to go into medicine after he awoke from a prophetic-feeling dream to find that a paper prescription from a nearby hospital had wafted in through the window while he was sleeping. He took it as a sign.…