Germ Theory

c. 1861 CE — Europe, France & Britain

Today: France (Paris) and Britain

Louis Pasteur demonstrated that invisible organisms caused fermentation and disease, and Joseph Lister applied the insight to surgery with antiseptics — replacing centuries of belief that illness came from bad air, imbalanced humors, or divine judgment. Doctors began washing their hands. Within decades, sanitation, vaccination, and clean water added more years to human life than any medical treatment before or since. Earlier plagues had been fought blind; from here, people knew what they were fighting.

Worth knowing: A Hungarian doctor named Semmelweis proved in the 1840s that handwashing slashed maternal deaths — and was ridiculed, dismissed, and died in an asylum. He was right about twenty years too early to be believed.

Pattern: Information-medium revolution — A new way to record or transmit information lowers the cost of copying ideas and reorders who holds knowledge and power.

Entry 196 of 240 in Precedent, a walk through the whole human story in order.