Historian of Science Thomas Levenson — How Humans Discovered Germs

• Miasma theory was appealing because it explained disease via 'bad air' linked to filth and decay, fitting both secular and religious views. - It persisted because it was flexible, mechanistic, and seemed to fit observations reasonably well.

Germ theory revolutionized how we understand and combat infectious diseases by identifying microbes as the cause, replacing older ideas like miasma theory which blamed "bad air."

For centuries, the presence of microbes was seen as a curiosity, not connected to disease due to prevailing cultural beliefs like the Great Chain of Being, which placed humans above microbes socially and spiritually. This conceptual framework blocked early scientists from linking microbes to illnesses.

The story includes key figures like Antony van Leeuwenhoek, who first observed microbes in pond water, and Ignaz Semmelweis, whose handwashing intervention drastically lowered deadly childbed fever but faced rejection due to social hierarchy and medical norms.

Louis Pasteur's work, including showing microbes spoil food and identifying disease-causing bacteria, solidified germ theory, leading to vaccines and hygiene improvements that transformed public health. Despite the progress, modern society risks losing these hard-won lessons as vaccine skepticism rises.

• Antony van Leeuwenhoek was an amateur Dutch cloth merchant who used microscopes to discover a vast unseen microbial world in pond water around 1676. - He sent detailed descriptions and drawings to the Royal Society that fascinated but did not link microbes to disease.