Miasma theory
This was the idea that miasma (bad air) is responsible for disease. Prior to the introduction of germ theory in the late 1800’s, this was the most widely accepted explanation for why people got sick. The results of this theory led to some rather interesting medical solutions. During the Middle Ages doctors would prescribe “fart smelling.” Apparently it was believed that like cures like, and if bad air caused the disease…bad air could cure it.