Medicine 3: Which other *old idea* about the cause of illness mostly *faded* away by the end of the 18th century?

Question

Which other *old idea* about the cause of illness mostly *faded* away by the end of the 18th century?

Happy Bat · Accepted Answer

People still believed in *miasma* to some extent, but this was becoming *less popular* by the end of the 18th century

Which other old idea about the cause of illness mostly faded away by the end of the 18th century?