>>40602552 (OP)In Ancient Greece, depression was thought to be caused by a build-up of stagnant black stuff in the digestive system. They called this "melancholy" which literally means "black bile".
To clear out this buildup from the intestines, doctors would prescribe bitter herbs and laxatives.
These herbs were concocted into medicinal liquers, and they still exist today. In Europe they are called digestifs, or digestive bitters.
Some you may know: Absinthe, Angostura bitters, Vermouth
The main ingredients in these medicinal liquers are herbs such as fennel, anise, wormwood, mint, gentian, myrhh...
These ingredients are known to remove microbes and parasites from the digestive system.
And when this "black bile" is removed, the melancholy starts to disappear
Source: De Materia Medica - Dioscorides (70 AD)
https://www.loc.gov/item/2021666851/