‘Humorism' was the system of medicine developed by the likes of Hippocrates, which holds that the human body is composed of four substances: black bile, yellow bile, phlegm, and blood. The balance of these ‘humors' determines our health, while disease and disability supposedly result from an excess or deficit of one or more.

Humorism dominated Western medical thinking for around 2,000 years from when it was first systematised in around 400 BC. Regardless, it was passed on through the generations despite any evidence the application of bloodletting, emetics and purges cured anybody.