Theories in Medieval Medicine and Science - The Four Humours

When it came to people's health, medieval medicine and science were, in a word, inaccurate. There were several prevailing beliefs that dominated the discipline of medicine, most of which had very little actual medical value.

Ancient Medicine and Science

One of the main theories of medieval medicine and science was that of the Four Humours, which was probably first theorised by Hippocrates around 430 BC and further developed by Aristotle around a hundred years later.

Some of the knowledge left over from the classical world survived and was treated as 'gospel', as new knowledge was hard to come by. This was largely due to the fact that cannon law forbade the practice of dissection, which was considered sacrilegious. Much of the medical knowledge that was used was therefore obtained from philosophy and ancient knowledge; Hippocrates stated in his work 'On the Constitution of Man',

"Man's body has blood, phlegm, yellow bile and black bile. These make up his body and through them he feels illness or enjoys health. When all the humours are properly balanced and mingled, he feels the most perfect health. Illness occurs when one of the humours is in excess, or is reduced in amount, or is entirely missing from the body".

These liquids were also thought to be connected to a person's personality, one of the elements and had combinations of heat and moisture, all of which had to be in perfect balance for the body to remain healthy. The various parts of the humours were grouped together as follows;

Personality Types



yellow bile
black bile


hot & moist
hot & dry
cold & moist
cold & dry



How Medieval Medicine and Science Treated Imbalances to the Humours

There were various methods according to medieval medicine and science knowledge applied to bring the four humours back into a state of balance when somebody became sick. The favourite methods amongst doctors included bloodletting, intestinal purging and inducing vomiting; none of these methods were very effective and all of them can sometimes actually be harmful to the patient.

Luckily for the people of the middle ages, the placebo effect would bring some success in these treatments just because people believed they would work. Even today, it is estimated that up to a third of all healing takes place as a result of placebo, unfortunately for the other two thirds of medieval patients, healing needs some good science which was mostly lacking at the time.

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