Theory of the Four Humours

It is probably best to start by explaining exactly what the Theory of the Four Humours entailed.

The theory had first been put forward by the Ancient Greek physician Hippocrates. He had theorised that the human body contained four humours that controlled a person's personality and could affect their health.

Each humour corresponded to an element of nature: earth, air, water, or fire.

The four humours were:

Fig. 1 - A diagram showing the four humours and what they were associated with.

The Theory of the Four Humours Hypothesis

It is interesting to look at how people thought humours affected personality. The table below shows each humour, its corresponding personality type, and some positive and negative attributes.

Galen Theory of the Four Humours

Claudius Galen was born in Pergamum (modern-day Turkey) to Greek parents around 130 AD. He pioneered new forms of medical theory and practice, was a prolific writer, and was very well respected. He became the personal physician of Emperor Marcus Aurelius and his successors Commodus and Septimius Severus.

Fig. 2 - Preparation of theriac from the Tacunium Sanitatis, a 12^th-century medical text

Galen based his work on that of Hippocrates and developed humoral theory alongside his other medical discoveries. In particular, he created theriac - a remedy that would remain incredibly popular through the medieval era.

Medieval Theory of the Four Humours

The Theory of the Four Humours remained the dominant theory of medicine during the Medieval era. Although the ideas of Hippocrates and Galen were by now over a thousand years old, people still adhered to them.

The Church was the chief authority on medical matters in Medieval Britain. They copied and published nearly all books and written works until the invention of the printing press in the 1400s.

They published and disseminated the works of Galen and Hippocrates to train physicians. They allowed their work because it was trusted and did not contradict the Church's teachings.

The Theory of the Four Humours dictated how people were diagnosed and the available remedies. Physicians would diagnose an illness and then tell the apothecary what to make to cure the patient.

Renaissance Theory of the Four Humours

When the Renaissance occurred in Europe in the 1500s, the Theory of Four Humours remained central to medicine. However, other ideas and discoveries began to compete with it.

Here are some developments that affected the Theory of the Four Humours during the Renaissance.

The Printing Press

Johannes Gutenberg invented the printing press in Europe in the 1440s and revolutionised European society. In particular, the printing press allowed control of what was printed to move away from the Church and into the hands of the State and the people.

This meant that it was easier for new ideas about medicine to spread, regardless of whether the Church agreed with them.

Physicians: Vesalius, Paré, and Harvey

A few key figures who contributed to medicine and public health during the Renaissance and early modern era were Andreas Vesalius, Ambroise Paré, and William Harvey. Here is a brief list of their contributions.

• Andreas Vesalius: Vesalius made contributions to the field of anatomy. Becoming a university professor at the age of just 22, he advocated the use of medical dissections to learn about the human body. He published works with detailed drawings of human anatomy and proved some of Galen's theories about the body wrong.

• Ambroise Paré: Paré had been a surgeon in the French army for 20 years. This gave him a lot of experience in surgery, and, as a result, he came up with many new ideas about the practice. He proposed new ways for surgeons to treat wounds and amputations, including using ligatures to tie off blood vessels.

• William Harvey: Harvey was an anatomist like Vesalius, and similarly, he liked to use dissections to learn about the human body. His most important discovery was that of circulation. Whilst people understood that arteries and veins held blood, Harvey figured out how the circulatory system pumped blood around the body.

We can see that many new medical ideas appeared during the Renaissance. However, the Theory of the Four Humours remained a popular explanation for disease, despite the rise of medical understanding and publication.

Fig. 4 - William Harvey's diagram of the anatomy of the forearm

By 1700, physicians did not take the Theory of Four Humours seriously. However, it was still a common belief amongst the people.

The Theory of the Four Humours Overview

The Theory of the Four Humours was very influential for public health in medieval Britain. The idea of unbalanced humours making you ill dictated what people thought was good to eat and drink, where to go, and even your personality.

The Four Humours also controlled treatments for diseases in this period; as doctors saw the root cause of illness as unbalanced humours, treatments were centred around rebalancing them, whether with theriac or by bleeding and purging.

However, the Theory of the Four Humours did not do much to improve public health. While it was the theory about illness that people believed in, it was not correct. As a result, the public health issues that were causing the rapid spread of diseases like plague and leprosy were not properly addressed and fixed.