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Theory of the Four Humours

Theory of the Four Humours

The Theory of the Four Humours was a dominant medical theory during the Medieval era. It influenced the work of medical professionals and the way ordinary people thought about their bodies and health.

So, where did the Theory of the Four Humours come from, and how did it impact public health in Medieval Britain?

Summary of the 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:

HumourPersonality TypeAssociations
BloodThe "sanguine" humourAssociated with air and believed to be hot and wet.
PhlegmThe "phlegmatic" humourAssociated with water and believed to be cold and wet.
Yellow BileThe "choleric" humourAssociated with fire and believed to be hot and dry.
Black BileThe "melancholic" humourAssociated with earth and believed to be cold and dry.

Theory of the Four Humours Humourism StudySmarterFig. 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.

HumourPersonality typePositive attributesNegative attributes
  • Optimistic.
  • Social - has lots of friends.
  • Confident.
  • Impulsive.
  • Unpredictable.
Yellow BileCholeric
  • Ambitious.
  • Charismatic.
  • Short-tempered.
  • Dominating.
  • Irritable.
  • Dependable.
  • Calm.
  • Observant.
  • Lazy.
  • Resists change.
Black BileMelancholic
  • Kind.
  • Creative.
  • Perfectionist.
  • Quiet.
  • Often unhappy.

Prevalence of Humoral Theory

The impact of humoral theory spread into other areas of society apart from medicine. The influence of humours on personality was used to explain why groups of people were different to others and to construct behavioural norms based on whether you were a man or a woman, young or old.

Even though the humoral theory was disproved centuries ago, its influence can still be seen today. You might have heard of personality types and their tests, such as the Myers-Briggs Personality types. These tests have their roots in humoral theory!

Look at the table - which humour best matches your personality?

Origins - Hippocrates and Galen

Two key figures in the creation and development of the Theory of the Four Humours were Hippocrates and Galen.

Hippocrates Theory of the Four Humours

Hippocrates was an Ancient Greek physician who lived from approximately 460 BC to 370 BC. He is credited with creating the theory of the four humours and was hugely influential in Medieval medicine. Alongside his methods of clinical observation, his work on the Theory of the Four Humours formed the foundations of Medieval understandings of medicine, personality and the body.

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.

Theory of the Four Humours Theriac painting StudySmarterFig. 2 - Preparation of theriac from the Tacunium Sanitatis, a 12th-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.


This is a mixture of herbs, spices and other ingredients that were created by apothecaries to heal illnesses.

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.


This was a man, usually university-educated, who would diagnose illnesses and prescribe treatments. They did not perform surgery or create remedies.


This was someone who made and sold remedies to people. Patients could purchase the remedies if they felt they needed them or when a physician had prescribed them.

Here are some popular remedies based on the humoral theory that were commonplace during the Medieval era:

  • Phlebotomy (Bleeding): This involved a surgeon cutting into the skin or using leeches to drain blood from the body to rebalance the humours. However, doctors could take this too far, and people could die from blood loss.

  • Purging: This was done when a physician believed that someone had too much yellow bile in them. Food was thought to be used to create the humours, so a way of rebalancing them was to get the food out of your body. This would be done using an emetic, which would make the patient vomit, or a clyster, which would make them go to the toilet.
  • Theory of Opposites: This is linked to the first two remedies. Since the Theory of Four Humours dictated that illness was due to an imbalance of the humours, remedies would be created to rebalance them. For example, if a person had an excess of Phlegm, which was seen as cold and wet, the physician might prescribe a poultice of something hot and dry, like pepper or mustard seed.
  • Theriac: This was a mixture of ingredients, spices, and herbs believed to cure many minor illnesses. This was particularly popular as Galen himself had written about it.

Theory of the Four Humours Bleeding painting StudySmarterFig. 3 - Image of a patient being bled

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.

Did you know? The printing press reduced the influence of Hippocrates and Galen's ideas. It allowed a greater understanding of the basics of medicine - for example, better a understanding of human anatomy was made possible because of the ease of printing medical textbooks with accurate diagrams.

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.


This is the name for the structure of the body of a living being.


When a body is cut into and taken apart to study anatomy or find the cause of a disease.


A piece of material that is used to tie something up tightly. Ligatures were wrapped around a limb or a blood vessel to cut off the blood supply, easing surgeries such as amputations by reducing blood loss.

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.

Theory of the Four Humours Harveys anatomy StudySmarterFig. 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.

Did you know? The phrase 'a sense of humour comes from the theory of the four humours - specifically, the idea that humours could influence your personality!

Theory of the Four Humours - Key takeaways

  • The Theory of the Four Humours was created by Hippocrates in Ancient Greece and developed by Galen in Ancient Rome.
  • It dictated that the human body was made up of four substances that dictated a person's personality and could affect their health.
  • It was the dominant medical theory of the Medieval period.
  • Remedies were based on the theory of opposites. People would try to rebalance their humours by using bleeding, purging, or poultices.
  • The Theory of the Four Humours continued to be accepted during the Renaissance, even with the rise of new medical knowledge like that of Vesalius, Paré, and Harvey.
  • By 1700, the Theory of the Four Humours was no longer taken seriously by physicians but was still a popular explanation for disease amongst ordinary people.

Frequently Asked Questions about Theory of the Four Humours

This was a theory created by Hippocrates in which he theorised that the human body contained four humours that controlled a person's personality and could affect their health.

Hippocrates. It was later developed by Galen.

Hippocrates theorised that the body contained 4 humours which were affected by food and your environment, and influenced you personality and whether you would contract illnesses. In medical theory, it was thought that an imbalance of the humours would cause illness and disease, and so remedies were created to restore balance to the humours.

Hippocrates first developed the theory of the four humours when he lived between 460BC to 370BC. It was later developed further by Galen, who was born in 130AD.

The theory of the four humours fell out of favour with medical science after significant developments in the Renaissance. However, some modern tests, such as the Myers-Briggs personality test, has a basis in the four humours to determine personality types.

Final Theory of the Four Humours Quiz


Who first came up with the theory of the four humours?

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Which of these is NOT one of the four humours?

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Black bile.

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What natural system were the humours associated with?

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The elements.

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According to medieval medicine, which of these was influenced by the four humours?

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Which ancient physician developed the theory of the four humours and popularised it?

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Soranus of Ephesus.

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What popular medieval remedy did Galen invent?

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Who was responsible for disseminating the theory of the four humours in medieval Britain?

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The Church.

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If someone was diagnosed as having too much blood, what would a physician prescribe?

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Bleeding (Phlebotomy).

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If someone was diagnosed as having too much Yellow Bile, what would a physician prescribe?

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When did the theory of the four humours stop being accepted as a medical fact amongst the medically trained?

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18th century.

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