The Four Humors

Lesson Transcript
Instructor: Devin Kowalczyk

Devin has taught psychology and has a master's degree in clinical forensic psychology. He is working on his PhD.

When we talk about the 'four humors,' we unfortunately are not referring to comedy. Humors are fluids that ancient physicians believed control a person's temperament, personality, and health. Updated: 02/08/2021

Quick History of the Four Humors

Despite the name, the four humors have nothing to do with clowns and comedy clubs. Humors were thought to be fluids found in the body and were said to influence health, disease, temperament, and personality. Many philosopher-medicine men examined the different fluids that could come out of a person and drew conclusions about the fluids being involved with disease. This thought process is partially right, but mostly wrong.

Many ancient civilizations noted a connection between bodily fluids and illness. You probably have, too. For example, if someone has snot running from their nose, are they sick or are they well? If someone has a very red face because the blood has rushed there, are they angry or sad?

The first record of someone creating a comprehensive system of bodily fluids was by a Greek physician by the name of Hippocrates. You may have heard doctors refer to him in the form of the Hippocratic Oath. Hippocrates was a contemporary of Plato, and many of Plato's works reference Hippocrates' work.

Later on, a Roman named Galen would add to Hippocrates' work. While Hippocrates focused on health and disease connections to the humors, Galen would add to it by connecting a person's temperament and personality to imbalances in their humors. This will be explored in more detail when we look at the individual humors.

Broadly defined, humorism is the belief that the body is influenced by four fluids produced by organs in the body. The four fluids are:

  1. Blood
  2. Phlegm
  3. Black bile
  4. Yellow bile

Each humor would increase and decrease depending on many factors, such as what you eat, the time of year, the temperature, your gender, and the time of day. If a person had an excess or an insufficient amount of a humor, this would lead to an imbalance, and there would be a predictable change in the ill person. We will break this up humor by humor.

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  • 0:04 Quick History of the…
  • 1:59 Blood
  • 3:16 Phlegm
  • 4:36 Black Bile
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This is the blood inside your veins and arteries. This humor can also be referred to as sanguine, which is derived from Latin and means to deal with blood. According to Hippocrates, blood was exclusively produced by the liver. This is actually the site where blood is cleaned, as we now know blood is produced in the red marrow of the long bones.

Blood production was linked to spring and summer, where people were thought to have an excess amount of blood because of their red complexions. But why else would a body push all of that hot blood near the surface then start to sweat? It may be that during the summer months before air conditioning was invented, the body put the blood near the skin and then produced sweat to cool off. This may be why the blood humor was linked to hot and moistness in ancient times.

According to Galen, if a person had excess blood, they would be described as sanguine. If you had a sanguine personality, you would be sociable, charismatic, and a constant day dreamer. This may be because people who have jovial tendencies can have a ruddy or red complexion.

Excess blood was easy enough to treat. A physician would practice bloodletting, or allowing a certain amount of blood to be released from the body. Modern research into this technique has found no real benefits.


Phlegm, that nasty stuff you get in your throat after drinking something cold or when you are sick, was another humor. Obviously the phlegm humor was associated with cold and dampness. The season associated with phlegm is winter. When you put all of this together, it makes a certain level of sense; that is, if you don't take modern biology into account. In the winter it's cold, so you may have some phlegm in the morning if your mom forgot to turn up the heat the night before. In the winter, while it's cold and damp, people get sick and have even more phlegm. Obviously, it must be the phlegm causing the illness!

Treatment would be to avoid cold foods and drinks, which can cause an increase in phlegm. The model also predicts that the brain is the major producer of phlegm, which also makes sense because it floats in a clear, mucus-like fluid known today as cerebrospinal fluid.

Galen labeled people who had excess phlegm as phlegmatic. A person who is phlegmatic is described as quiet, relaxed, and sluggish. When you're sick you don't feel well, so you lay in bed to get better. If you looked in through the window and saw this person with excess phlegm laying in bed, not talking much because he is sick, you may describe him as relaxed, lazy, sluggish, and quiet. Again, science aside, this stuff makes a certain level of sense.

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