Humorism, or humoralism, was a theory of the makeup and workings of the human body adopted by ancient Greek and Roman physicians and philosophers. From Hippocrates onward, the humor theory was the most commonly held view of the human body among European physicians until the advent of modern medical research in the nineteenth century.
Essentially, this theory held that the human body was filled with four basic substances, called four humours, or humors, which are in balance when a person is healthy. All diseases and disabilities resulted from an excess or deficit of one of these four humors. The four humors were identified as black bile, yellow bile, phlegm, and blood. Greeks and Romans, and the later Western European medical establishments that adopted and adapted classical medical philosophy, believed that each of these humors would wax and wane in the body, depending on diet and activity. When a patient was suffering from a surplus or imbalance of one fluid, then his or her personality and physical health would be affected. This theory was closely related to the theory of the four elements: earth, fire, water and air - earth was predominantly present in the black bile, fire in the yellow bile, water in the phlegm, and all four elements were present in the blood.
Theophrastus and others developed a set of characters based on the humors. Those with too much blood were sanguine. Those with too much phlegm were phlegmatic. Those with too much yellow bile were choleric, and those with too much black bile were melancholic. The idea of human personality based on humors contributed to the character comedies of Menander and, later, Plautus.
Through the neo-classical revival in Europe, the humor theory dominated medical practice, and the theory of humoral types made periodic appearances in drama. Such typically "eighteenth-century" practices as bleeding a sick person or applying hot cups to a person were, in fact, based on the humor theory of surpluses of fluids (blood and bile in those cases). Ben Jonson wrote humor plays, where types were based on their humoral complexion.
Additionally, because people believed that there were finite amounts of humors in the body, there were folk/medical beliefs that the loss of fluids was a form of death.
History and the connection with temperament theory
Although modern medical science has thoroughly discredited humorism, this "wrong-headed theory dominated medical thinking... until at least the middle of the 20th century, and in certain ways continues to influence modern-day diagnosis and therapy."
The concept of four humors may have origins in ancient Egypt or Mesopotamia, but it was not systemized until ancient Greek thinkers around 400 BC who directly linked it with the popular theory of the four elements earth, fire, water and air (Empedocles). Paired qualities were associated with each humour and its season. The word humour derives from the Greek χυμός, chymos (literally juice or sap, metaphorically flavor).
The four humours, their corresponding elements, seasons, sites of formation, and resulting temperaments alongside their modern equivalents are: Hippocrates is the one credited with applying this idea to medicine. Humoralism, or the doctrine of the four temperaments, as a medical theory retained its popularity for centuries largely through the influence of the writings of Galen (131-201 AD) and was decisively displaced only in 1858 by Rudolf Virchow's newly published theories of cellular pathology. While Galen thought that humours were formed in the body, rather than ingested, he believed that different foods had varying potential to be acted upon by the body to produce different humours. Warm foods, for example, tended to produce yellow bile, while cold foods tended to produce phlegm. Seasons of the year, periods of life, geographic regions and occupations also influenced the nature of the humours formed.
The imbalance of humours, or dyscrasia, was thought to be the direct cause of all diseases. Health was associated with a balance of humours, or eucrasia. The qualities of the humours, in turn, influenced the nature of the diseases they caused. Yellow bile caused warm diseases and phlegm caused cold diseases.
In On the Temperaments, Galen further emphasized the importance of the qualities. An ideal temperament involved a balanced mixture of the four qualities. Galen identified four temperaments in which one of the qualities, warm, cold, moist or dry, predominated and four more in which a combination of two, warm and moist, warm and dry, cold and dry or cold and moist, dominated. These last four, named for the humours with which they were associated—that is, sanguine, choleric, melancholic and phlegmatic, eventually became better known than the others. While the term temperament came to refer just to psychological dispositions, Galen used it to refer to bodily dispositions, which determined a person's susceptibility to particular diseases as well as behavioral and emotional inclinations.
In Islamic medicine, Avicenna (980-1037) extended the theory of temperaments in The Canon of Medicine to encompass "emotional aspects, mental capacity, moral attitudes, self-awareness, movements and dreams." He summarized his version of the four humours and temperaments in a table as follows:
Rhazes (865-925) was the first physician to refute the theory of four humours in his Doubts about Galen. He carried out an experiment which would upset this system by inserting a liquid with a different temperature into the body resulting in an increase or decrease of bodily heat, which resembled the temperature of that particular fluid. Rhazes noted that a warm drink would heat up the body to a degree much higher than its own natural temperature, thus the drink would trigger a response from the body, rather than transferring only its own warmth or coldness to it. Avenzoar (1091-1161) carried out an experimental dissection and autopsy to prove that the skin disease scabies was caused by a parasite, a discovery which upset the theory of humorism. The removal of the parasite from the patient's body did not involve purging, bleeding, or any other traditional treatments associated with the four humours. Ibn al-Nafis (1213-1288) then discredited the theory of four humours after his discovery of the pulmonary circulation and coronary circulation.
Methods of treatment like blood letting, emetics and purges were aimed at expelling a harmful surplus of a humour. They remained part of mainstream Western medicine until the 17th century when William Harvey investigated the circulatory system. Other methods used herbs and foods associated with a particular humour to counter symptoms of disease, for instance: people who had a fever and were sweating were considered hot and wet and therefore given substances associated with cold and dry.
There are still remnants of the theory of the four humours in the current medical language. For example, we refer to humoral immunity or humoral regulation to mean substances like hormones and antibodies that are circulated throughout the body, or use the term blood dyscrasia to refer to any blood disease or abnormality. The associated food classification survives in adjectives that are still used for food, as when we call some spices "hot" and some wine "dry". When the chilli pepper was first introduced to Europe in the sixteenth century, dieticians disputed whether it was hot or cold.
The humours can be found in Elizabethan works, such as in Taming of the Shrew, in which the character Petruchio pretends to be irritable and angry to show Katherina what it is like being around a disagreeable person. He yells at the servants for them serving mutton, a "choleric" food, to two people who are already choleric.
Foods in Elizabethan times were believed all to have an affinity with one of these four humours. A person suffering from a sickness in which they were coughing up phlegm were believed to be too phlegmatic and might have been served wine (a choleric drink and the direct opposite humour to phlegmatic) to balance it out.
The theory was a modest advance over the previous views on human health that tried to explain disease in terms of evil spirits. Since then, practitioners have started to look for natural causes of disease and to provide natural treatments.
The Unani school of Indian medicine, still apparently practiced in India, is very similar to Galenic medicine in its emphasis on the four humours and in treatments based on controlling intake, general environment, and the use of purging as a way of relieving humoral imbalances.
humorism in German: Humoralpathologie
humorism in Urdu: اخلاط (طب)
humorism in French: Humeur#L'humeur en médecine
humorism in Finnish: Humoraalioppi
humorism in Dutch: Humores