The concept of "humors" (chemical systems regulating human behaviour) became more prominent from the writing of medical theorist Alcmaeon of Croton (C. 540-500 BC). His list of humours was longer and included fundamental elements described by Empedocles, such as water, air, earth, etc. Some authors suggest that the concept of "humours" may have origins in Ancient Egyptian medicine or Mesopotamia, though it was not systemized until ancient Greek thinkers. The word humor is a translation of Greek ,chymos (literally juice or sap, metaphorically flavor). Ancient Indian Ayurveda medicine had developed a theory of three so-called doshas (do?as), which they linked with the five elements (pañca-bh?ta) earth, water, fire, air and space.
Hippocrates is the person usually credited with applying this idea to medicine. In contrast to Alcmaeon, Hippocrates suggested that humours are the vital bodily fluids, such as blood, yellow bile, phlegm and "black bile" (he probably referred to blood composites in patients with bleeding internal organs). Alcmaeon and Hippocrates posited that an extreme excess or deficiency of any of the humours bodily fluid in a person can be a sign of illness. Hippocrates and then Galen suggested that a moderate imbalance in the mixture of these fluids produces temperament (behavioural) type. One of the treatises attributed to Hippocrates, On the Nature of Man, describes the theory as follows:
The Human body contains blood, phlegm, yellow bile and black bile. These are the things that make up its constitution and cause its pains and health. Health is primarily that state in which these constituent substances are in the correct proportion to each other, both in strength and quantity, and are well mixed. Pain occurs when one of the substances presents either a deficiency or an excess, or is separated in the body and not mixed with others.
Although the theory of the four humors does appear in some Hippocratic texts, some Hippocratic writers only accepted the existence of two humors, while some even refrained from discussing the humoral theory at all. 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 (129-201 AD). Hippocrates' theory of four humours was linked with the popular theory of the four elements (earth, fire, water and air) proposed by Empedocles, but this link wasn't proposed by Hippocrates or Galen who referred primarily to bodily fluids. While Galen thought that humors were formed in the body, rather than ingested, he believed that different foods had varying potential to be act upon the body to produce different humors. 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 humors formed.
The imbalance of humors, or dyscrasia, was thought to be the direct cause of all diseases. Health was associated with a balance of humors, or eucrasia. The qualities of the humors, 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 humors with which they were associated -- 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.
Disease could also be the result of the "corruption" of one or more of the humors, which could be caused by environmental circumstances, dietary changes, or many other factors. These deficits were thought to be caused by vapors inhaled or absorbed by the body. Greeks and Romans, and the later Muslim and 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 of the four fluids, then said patient's personality and or physical health could be negatively affected.
Even though humorism theory had several models that used 2, 3 and 5 components, the most famous model consists of the four humors described by Hippocrates and then developed further by Galen. The four humors of Hippocratic medicine are black bile (Greek: ? ?, melaina chole), yellow bile (Greek: ?, xanthe chole), phlegm (Greek: , phlegma), and blood (Greek: ?, haima). Each corresponds to one of the traditional four temperaments. Based on Hippocratic medicine, it was believed that the four humors were to be in balanced proportions with regard to amount and strength of each humor for a body to be healthy. The proper blending and balance of the four humors was known as 'eukrasia'. Imbalance and separation of humors leads to diseases.
Galen recalls the correspondence between humors and seasons in his On the Doctrines of Hippocrates and Plato, and says that, "As for ages and the seasons, the child (?) corresponds to spring, the young man () to summer, the mature man (µ?) to autumn, and the old man () to winter". Galen also believed that the characteristics of the soul follow the mixtures of the body but he does not apply this idea to the hippocratic humours. He believed that the phlegm did not influence character. Here is what he says in his On Hippocrates' The Nature of Man: "Sharpness and intelligence ( ?) are caused by yellow bile in the soul, perseverance and consistency (? ?) by the melancholic humour, and simplicity and naivety ( ) by blood. But the nature of phlegm has no effect on the character of the soul ( ?µ? ? µ )." He further said that blood is a mixture of four elements: water, air, fire, earth.
These terms only partly correspond to the modern medical terminology, in which there is no distinction between black and yellow bile and phlegm has a very different meaning. It was believed that these were the basic substances from which all liquids in the body were made. Robin Fåhræus (1921), a Swedish physician who devised the erythrocyte sedimentation rate, suggested that the four humours were based upon the observation of blood clotting in a transparent container. When blood is drawn in a glass container and left undisturbed for about an hour, four different layers can be seen. A dark clot forms at the bottom (the "black bile"). Above the clot is a layer of red blood cells (the "blood"). Above this is a whitish layer of white blood cells (the "phlegm"). The top layer is clear yellow serum (the "yellow bile").
Many Greek texts were written during the golden age of the theory of the four humors in Greek medicine after Galen. One of those texts was an anonymous treatise called On the Constitution of the Universe and of Man, published in the mid-nineteenth century by J.L. Ideler. In this text the author establishes the relationship between elements of the universe (air, water, earth, fire) and elements of the man (blood, yellow bile, black bile, phlegm). He said that:
Excess of yellow bile was thought to produce aggression, and reciprocally excess anger to cause liver derangement and imbalances in the humors.
The word "melancholy" derives from Greek ? ? (melaina kholé) meaning 'black bile'. Depression was attributed to excess or unnatural black bile secreted by the spleen. Cancer was also attributed to an excess of black bile concentrated in a specific area.
Phlegm was thought to be associated with reserved behavior, as preserved in the word "phlegmatic". The phlegm of humorism is far from the same thing as phlegm as it is defined today. The French physiologist and Nobel laureate Charles Richet, when describing humorism's "phlegm or pituitary secretion" in 1910, asked rhetorically, "this strange liquid, which is the cause of tumours, of chlorosis, of rheumatism, and cacochymia--where is it? Who will ever see it? Who has ever seen it? What can we say of this fanciful classification of humours into four groups, of which two are absolutely imaginary?"
Humors are produced via digestion and are the final products of hepatic digestion. Digestion is a continuous process taking place in every human being and it can be divided into four sequential stages. The gastric digestion stage, the hepatic digestion stage, the vascular digestion stage, and the tissue digestion stage. Each stage digests food until it becomes suitable for use by the body. In gastric digestion, food is made into chylous which is suitable for liver to absorb and carry on digestion. Chylous is changed into 'chymous' in the hepatic digestion stage. Chymous is composed of the four humors: blood, phlegm, yellow bile, and black bile. These four humors then circulate in the vessels. And in the last stage of digestion, tissue digestion, food becomes similar to the organ tissue that it is destined for.
If anything goes wrong leading up to the formation of humors, the humors will not be in good condition. From the kind of food that goes into the body to the proper organ functioning is necessary in the production of good humor. The stomach and liver have to function normally in order for proper digestion. If there are any abnormalities in gastric digestion the liver, blood vessels and tissues can not be provided with the raw chylous and that can cause abnormal humor and blood composition. A healthy functioning liver is not even capable of converting abnormal chylous into normal chylous and then normal humors.
Humors are the end product of gastric digestion but they are not the end product of the digestion cycle so an abnormal humor produced by hepatic digestion will lead to affect other organs that are working towards the digestion of the food in the digestion cycle.
Empedocles's theory suggested that there are four elements: earth, fire, water, and air; with earth producing the natural systems. Since this theory was influential for centuries, later scholars paired qualities associated with each humour as described by Hippocrates-Galen with seasons and "basic elements" as described by Empedocles.
The following table shows the four humors with their corresponding elements, seasons, sites of formation, and resulting temperaments:
|Blood||spring||infancy||air||liver||warm and moist||sanguine|
|Yellow bile||summer||youth||fire||gallbladder||warm and dry||choleric|
|Black bile||autumn||adulthood||earth||spleen||cold and dry||melancholic|
|Phlegm||winter||old age||water||brain/lungs||cold and moist||phlegmatic|
Medieval medical tradition in the "Golden Age of Islam" adopted the theory of humorism from Greco-Roman medicine, notably via the Persian polymath Avicenna's The Canon of Medicine (1025). Avicenna summarized the four humors and temperaments as follows:
|Morbid states||Inflammations become febrile||Fevers related to serious humor, rheumatism||Lassitude||Loss of vigour|
|Functional power||Deficient energy||Deficient digestive power||Difficult digestion|
|Subjective sensations||Bitter taste, excessive thirst, burning at cardia||Lack of desire for fluids||Mucoid salivation, sleepiness||Insomnia, wakefulness|
|Physical signs||High pulse rate, lassitude||Flaccid joints||Diarrhea, swollen eyelids, rough skin, acquired habit||rough skin, acquired habit|
|Foods and medicines||Calefacients harmful, infrigidants beneficial||Infrigidants harmful, calefacients beneficial||Moist articles harmful||Dry regimen harmful, humectants beneficial|
|Relation to weather||Worse in summer||Worse in winter||Bad in autumn|
The Unani school of medicine, practiced in Perso-Arabic countries, India, and Pakistan, is based on Galenic and Avicennian medicine in its emphasis on the four humors as a fundamental part of the methodologic paradigm.
The humoralist system of medicine was highly individualistic, for all patients were said to have their own unique humoral composition. From Hippocrates onward, the humoral theory was adopted by Greek, Roman and Islamic physicians, and dominated the view of the human body among European physicians until at least 1543 when it was first seriously challenged by Andreas Vesalius. Vesalius mostly criticized Galen's theories of human anatomy and not the chemical hypothesis of behavioural regulation (temperament). However, some believe that theory of humours was cast into the underside of science in 1628 by the findings of William Harvey (also criticising mostly anatomy theory of Galen) and by Rudolf Virchow's theories of cellular pathology in 1858.
Typically "eighteenth-century" practices such as bleeding a sick person or applying hot cups to a person were, in fact, based on the humoral theory of imbalances of fluids (blood and bile in those cases). Ben Jonson wrote humor plays, where types were based on their humoral complexion. Methods of treatment like bloodletting, emetics and purges were aimed at expelling a surfeit of a humor. Other methods used herbs and foods associated with a particular humor 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. Paracelsus further developed the idea that beneficial medical substances could be found in herbs, minerals and various alchemical combinations thereof. These beliefs were the foundation of mainstream Western medicine well into the 17th century. Specific minerals or herbs were used to treat ailments simple to complex, from an uncomplicated upper respiratory infection to the plague. For example, chamomile was used to decrease heat, and lower excessive bile humor. Arsenic was used in a poultice bag to 'draw out' the excess humor(s) that led to symptoms of the plague. Apophlegmatisms, in pre-modern medicine, were medications chewed in order to draw away phlegm and humours.
Although advances in cellular pathology and chemistry criticized humoralism by the seventeenth century, the theory had dominated Western medical thinking for more than 2,000 years. Only in some instances did the theory of humoralism wane into obscurity. One such instance occurred in the sixth and seventh centuries in the Byzantine Empire when traditional secular Greek culture gave way to Christian influences. Though the use of humoralist medicine continued during this time, its influence was diminished in favor of religion. The revival of Greek humoralism, owing in part to changing social and economic factors, did not begin until the early ninth century. Use of the practice in modern times is pseudoscience.
Modern medicine refers to humoral immunity or humoral regulation when describing substances such as hormones and antibodies but this is not a remnant of the humor theory. It is merely a literal use of humoral , i.e., pertaining to bodily fluids (such as blood and lymph).
The concept of humorism was not "definitively demolished" until 1858. There were no studies performed to prove or disprove the impact of dysfunction in known bodily organs producing named fluids (humors) on temperament traits simply because the list of temperament traits was not defined up until the end of 20th century.
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.
The humors 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 serving mutton, a "choleric" food, to two people who are already choleric.
Foods in Elizabethan times were all believed to have an affinity with one of these four humors. A person showing signs of phlegmatism might have been served wine (a choleric drink and the direct opposite humor to phlegmatic) to balance this.