humorism humorism humorism, the humoral theory, or humoralism, was a system of medicine detailing a supposed makeup and workings of the human body, adopted by ancient greek and roman physicians and philosophers. this article is about humors in ancient and medieval medicine. for the related theory of temperament, see four temperaments. for humors in ayurvedic medicine, see ayurveda. for the use of humor in writing or public speaking, see humorist. 16th-century illustration of the four humors: flegmat (phlegm), sanguin (blood), coleric (yellow bile) and melanc (black bile). part of a series onscience overview history literature philosophy scientific method scientist branches formal natural physical life social applied engineering medical interdisciplinary society communication education funding pseudoscience policy sociology outline science portal category humorism began to fall out of favor in the 17th century and it was definitely disproved in the 1850s with the advent of germ theory, which was able to show that many diseases previously thought to be humoral were in fact caused by microbes. origin 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 humors was longer and included fundamental elements described by empedocles, such as water, air, earth, fire, etc.. the concept of "humors" 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 χυμός, chymos (literally juice or sap, metaphorically flavor). ancient indian ayurveda medicine had developed a theory of three doshas (doṣas), which they linked with the five elements (pañca-bhūta): earth, water, fire, air, and space. hippocrates is usually credited with applying this idea to medicine. in contrast to alcmaeon, hippocrates suggested that humors are the vital bodily fluids: blood, phlegm, yellow bile, and black bile. alcmaeon and hippocrates posited that an extreme excess or deficiency of any of the humors (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 behavioral patterns. 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. the body depends heavily on the four humors because their balanced combination helps to keep people in good health. having the right amount of humor is essential for health. the pathophysiology of disease is consequently brought on by humor excesses and/or deficiencies. the existence of fundamental biochemical substances and structural components in the body remains a compellingly shared point with hippocratic beliefs, despite the fact that current science has moved away from those four hippocratic humors. although the theory of the four humors does appear in some hippocratic texts, other hippocratic writers accepted the existence of only two humors, while some 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). the four essential elements—humors—that make up the human body, according to hippocrates, are in harmony with one another and act as a catalyst for preserving health. hippocrates' theory of four humors was linked with the popular theory of the four elements (earth, fire, water, and air) proposed by empedocles, but this link was not 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 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. as such, certain seasons and geographic areas were understood to cause imbalances in the humors, leading to varying types of disease across time and place. for example, cities exposed to hot winds were seen as having higher rates of digestive problems as a result of excess phlegm running down from the head, while cities exposed to cold winds were associated with diseases of the lungs, acute diseases, and "hardness of the bowels," as well as ophthalmies (issues of the eyes), and nosebleeds. cities to the west, meanwhile, were believed to produce weak, unhealthy, pale people that were subject to all manners of disease. in the treatise, airs, waters, places, a hippocratic physician is described arriving to an unnamed city where they test various factors of nature including the wind, water, and soil to predict the direct influence on the diseases specific to the city based on the season and the individual. a fundamental idea of hippocratic medicine was the endeavor to pinpoint the origins of illnesses in both the physiology of the human body and the influence of potentially hazardous environmental variables like air, water, and nutrition, and every humor has a distinct composition and is secreted by a different organ. aristotle's concept of eucrasia—a state resembling equilibrium—and its relationship to the right balance of the four humors allow for the maintenance of human health, offering a more mathematical approach to medicine. the four humors as depicted in an 18th-century woodcut: phlegmatic, choleric, sanguine and melancholic. 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 proportionally 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 humors, then said patient's personality and/or physical health could be negatively affected. therefore, the goal of treatment was to rid the body of some of the excess humor through techniques like purging, bloodletting, catharsis, diuresis, and others. bloodletting was already a prominent medical procedure by the first century, but venesection took on even more significance once galen of pergamum declared blood to be the most prevalent humor. the volume of blood extracted ranged from a few drops to several litres over the course of several days, depending on the patient's condition and the doctor's practice. four humors 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 developed further by galen. the four humors of hippocratic medicine are black bile (greek: μέλαινα χολή, melaina chole), yellow bile (greek: ξανθη χολή, xanthe chole), phlegm (greek: φλέγμα, phlegma), and blood (greek: αἷμα, haima). each corresponds to one of the traditional four temperaments. based on hippocratic medicine, it was believed that for a body to be healthy, the four humors should be balanced in amount and strength. the proper blending and balance of the four humors was known as "eukrasia". humorism theory was improved by galen, who incorporated his understanding of the humors into his interpretation of the human body. he believed the interactions of the humors within the body were the key to investigating the physical nature and function of the organ systems. galen combined his interpretation of the humors with his collection of ideas concerning nature from past philosophers in order to find conclusions about how the body works. for example, galen maintained the idea of the presence of the platonic tripartite soul, which consisted of “thumos (spiritedness), epithumos (directed spiritedness, i.e., desire), and sophia (wisdom).” through this, galen found a connection between these three parts of the soul and the three major organs that were recognized at the time: the brain, the heart, and the liver. this idea of connecting vital parts of the soul to vital parts of the body was derived from aristotle's sense of explaining physical observations, and galen utilized it to build his view of the human body. the organs (named organa) had specific functions (called chreiai) that contributed to the maintenance of the human body, and the expression of these functions is shown in characteristic activities (called energeiai) of a person. while the correspondence of parts of the body to the soul was an influential concept, galen decided that the interaction of the four humors with natural bodily mechanisms were responsible for human development and this connection inspired his understanding of the nature of the components of the body. 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 (παῖς) corresponds to spring, the young man (νεανίσκος) to summer, the mature man (παρακµάζων) to autumn, and the old man (γέρων) to winter". he also related a correspondence between humors and seasons based on the properties of both. blood, as a humor, was considered hot and wet. this gave it a correspondence to spring. yellow bile was considered hot and dry, which related it to summer. black bile was considered cold and dry, and thus related to autumn. phlegm, cold and wet, was related to winter. galen also believed that the characteristics of the soul follow the mixtures of the body, but he did not apply this idea to the hippocratic humors. he believed that phlegm did not influence character. in his on hippocrates' the nature of man, galen stated: "sharpness and intelligence (ὀξὺ καὶ συνετόν) are caused by yellow bile in the soul, perseverance and consistency (ἑδραῖον καὶ βέβαιον) by the melancholic humor, and simplicity and naivety (ἁπλοῦν καὶ ἠλιθιώτερον) by blood. but the nature of phlegm has no effect on the character of the soul (τοῦ δὲ φλέγµατος ἡ φύσις εἰς µὲν ἠθοποιῗαν ἄχρηστος)." he further said that blood is a mixture of the four elements: water, air, fire, and earth. these terms only partly correspond to 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 the humors 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 humors 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