Psychology and medicine, finding their beginnings in Greek culture, have come a long way; and since their speculative foundations, their influence has become larger, more pertinent, and more accurate than ever before, with the invention of prosthetics in the field of medicine and cognitive studies in psychology, for example. It seems as though anything is possible, as though nothing cannot be achieved. One may wonder, then, from where psychology came, from whom modern medicine developed. Small questions, like why, when someone is in a bad mood, we say they are in bad humor; or why, when someone is angry, we say they are hot-blooded, or short-tempered, never fail to come up regarding the origins of either discipline. A glance through history, to the invention of psychology, can show us the foundations of both psychology and medicine—the ancient system of humorism.
The theory of the four humors is derived from the Pre-Socratic philosopher Empedocles (c. 490-430 BC) who posited the existence of the four basic elements that constituted all of reality: air, fire, earth, and water. Everything in the world, he explained, was a synthesis of all four, each contributing their unique characteristics and properties to create everyday objects. For this reason, early theory in medicine was based on philosophical theory, so the two subjects were closely intermingled, the cause of many a medical error in ancient times. The man whom we ought to credit for the beginnings of modern medicine is the Greek physician Hippocrates (c. 460-370 BC), who is most renown for the Hippocratic Oath, which is still used today. Despite the countless contributions he has made to medicine, there is difficulty when it comes to pinpointing which works he actually wrote and which works were written by either his student Polybus or perhaps even rival doctors of his. Some of his works, furthermore, seem to diverge in content, contradicting earlier theories. Central to Hippocrates’ method was a holistic approach to the body. “Hippocrates the Asclepiad says that the nature even of the body can only be understood as a whole,” remarked Plato . Each part of the body was to be examined against every other part, so as to treat everything as one. He wrote of a popular principle at the time: “Certain sophists and physicians say that it is not possible for any one [sic] to know medicine who does not know what man is.” Such importance placed upon the human body and its composition made the humoral theory possible, as well as the secularization of medicine itself. Apollo and Asclepius, the Gods of medicine, were thought to be the causes of disease up until Hippocrates, who, diagnosing epilepsy—once thought the work of the Gods—said it “appears… to be nowise more divine nor more sacred than any other disease, but has a natural cause from which it originates like other affectations.”
The natural cause of which Hippocrates spoke was the humors. From the Latin word umor, meaning fluid, the humors were four fluids within the body, each aligning with one of the four elements of Empedocles. Hippocrates identified blood with fire, phlegm with water, black bile with earth, and yellow bile air. During the Scientific Revolution, the 16th-century physician William Harvey performed studies on the circulatory system, when he would eventually disprove Hippocrates and Galen. Acknowledging the two physicians and Aristotle (he supported the humoral theory), he wrote in his book regarding animal generation, “And thus they [the Ancients] arrived at their four humors, of which the pituita [phlegm] is held to be cold and moist; the black bile cold and dry; the yellow bile hot and dry; and the blood hot and moist.” According to Hippocrates, one could tell whether the upcoming season would be one of sickness or health by analyzing the weather; if there were extreme conditions, like extreme coldness during winter or heavy rains during spring, then more diseases were to be expected, whereas normal conditions foretold of health and prosperity. Cold seasons exacerbated the cold humors, phlegm and black bile; while warm seasons exacerbated the warm humors, yellow bile and blood. Alchemist Philippus Aureolus Theophrastus Bombastus von Hohenheim, or Paracelsus (1493-1541), was a notorious physician during his time, often burning the works of Galen in public to disrespect him and his theories. Instead of the four humors, Paracelsus preferred a more alchemical approach, diagnosing based on saltiness, sweetness, bitterness, and sourness, adding a fifth property, life. In addition, he gave these elements their own properties, such as combustibility, solidness, fluidity, and vaporousness. The human body has a balance to it, what Hippocrates judged as a body’s krasis (κρασις), or mixture. A healthy body has a good mixture, eucrasia (ευκρασια), meaning it has an even amount of all four humors. Pausanias, a doctor in The Symposium, explains that,
The course of the seasons is also full of both these principles; and when, as I was saying, the elements of hot and cold, moist and dry, attain the harmonious love of one another and blend in temperance and harmony, they bring to men,… health and plenty, and do them no harm.
While one should strive for an ideal balance, eucrasia, one should stay as far away as possible from dyscrasia (δυσκρασια), or bad mixture, for if it is extreme, it can result in death. Too much phlegm (mucus), warns Hippocrates, can clog the throat, choking off airflow, resulting in asphyxiation, for instance. Another Renaissance physician, shortly after Paracelsus, named Santorio Santorio (1561-1636), calculated that between the perfect balance of eucrasia and the imperfect balance of dyscrasia lie 80,000 unique diseases stemming from different combinations of humors. Determined to prove Hippocrates and Galen right, Santorio carried out extensive experiments, measuring the body’s temperature before and after diagnosis with a thermoscope, then measuring it daily thereafter, comparing each new temperature to the healthy one.
“Those diseases which medicines do not cure, iron cures; those which iron cannot cure, fire cures; and those which fire cannot cure, are to be reckoned wholly incurable,” stated Hippocrates confidently . Should some poor soul suffer from dyscrasia, there were several cures with which he could proceed, and there was a cure for each type of imbalance. Hippocrates invested his faith in incisions, stating that iron, by which he means knife, is the next step up from remedies; if surgery does not work, he says one should proceed to cauterize; but if fire does not work, then one is out of luck. Other proposed cures were sweating and vomiting, which would either excrete or purge any excess humors. Of course, then there was bloodletting, the deadly, inaccurate method of making a cut in the skin and cleansing the blood. So popular was bloodletting that by the 1500’s, “[t]reatment was still based on the Hippocratic theory of humors, and bloodletting was a panacea.” Virtually any disease could be cured by bloodletting—that is, until William Harvey. Besides these cleansing methods, there was an easier, more efficient way of handling humoral diseases, one which did not require knives or fire: using opposites to counteract. If there was too much blood, a doctor could counteract it with black bile, opposing the hotness and moistness of the former with the coldness and dryness of the latter; similarly, too much yellow bile could be countered with phlegm, and vice versa. Hippocrates was also famous for prescribing his patients varying diets that would in the same way counter the excess humor, usually advising the replacement of wheat with bread, of water with wine.
This raises the question, though: Why does humorism matter, why is it relevant at all, considering it is outdated and completely incorrect, and why should we be interested? As I said at the beginning, humorism was the foundation for psychology; specifically the foundation for the psychology of personality, a much-studied and much-debated area of research today. Roman physician Galen (c. 130-200) was arguably the first person to attempt a formal study of personality. A studied physician of Hippocratic writings, a learned student of Stoic logic, Galen was an empiricist at heart, emphasizing experience over speculation, what he called demonstrative knowledge (επιστημη αποδεικτικη). Neither Hippocrates nor Galen studied the interior of the human body, as the dissection of humans was taboo; thus, their findings were purely theoretical, which is rather ironic for Galen, who did cut open animals, just not humans. Galen identified two types of passions: irascible passions, those which are negative, and concupiscible, those which are positive . He observed four temperaments arising from the four humors. (Temperament, interestingly, translates to mixture!) In fact, “Before the invention of the clinical thermometer and even for some time afterwards, bodily ‘temperature’ was only a synonym for ‘temperament.’” His theory of the four temperaments is so influential that their adjectives have carried over today: too much blood creates a sanguine character who is cheerful; too much phlegm a phlegmatic who is calm; too much yellow bile a choleric who is angry; and too much black bile a melancholic who gloomy; and for the latter two, one can say bilious. Hippocrates noticed these characteristics in his time and attested, commenting, “Those who are mad from phlegm are quiet, and do not cry nor make a sound; but those from vile are vociferous, malignant, and will not be quiet, but are always doing something improper.”
One may dissent again: Why is this relevant? for it is outdated. Although Galen’s theory of the four temperaments is largely out of use , it has spawned interest in following psychologists of personality. The infamous Myers-Briggs Type Indicator, or MBTI (1943), can be seen as a derivative. It utilizes different traits to arrive at a certain personality. Those who wish to know their personality have to decide if they are introvert or extrovert, if they intuit or sense, think or feel, and perceive or judge. Another option, the Big Five, or Big Three (1949), identifies people based on their levels of openness, conscientiousness, extraversion, agreeableness, and neuroticism. Big Three limits the scales to neuroticism, extraversion, and openness. Lastly, the direct descendant is psychologist Hans J. Eysenck (1916-1997), whose method of deducing personality was influenced entirely by Galen. Eysenck created a dichotomy between extraversion and introversion, neuroticism and psychoticism, recognizing several character traits reminiscent of Galen.
 Plato, Phaedrus, 270c
 Hippocrates, On Ancient Medicine, p. 13b*
 Hippocrates, On the Sacred Disease, p. 326a
 Harvey, Anatomical Exercises on the Generation of Animals, p. 435b*
 Plato, The Symposium, 188a
 Hippocrates, Aphorisms, §7, 87
 Durant, The Story of Civilization, Vol. 5, p. 532
 This is a very superficial description; for a more detailed one, read Aquinas’ Summa Theologica, 1.81.2,ad.1
 Boorstin, The Discoverers, p. 341
 Hippocrates, On the Sacred Disease, 337a
 Read Florence Littauer’s Personality Plus for a modern perspective
For further reading:
Greek Thought: A Guide to Classical Knowledge by Jacques Brunschwig (2000)
The Oxford Companion to Classical Civilization by Simon Hornblower (1998)
Anatomical Experiments on the Generation of Animals by William Harvey
An Intellectual History of Psychology by Daniel N. Robinson (1995)
The Encyclopedia of Philosophy Vol. 3 by Paul Edwards (1967)
The Encyclopedia of Philosophy Vol. 4 by Paul Edwards (1967)
The Encyclopedia of Philosophy Vol. 6 by Paul Edwards (1967)
The Story of Civilization Vol. 2 by Will Durant (1966)
The Story of Civilization Vol. 3 by Will Durant (1972)
The Story of Civilization Vol. 5 by Will Durant (1953)
The Psychology Book by Wade E. Pickren (2014)
The Story of Psychology by Morton Hunt (1993)
The Discoverers by Daniel J. Boorstin (1983)
On the Sacred Disease by Hippocrates
On Ancient Medicine by Hippocrates
On the Natural Faculties by Galen
Extra reading for fun: Personality Plus by Florence Littauer (1992)
*Pages referenced to Great Books of the Western World, Vol. 9, 26, by Mortimer J. Adler (1990), respectively