Medicine as a system of ideas
Medieval learned medicine was not a collection of unrelated cures. It was a framework in which anatomy, physiology, disease, drugs, diet and even the heavens were connected by a small number of principles. Understanding these principles explains why a physician looked at a patient’s age, the season and the date before choosing a remedy. This article looks at that framework as a whole, rather than at individual treatments or at the humors in detail, which are covered elsewhere on this site.
The sources of the system
The structure drew on three main sources. The first was the Hippocratic tradition, which stressed balance and the influence of environment. The second was Galen, a physician of the Roman Empire in the second century, who combined Hippocratic ideas with Aristotle’s philosophy and large-scale anatomical and physiological theory. The third was the Arabic tradition, in which writers developed and organized this inheritance, and made it easier to teach. Ibn Sina’s Canon of Medicine became a standard textbook, and works by Rhazes and others also circulated.
This material reached the Latin West through translation, mostly from the eleventh to the thirteenth century. The tradition of translation associated with the House of Wisdom and with scholars in Spain and Italy was one of the main routes. Once in Latin, the texts were taught in the universities, where the scholastic method, a technique of posing questions, quoting authorities and resolving contradictions, was applied to medicine as it was to theology.
Balance and complexion
The central idea was balance. Health was a state in which the body’s qualities, hot, cold, moist and dry, were in suitable proportion. Each individual had a natural balance, called complexion, which was healthy for that person. Disease occurred when the balance shifted too far, and treatment aimed to bring it back toward the individual’s own norm and not toward some universal standard.
This made medicine highly individual in theory. The same illness could call for different treatments in a young man and an old woman, in summer and in winter, in a hot country and a cold one. Individual factors such as age, sex and occupation all belonged in the assessment, and this is one reason that physicians offered personalized regimens.
Elements and humors
The qualities were tied to the four elements: earth, air, fire and water. The humors in the body were thought to correspond to these elements and qualities, a connection described in the material on the four elements. From this followed the broader picture of the human being as a small version of the universe, or microcosm, with the body mirroring the cosmos. The theory of humors was one specific part of this picture, but not the whole.
Natural functions, spirits and organs
Physiology in the Galenic tradition described several faculties, or powers, with main organs associated with each. The liver was linked to nutrition and the production of blood, the heart to the vital spirit that gave heat and life, and the brain to the animal spirit that carried sensation and movement. These ideas were not purely abstract. They guided how physicians understood digestion, fever, fainting and nervous disorders, and gave a reason for treating particular organs.
Food passed through a series of “digestions” or “concoctions” in the stomach, liver and tissues. Illness was often explained by failures in these processes, such as unconcocted matter building up. The notion of waste products being expelled by sweat, urine or bowels explained why evacuations were so commonly recommended.
The stars and medicine
Astrology was integrated into learned medicine, not treated as a separate subject. The planets and signs of the zodiac were believed to influence the body and the weather. The idea of the “zodiac man,” an image showing which sign ruled which part of the body, is a familiar example, and calendars guided decisions about bloodletting and the gathering of herbs. Many physicians held that illness could turn on critical days influenced by the moon, which fit into the broader study of medieval astrology.
The use of astrology was not universal or uncritical. Some writers doubted how far the stars could be known to affect disease, and practical physicians often gave astrology only a minor role. But in major crises, it was prominent. In 1348, the medical faculty at Paris is reported to have produced a report on the Black Death that attributed it to a planetary conjunction and corrupted air, a reasonable application of its own theory at the time.
The role of authority and reason
Medieval medicine placed great weight on authority. Teaching was based on reading and commenting on texts, and a physician justified a treatment by citing Galen or Ibn Sina as well as experience. This could make the system conservative, but it was not simply blind. Commentators noticed contradictions, debated them and sometimes proposed new solutions. Surgeons and some physicians stressed the value of experience, and anatomical dissection began to be performed at some universities in the late Middle Ages, mainly to illustrate the texts rather than to challenge them.
Strengths and weaknesses
The system was coherent, flexible and comprehensive. It gave physicians a way to explain illness, predict its course and justify a treatment plan, and it encouraged attention to diet, environment and the individual patient. Its weaknesses were that it was hard to test, offered no route to understanding infectious disease, and often supported treatments such as bloodletting that did not help.
It is also important to remember that this was the theory of the learned. Most people lived in a world of home remedies and religious healing, and the practitioners who treated them rarely thought in these terms. The system mattered because it set the standard for what counted as expert knowledge, and it lasted well beyond the Middle Ages.