Most medieval ideas about medicine were based on those of the ancient work, namely the works of Greek physicians Galen (AD 129-216) and Hippocrates (460BC-370BC). Their ideas set out a theory of the human body relating to the four elements (earth, air, fire and water) and to four bodily humours (blood, phlegm, yellow bile and black bile). It was believed that health could be maintained or restored by balancing the humours, and by regulating air, diet, exercise, sleep, evacuation and emotion. Doctors also often advised risky invasive procedures like bloodletting.
Medical knowledge derived from antique theory was largely confined to monasteries and the highly educated. For ordinary people, especially those outside towns, it would have been difficult to access professional practitioners. Those in need of medical assistance might instead turn to local people who had medical knowledge, derived from folk traditions and practical experience.
The Stars and planets
Medieval astrologers believed that the movements of the stars influenced numerous things on earth, from the weather and the growth of crops to the personalities of new born babies and the inner workings of the human body. Doctors often carried around special almanacs (or calendars) containing illustrated star charts, allowing them to check the positions of the stars before making a diagnosis. Many of these almanacs included illustrations, helping to explain complicated ideas to patients. The picture below shows a 'zodiac man' from one of these almanacs from 1399. The diagram was intended to explain how the astrological formations (or star signs) rule over each part of the body. The man's pointing finger serves as a warning against the powerful forces of the stars.
Ancient studies of astrology were translated from Arabic to Latin in the 12th and 13th centuries and soon became part of everyday medical practice in Europe. By the end of the 1500s, physicians across Europe were required by law to calculate the position of the moon before carrying out complicated medical procedures, such as surgery or bleeding.
A diagram known as the 'Zodiac man' superimposed the appropriate star sign onto body parts; in a manuscript owned by the Barber Surgeons of York, this diagram faces a circular wheel marked with astrological data and equipped with a moving pointer (known as a volvelle) so that the physician could align the data according to the position of the sun and moon.
One of the main ways in which a physician would diagnose illness was by examining stools, blood and especially urine: physicians were often depicted in images holding a flask of urine up to the light.
Some medical treatises contain illustrations showing urine in different hues, thus aiding the physician in his diagnosis.
Wounds, ruptures and lesions
Another area of medical concern was how to treat wounds, ruptures and lesions, in which the surgeon specialised. One illustrated treatise demonstrates a procedure for a skull fracture, which is accompanied by a narrative of Christ's life; this juxtaposition may hint at the need for divine assistance for both surgeon and patient. Although it is impossible to determine the success rate of such interventions, the survival of medieval skulls with bone that has knitted together after the treatment of an injury demonstrates that even traumatic head wounds were not always fatal.
John Arderne (died c.1377), an English surgeon, composed medical works on topics such as the treatment of eyes and the cure of anal fistula, both of which circulated widely. Arderne's works are fascinating in a number of respects, not least of which is the fact that illustrations are integral to them.
Medicine and the Church
In medieval Europe, medicine generally operated within the context of the Christian church. Hospitals which cared for the elderly and the ill were often run by religious orders, which could maintain infirmaries for their own members and operate hospitals for others. Where professional medicine could not help, the faithful often turned to saints, and visited saints' shrines in the hope of miraculous cures. The windows of the Trinity Chapel in Canterbury Cathedral, completed c.1220, show pilgrims suffering from illness, injury and even insanity flocking to Becket's shrine; in some scenes, physicians with urine flasks turn away in despair, unable to equal the healing power of the saint.
The sick might also have turned to the occult: the dividing line between magic and medicine is not always obvious in medieval sources, and many medical practitioners used occult knowledge to heal the sick either by natural means (using, for example, herbs to treat or prevent illness or ward off danger) or using demonic magic, which attempted to use diabolical forces to intervene with human affairs.