However, medieval doctors had little concept of germs as the medium of disease and the cause of illness. While the body was known to degenerate with age, medieval doctors believed that a healthy body required a state of harmony or balance. An unhealthy body represented an imbalance, usually identified through a change or sign on the outside of the body, either on the skin or from an excreted fluid, such as urine. Thus the body becomes the symbolic text which a doctor needed to interpret in order first to diagnosis and then to cure.
Lacking any concept of viruses or bacteria as causes of illness, medieval doctors were left to reason that certain behaviors led to illness. There were three types of possible illnesses: those caused by the body's natural degeneration, those to which the body was predisposed, and those caused by immoderate living.
The connection between morality and illness is not a medieval creation, but part of the heritage of Greco-Roman medicine. Galen unified two competing theories, the Empiricists and the Dogmatists into one philosophy which became the foundation of medieval medicine. The Empiricists believed in experience as the greatest teacher of medical learning. The Dogmatists relied on a learned tradition and propounded a notion of a microcosm and macrocosm. The microcosm consisted of the four bodily humours: blood, phlegm, black bile, and yellow bile. Each of the four humours reflected the elements of the macrocosm: air, water, earth, and fire, respectively. The humours also had temperature and moisture properties. Blood was hot and wet, phlegm was cold and wet, black bile was cold and dry, and yellow bile was hot and dry. According to this theory, when a person became sick, one of the four humours was out of balance. To balance the humours, one needed to take a prescription, usually made from some combination of plants or animals. Doctors categorized all plants and animals by their temperature and moisture.
Galen believed that authoritative learning was important but must not be accepted blindly; "rather, [medical authorities] are authorities in as far as they are proved right" through clinical experience. Essentially, Galen saw medicine as a cumulative process in which one studied medical authorities and appended or altered the authoritative corpus through clinical experience. Galen's emphasis on immoderation as a cause of illness appealed especially to early Christians.
A third misconception about medieval medicine concerns ascribing the belief to medieval people that all illness was connected to moral failings. In fact, some illnesses were believed to occur naturally or as a result of old age.
The clearest literary example of both the influence of medicine on literature and the connection between morality and illness appears in our own adjectives: sanguine, choleric, phlegmatic, and melancholy. At one time, these adjectives referred both to the emotional and moral state of the individual as well as to his or her physical constitution. Each ... ailment corresponds to an emotional state--an emotional state that could lend itself to sin. The assumptions which underlie this poem are that the phlegmatic is prone to the sin of idleness, the sanguine is prone to the sins of lust and overindulgence, the choleric is prone to the sins of covetousness, and the melancholic is prone to the sins of deceit and envy.
https://web.archive.org/web/20050306190053/http://www.the-orb.net:80/non_spec/missteps/ch4.html
http://blogs.bl.uk/digitisedmanuscripts/2015/04/ointments-and-potions.html
Apothecary, Barber, Pharmacist, Physician, Surgeon
https://www.youtube.com/playlist?list=PL745-VcJ1xdWwpYGTyu2lr3PeL5OR1yy1 .
