The timeline of medicine begins much earlier than medieval times—in fact, medicine's history extends back to the prehistoric era—but it was during the medieval age that certain medical advances were made which would prove to be particularly important in the future. Lessons learned during medieval age clearly brought about the success of the early organizations of Christian hospitals and clinics in Asia and Africa.

The Medieval System of Medicine

The most well-respected physician during the medieval era was Galen of Pergamum, a Greek who had lived in the second century B.C. During the time in which he lived, his work had added a great deal of important information to the store of medical knowledge—including study on inflammation, infectious diseases, and pharmacology.

At this time, qualifying as a Doctor of Medicine involved ten years' worth of study, and because of this there were relatively few doctors. Women were did not train as doctors, but many medical practitioners actually were women, until the increasing regulation of the profession began to exclude people who had not trained from practicing.

The Medieval Theory: Four Humors

During the medieval era, the prevailing medical theory was the theory of humours, which was pioneered by Hippocrates and further developed by Galen of Pergamum. The theory of humours ended up being very long-lived—it was not until the nineteenth century that it began to fall out of use.

According to the theory, the body was made up of four principal humours—fluids—called yellow bile, black bile, blood, and phlegm. All diseases were caused by imbalances in the body's proportion of the various humours. For example, too much phlegm in the body would cause lung diseases, and would cause the lungs to cough up the excess phlegm in an attempt to restore the balance between the four humours. Each of the four humours was also associated with particular organs, climate types, elements, and even personality types.

Treating various diseases often involved the application of herbs, which were supposed to help restore the balance between the humors. Using herbs lent itself to the Christian “Doctrine of Signatures,” which stated that God had provided a world in which the cure for every ailment existed, and that each cure had on it some sort of sign which proclaimed its purpose. For example, Lungwort, which was used to treat tuberculosis, had an appearance similar to that of diseased lungs.

The High Medieval Era

It wasn't until the end of the medieval era that some of those important advances were made. During this era, for example, Theodoric Borgognoni pioneered the introduction of one of the most important concepts in modern medicine: the use of antiseptic practices. Other physicians contributed immensely to the store of knowledge, including Realdo Colombo and Michael Servetus, both of whom discovered important knowledge about the circulatory systenm.