Humor?

Ask what the cause of many diseases is (germs, bacteria, viruses). Only recently have we found that small organisms cause disease. Before this, physicians and others were unaware of these organisms. Still, they had to try to explain the cause of sickness. They did this by pointing to what were called “humors.” Physicians in the 1700s and 1800s believed that disease and sickness was caused by an imbalance in what were called “humors” of the body (blood, phlegm, yellow bile, black bile). It was crucial, some believed, that the body remained balanced; so it was important, for instance, that we not become too cold or hot, too wet or dry. If we did, our humors would be out of balance, and we could get sick. Colds, for example, were a result of too much phlegm, and throwing up a result of too much bile. If you were sick, essentially, your humors were out of balance. To restore this balance, many physicians would practice what was called “bloodletting.” They would cause a patient to bleed so that the “bad blood” would be removed from the body and proper balance of the humors was reinstated. Bloodletting, in fact, could be used for fever, inflammations, coughing, asthma, epilepsy, headaches, and after suffering a bruise, a fall, or a blow.

It's interesting to me, too, that humor refers both to these fluids and to a quality that causes amusement.