Five Quarts_ A Personal and Natural History of Blood - Bill Hayes [5]
Neither of Galen’s most distinguished predecessors, Aristotle (384–322 B.C.) and the Greek physician Hippocrates (460–375 B.C.), had ever dissected a human body. And those who had performed dissections noted that the corpse’s arteries were empty (because, as a modern pathologist would explain, blood drains back into the veins once the heart stops). This led the great thinkers to the false conclusion that the arteries contained only an air-like substance. Hence artery, derived from a Greek word meaning “air duct.” Galen, with virtual human vivisections at his disposal, was able to correct this error. Clearly, the arteries were filled with blood. Further, he accurately traced the course of blood from the right side of the heart to the left via the pulmonary artery and lungs. The most crucial discovery, however—that the arteries, veins, and heart work together as a circulatory system—would not be made until the 1600s.
Despite his new insights, the foundation of Galen’s medical philosophy did not change. He embraced the ancient Hippocratic theory that a person’s state of health was determined by four fluids, or humors—blood, phlegm, yellow bile, and black bile—which had to be in perfect balance within the body for good health to prevail. When one or more of these fluids was overabundant or insufficient, the body’s inner scales tipped and disease resulted. The humor called black bile deserves special mention because, as modern medical historians point out, it is a fictitious substance, though Galen firmly believed it existed. Conceptually, there had to be four humors—not three, not five—because the body was seen as a microcosm of the universe, which was organized in patterns of four: the basic elements (earth, air, fire, water) and their cosmological correlates (the Earth, sky, sun, sea); the four seasons; and what were known as the Aristotelian “qualities” (cold, damp, hot, and dry). All of these aspects were interrelated, sometimes overlapping, in an elaborate system that Galen would later codify in his medical books. Phlegm, for example, was cold, damp, watery, and wintry, while blood was hot, damp, air-, and spring-like. That the microcosm mirrored the macrocosm was a defining part of Galen’s diagnoses. After patching up a gladiator who’d lost a large amount of blood, for instance, he would likely have prescribed a huge increase in the man’s dietary intake. In the doctor’s view, the liver—the body’s hot, damp organ—was “the principal instrument of sanguification”; it converted digested food into blood. The patient, by gorging himself, would restore his humoral balance. Were another gladiator unable to fight because of, say, a high fever, Galen would have diagnosed “plethora,” an excess of humors in his body. As treatment, Galen would have turned to copious bloodletting.
With only a slight shift in thinking, I can understand Galen’s rationale. Since physical appearance was one of the few diagnostic tools available to him, it’s not wholly absurd that Galen would’ve concluded from a flushed, fevered face that the patient was suffering from superfluous blood. Or, similarly, that a sallow complexion meant that the gallbladder—the hot, dry organ—was producing too much yellow bile. To have explained to Galen that things floating in the blood actually caused disease would’ve made as much sense to him in his day as saying his fax needed paper. In second-century medicine it wasn’t the quality of blood that was at issue, but the quantity. One could have too much of a good thing.
Doctors in Galen’s time had other methods for cutting off the body’s production of fresh blood: getting the patient to stop eating for several days or inducing vomiting (after all, who doesn’t look a bit