Five Quarts_ A Personal and Natural History of Blood - Bill Hayes [9]
The circulatory system as conceived by Galen
Truth be told, I find scientific blunders as fascinating as the great discoveries. It’s the main reason I enjoy reading archaic medical texts, a trusty form of time travel I undertake at libraries. Being in the position of knowing more than Galen did is satisfying, I will not deny. It’s also sobering. Two decades from now I’m sure I’ll look back and shake my head, amazed at the things Steve and I once did in the name of cutting-edge science. But there’s something else. Looking back at Galen looking forward, I am touched by his efforts to treat deadly illnesses, to alleviate suffering, however futile. Finally, he is most impressive not in having come up with so many answers but in taking on so many big questions, such as, What is the essence of life? What makes us human? Galen believed the ingredients were in the bloodstream, where a trio of incorporeal “spirits” flowed. (By contrast to the groupings of four used at that time to describe the inner and outer workings of the universe—the humors, the qualities, the elements—the spirits came in threes, reflecting the tripartite division of the soul theorized by Plato.) The first two ran in the dark, purplish blood of the veins: Natural Spirits, brewed in the liver, providing the body’s mass; and Animal Spirits, fired in the brain, producing movement. Completing the trinity were Vital Spirits, the essence that separated human beings from animals. In its fleet passage through the heart, the scarlet arterial blood was imbued with this zest, which disseminated warmth and verve throughout the body. In Galen’s reckoning, the spirits did not intermingle; the veins and arteries were separate streams.
As scientific bunglings go, Galen was in good company. No less a genius than Leonardo da Vinci (1452–1519) made some spectacular ones in his notebooks of anatomical drawings. Leonardo, who dissected cadavers and sketched directly from them, set out with the express goal of being faithful only to the evidence of his eyes. Unlike Galen, he held a lifelong aversion to verbiage and believed that drawing was the only uncontestable means of expression. That being said, Leonardo still could not escape Galen’s lingering influence. This groundbreaking artist who rendered with astonishing accuracy the chambers of the heart, for example, and the fetus in utero, nevertheless added fictitious plumbing to the human body—canals, ducts, and veins—to accommodate humoral theory. Likewise, he drew the spleen cartoonishly large, proportional to its inflated role in secreting the illusory black bile. Another fallacy perpetuated by Galen and then by Leonardo was the kiveris vein, which resolved the biological puzzle of why pregnant women stopped menstruating. The answer: Menstrual blood was converted into mother’s milk, of course, and this “milk vein” conveyed it from the uterus to the breasts. Uniquely male anatomy was fictionalized, too. In cross sections of the penis, Leonardo added a phantom vein for “vital impulse,” the life-giving oomph ejected alongside sperm. Of all Leonardo’s fabrications, the cleverest, I think, was his explanation for crying. A slender vessel carried tears from the heart, the organ of the emotions, up to the eyes. (One last phantom vessel of note is the vena amoris, the “love vein,” first described by the ancient Egyptians and absorbed into Christian ceremony in the fourth century. The vena amoris, it was believed, carried blood straight from the fourth finger of the left hand to the heart, which accounts for the enduring custom of wearing one’s wedding band on this finger.)
I take it that, in the past, it was easier to believe in the unseen, the unproven. To feel certain that universal forces were reflected in the human body. Modern medical technologies all but dash these notions. Still, I share Galen’s and Leonardo’s conviction that real answers can be found within, even though they don’t show up on MRIs, CAT