galen and medicine -- 8/30/23

Today's selection -- from A Little History of Science by William Bynum. Born in Anatolia in 129 CE, the Greek physician Galen and his writings dominated European medicine for well over a thousand years:

“Galen (129-210 CE) was very clever and was not afraid to say so. He scribbled constantly, and his writings are full of his own opinions and accomplishments. More of his words survive than those of any other author from ancient times, which proves that people valued Galen's works very highly. There are twenty fat volumes that you can read, and he actually wrote many more. So we know more about Galen than we do about most other ancient thinkers. It doesn't hurt that Galen also adored writing about himself.

“Galen was born in Pergamum, now part of Turkey but then on the fringes of the Roman Empire. His father was a prosperous architect who was devoted to his gifted son, providing him with a sound education (in Greek) which included philosophy and mathematics. Who knows what might have happened had his father not had a powerful dream, telling him that his son ought to become a doctor? Galen changed his studies to medicine. After his father's death left him well-off, he spent several years travelling and learning, spending time at the famous library and museum in Alexandria in Egypt.

“Back in Pergamum, Galen became a doctor to the gladiators -- the men chosen to entertain well-to-do citizens by fighting each other, or by facing lions and other beasts in the arena. Taking care of them was an important job, since the poor men needed to be patched up between the shows so they could keep on fighting. By his own account, Galen was extremely successful. He would have had dramatic experience in the surgical treatment of wounds. He also acquired a considerable reputation among the rich and, around AD 160, he took himself to Rome, the capital of the Roman Empire. He began writing on anatomy (the study of the bodily structures of humans and animals) and physiology (the study of what those structures do). He also went on a military campaign with the Emperor Marcus Aurelius. The emperor was the author of a famous series of Meditations and the two men discussed philosophy during the long campaign. Marcus Aurelius appreciated Galen, and Galen profited from the emperor's support. A steady stream of important patients were sent his way whom, if Galen's reports are to be believed, he always cured if they could be.

“Galen's medical hero was Hippocrates, even though he had been dead for more than 500 years. Galen saw himself as completing and extending the master's legacy, and, in many ways, this is exactly what he did. He produced commentaries on many of the Hippocratic works, and assumed that the works that agreed most closely with his own views were by Hippocrates himself. His comments on Hippocrates are still valuable, not least because Galen was an expert linguist with a good eye for the changing meanings of words. Most importantly, he put the Hippocratic doctrine of the humours in the form that was used for more than a thousand years. Imagine being that influential!

“The idea of the balance and imbalance of the humours was central to Galen's medical practice. Like Hippocrates, he believed that the four humours -- blood, yellow bile, black bile and phlegm -- were, in special ways, hot or cold, and moist or dry. To treat a malady, you chose an 'opposite' remedy, but also one of the same intensity. So diseases that were hot and moist in the third degree, for example, would be treated with a remedy that was cold and dry in the third degree. For example, if the patient had a runny nose and felt chilled, drying, warming medicines and food would be used. By rebalancing the humours, you could restore a healthy 'neutral' state. This was all very logical and simple, but in reality things were more complicated. Doctors still needed to know a great deal about their patients, and administer their remedies with care. Galen was always quick to point out when other doctors got it wrong (which was often) so that everyone knew his diagnoses and therapies were better. He was a shrewd doctor, much in demand, who paid great attention to the mental as well as physical aspects of health and disease. He once diagnosed a case of 'lovesickness', where a young lady became weak and nervous whenever a handsome male dancer was performing in town. 

16th-century illustration of the four humors: Flegmat (phlegm), Sanguin (blood), Coleric (yellow bile) and Melanc (black bile)

“Galen came up with the practice of feeling his patient's pulse -- something that doctors still do. He wrote a treatise on how the pulse -- slow or fast, strong or faint, regular or irregular -- could be useful in diagnosing disease, even though he had no idea about the circulation of the blood. 

“Galen was more interested in anatomy than the Hippocratics. He opened up the bodies of dead animals and examined human skeletons wherever he could. Dissecting human bodies was frowned upon in ancient societies, so Galen could not do that, although we think that a few earlier doctors might have been allowed to examine the bodies of condemned criminals while they were still alive. Galen learned about human anatomy from dissections of animals, like pigs and monkeys, and by lucky chances -- discovery of a decaying dead body, or bad injuries that showed structure of skin, muscle and bone. Scientists still use animals in their research, but they must be careful to be clear about where they got their information. Galen often forgot to mention where he had got his facts from, so it could be confusing. 

“Anatomy was, for Galen, an important subject in its own right, but it was also fundamental for understanding what the organs of the body actually do. One of his most influential treatises was called On the Uses of the Parts, which looked at the structures of the 'parts’ or organs, and what role they played in the working of the whole human body. Galen assumed, as you would do, that each part does do something, otherwise it wouldn't be there. (I doubt if he ever saw the human appendix. That tiny part of our digestive organs probably long, long ago helped us to digest plants, but it doesn't have a function any more.) 

“At the centre of all bodily function was a substance the Greeks called pneuma. 'Pneuma' is not easily translated into English: we'll use 'spirit' but it also has the idea of 'air'; it has given rise to various medical terms in our own times, such as 'pneumonia'. For Galen, the body contained three kinds of pneuma, and understanding what they each did was central to understanding how the body functions. The most basic kind of pneuma was associated with the liver, and was concerned with nutrition. The liver, Galen believed, was able to draw material from the stomach after it had been eaten and digested, turn it into blood and then infuse it with 'natural' spirit. This blood from the liver then coursed through the veins throughout the body, to nourish the muscles and other organs. 

“Some of this blood passed from the liver through a large vein, the vena cava, into the heart where it was further refined with another spirit, the 'vital' one. The heart and lungs worked together in this process, some of the blood passing through the pulmonary artery (going from the right side of the heart) into the lungs. There it nourished the lungs and also mixed with the air we breathe in through the lungs. Meanwhile, some of the blood in the heart assed from right to left through the middle portion of the heart the septum). This blood was bright red because, Galen thought, it had the vital spirit infused within it. (Galen recognised that blood in the arteries is a different colour from blood in the veins.) From the left side of the heart, blood went out via the aorta, the large artery taking blood from the left chamber, or ventricle, of the heart, in order to warm the body. Despite his appreciation of the importance of blood in the life of an individual, Galen had no sense that the blood circulates, as William Harvey was to discover almost 1,500 years later. 

“In Galen's scheme, some of the blood from the heart also went to the brain, where it was mixed with the third kind of pneuma, the 'animal' spirit. This was the most refined kind of spirit. It gave the brain its own special functions as well as flowing out through the nerves, enabling us to move using our muscles and to experience the external world using our senses.

“Galen's three-part system of spirits, each associated with the important organs (liver, heart, brain), was accepted for more than a thousand years. It's worth remembering that Galen used this system primarily to explain how our bodies work when we are healthy. When he tended sick patients, he continued to rely on the system of humours devised by the Hippocratics.

“Galen also wrote about most other aspects of medicine, such as drugs and their properties, the diseases of the special organs like the lungs, hygiene, or how to preserve health, and the relationship between our minds and our bodies. His thinking was very sophisticated. In fact he believed that a doctor should be both a philosopher and an investigator, a thinker and an experimenter. He argued that medicine should, above all, be a rational science, and he paid a lot of attention to the best ways to gain good, reliable, knowledge. Later doctors, who also saw themselves as learned men of science, liked Galen's mix of practical advice (based on his vast experience) and broad thinking. No single Western doctor in all history has exerted such an influence for so long.

“There are several reasons for Galen's long shadow. First, he had a very high opinion of Aristotle, so that the two were often spoken about together. Like Aristotle, Galen was a deep thinker and an energetic investigator of the world. Both believed this world had been designed, and praised the Designer. Galen was not a Christian but he believed in a single God, and it was easy for early Christian commentators to include him in the Christian fold. His confidence meant that he had an answer for everything. Like most people who write many books over a long period, he was not always consistent but he was always definite in his opinions. He was commonly referred to later as 'the divine Galen', a label of which he would have been proud.”



William Bynum


A Little History of Science


Yale University Press


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