I touched briefly on Galen in my article “Skinning your Own Apes,” because the title of that piece was inspired by an odd detail I noted in one of his works. But the man himself deserves greater length. The theories of medicine and anatomy he advanced influenced the foundations of medical practice for centuries.
Galen (129 CE- c. 216) was a Greek philosopher and physician who left a variety of treatises covering internal medicine, surgery and anatomy. Although it was Hippocrates who began the theory of the four humors that governed the moods of man and were related to four liquids in the human body, it was Galen who promoted controlling these imbalances as a pathway to health, and took up Hippocrates’ ideas about bloodletting to correct the humors, an idea that persisted for more than a thousand years.
In an era when human dissections were illegal, Galen’s use of animal dissections analogous to humans is worthy of praise. However, this did allow for certain misconceptions about things like, oh, say, the placement of the liver, and flaws in his anatomical charts for women which were based on pigs. Still, it made for a good base of knowledge for most purposes.
He also performed a variety of daring surgeries, including cataract surgery, and the use of ligature to control bleeding. While medieval physicians embraced most of Galen with perhaps too much enthusiasm, they did not subscribe to all of his techniques. Galen may have written as many as 600 treatises, of which only about three million words survive, thanks to their transmission and translation by Byzantine and Muslim scholars.
Galen was the acknowledged master by the university-educated physicians, so influential that any actual human whose anatomy defied Galen’s drawings was said to be the anomaly: it was Galen who was the authority, not the evidence plainly seen by the surgeon on the spot. Strange, to think that your own body would be taken for an aberration if found to be in opposition to the text.
During my period of study, the writing of medical texts always included a large number of shout-outs to those who went before, even if the author was planning to refute or ignore them. In the works of medieval medical authors like Guy de Chauliac, each description of a procedure begins with noting how the same procedure was handled by Avicenna and Galen (sometimes others as well), citing the work where the master had described his work, then elaborating, but rarely daring to defy his example.
Nowadays, especially in the medical realm, we prize the new. We assume that the latest science, the newest technique, the test or medicine just approved by the FDA is clearly the best. We seem to have swung to the opposite pole, always looking ahead for the answers, just as the doctors of the Middle Ages were always looking behind. Our technology and techniques affords a much more clear understanding of physiology, though in many areas of practice and daily medical care, it still requires courage to suggest the authority may be mistaken.
Flawed as he was, Galen stood as a medical pioneer, not only for his own era, but for centuries to come.