Galen

Galen of Pergamon, commonly known simply as Galen, was a prominent Greek physician, surgeon, and philosopher of the Roman Empire who lived circa 129 to circa 216 CE. He produced an enormous corpus of medical and philosophical works that shaped Western medical theory for more than a millennium. His writings drew on earlier Greek medical thought, especially Hippocrates, and on his own clinical experience and anatomical studies.

Born in Pergamon (modern Bergama, Turkey), Galen studied in various centers such as Smyrna, Alexandria, and other Greek-speaking cities. He practiced medicine in Pergamon and later relocated to Rome, where he served as a physician to physicians and possibly to the imperial household and gymnastic institutions associated with gladiators. His clinical work emphasized careful observation, logical argument, and the systematization of medical knowledge.

Galen expanded the theory of the four humors—blood, phlegm, yellow bile, and black bile—as the basis of health and disease, and he developed detailed theories of anatomy, physiology, and pharmacology. Much of his anatomical knowledge came from animal dissection, which sometimes led to errors in human anatomy but also advanced systematic study. His comprehensive treatises covered anatomy, physiology, pathology, pharmacology, and medical ethics, and he authored numerous practical manuals used by physicians for centuries.

Galen’s influence endured through the medieval Islamic world and later in Europe, where his texts were studied, annotated, and expanded. While later scientific advances challenged many of his conclusions, his work established a durable framework for medical inquiry and practice that markedly shaped the history of medicine.