Galen (129–216 CE)

 

Galen was a Greek physician, surgeon, and philosopher who worked during the Roman Empire. He is considered one of the most important figures in the history of medicine. Building on the work of Hippocrates, Galen helped shape medical knowledge for over 1,000 years.

Key Contributions

Anatomy and Physiology

• Galen studied the structure and function of the body by dissecting animals, especially monkeys and pigs, because human dissection was generally not permitted.
• His work greatly improved understanding of anatomy and physiology at the time.
• However, because he relied on animal dissections, some of his ideas about the human body were later shown to be incorrect.

Medical Writing

• Galen wrote hundreds of medical books and essays covering anatomy, disease, diagnosis, treatment, surgery, and pharmacology.
• His writings became the main medical textbooks in Europe and the Middle East for many centuries.
• Doctors and medical students studied his work until scientific discoveries in the 16th and 17th centuries challenged many of his theories.

Observation and Experience

• Galen believed that physicians should carefully observe patients, record symptoms, and learn through practical experience.
• He combined scientific observation with philosophical thought, believing that medicine should be grounded in reason as well as experience.

Theory of the Four Humors

Like Hippocrates, Galen believed that good health depended on maintaining a balance between the four humors:

• 🩸 Blood – associated with being cheerful and energetic.
• 💛 Yellow bile – associated with anger and determination.
• 🖤 Black bile – associated with sadness and seriousness.
• 🤍 Phlegm – associated with calmness and slow reactions.

According to Galen, illness occurred when these humors became unbalanced. Treatments such as dietary changes, exercise, herbal medicines, or bloodletting were used to restore balance.

Legacy

Galen's influence lasted from the 2nd century CE until the 17th century. His work shaped medicine throughout the Roman Empire, the Islamic Golden Age, medieval Europe, and the Renaissance. Although many of his anatomical theories were eventually corrected through human dissection and scientific research, his emphasis on careful observation, medical ethics, and systematic study helped lay the foundations of modern medicine.

Easy Read Summary

• Galen was a Greek doctor who lived from 129–216 CE.
• He worked in the Roman Empire.
• He built on the ideas of Hippocrates.
• He studied anatomy by dissecting animals.
• He wrote many important medical books.
• He believed doctors should learn through observation and experience.
• He supported the Four Humors Theory, believing good health depended on keeping the body's humors in balance.
• His ideas influenced medicine for over 1,000 years, until newer scientific discoveries replaced many of his theories.

Key Fact: Although some of Galen's ideas were later proven incorrect, his commitment to careful observation, learning, and recording medical knowledge made him one of the most influential physicians in history.