Who was the most important ancient doctor after Hippocrates?
After Hippocrates, there was another important doctor in antiquity, but he became far less famous. Galen from Pergamon, born in 129 and died in 199 AD, is a rather unknown personality despite his great works.
But what were his works? The most famous works by Galen of Pergamon include, for example , Simplicia , a treatise on simple remedies , a medical pathology that went down in medical history as humoral pathology, and of course his life’s work, an examination of the books of the Corpus hippocraticum .
Even great thinkers start small…
He was able to make his first medical observations and learn healing methods as a gladiator doctor. He later perfected his knowledge on long journeys. Around 161 he settled in Rome and became famous there for his medical skills, his studies on animals and his public lectures.
He dissected animals…
Goats, pigs and monkeys were used to dissect – this allowed him to show how different muscles are controlled by different areas of the spine. He recognized the roles of the kidneys and bladder and identified seven pairs of cranial nerves. He also showed that the brain controls the voice.
Galen discovered that the arteries carry blood, not air (as had been thought for 400 years). He also described the heart valves  and noted the difference in structure between arteries and veins, but he did not realize that blood circulates in a circulatory system.
He tried his hand at being a philosopher
Galen wrote mathematical and philosophical writings. For example, following the ideas of Aristotle, in his treatise  On the functions of the human body parts  , he held the view that nothing in nature is superfluous and that everything has a specific meaning. Galen’s fundamental contribution to philosophical thought was the idea that God’s purposes could be known through the study of nature.
All in all a great man
Galen wrote about 500 treatises on medicine, philosophy and ethics, many of which survive in translation. The anatomical findings were his most important scientific achievements and milestones in medicine.