Technology & Medicine › Ancient world › Classical medicine (Greece, India, China)
Galen
AD 129 – c. 216· Person· Medicine & surgery
Well documentedSolid records, physical evidence or scientific consensus.
Greek physician in Rome whose experiments and vast writings made him medicine's highest authority for about 1,400 years.
See it on the Technology & Medicine map →How it works
Born in Pergamon (now Bergama, Turkey), Galen treated gladiators, then became physician to Emperor Marcus Aurelius. Human dissection was taboo in Rome, so he dissected apes and pigs. He showed that arteries carry blood, not air, and that cutting a nerve in the neck silenced a squealing pig, proving the brain controls the voice. He championed Hippocrates' four humours and wrote hundreds of treatises, but applied some animal anatomy wrongly to humans.
Why it mattered
His blend of experiment and theory became the textbook of Byzantine, Islamic and European medicine; challenging his errors drove the anatomy and circulation breakthroughs of the 1500s–1600s.
Legacy and how we know
Some 20,000 printed pages of his Greek works survive, plus texts known only in Arabic or Latin translation; he wrote much about his own career.
Still unknown or debated
How faithfully he reported his own cures is uncertain; he was a self-promoter. Many works burned in a Rome fire in 192; one lost essay resurfaced in 2005.
Connections (5)
▸Hippocrates was systematised by GalenWell documented
The connection
Six centuries after Hippocrates, Galen made himself the champion and interpreter of the Hippocratic writings. He wrote long commentaries on them, developed their theory of four humours (blood, phlegm, yellow bile, black bile), and fused it with anatomy and his own experiments into one system that dominated medicine for 1,400 years.
When and how
Pergamon and Rome, about AD 150–200, working from Hippocratic texts collected and edited at Alexandria.
How we know
Galen's surviving commentaries on Hippocratic works such as Epidemics and Aphorisms, and his treatise On the Doctrines of Hippocrates and Plato.
Debates and open questions
Which 'Hippocratic' texts Hippocrates actually wrote is unknown; Galen shaped the image of Hippocrates we inherit, perhaps partly in his own image.
▸Galen was corrected by Vesalius's De humani corporis fabricaWell documented
The connection
For about 1,300 years, Galen's writings defined anatomy in Europe and the Islamic world. Vesalius at first followed Galen but, dissecting human bodies himself, found errors that came from Galen's reliance on apes and other animals. His Fabrica openly corrected Galen, shifting authority from ancient texts to direct observation.
When and how
Galen worked in Pergamon and Rome in the 100s AD; Vesalius dissected at Padua from 1537 and published the Fabrica in Basel in 1543.
How we know
The Fabrica names Galen's errors explicitly, and Galen's own texts show he relied mostly on animal dissection, since human dissection was not practiced in Rome.
Debates and open questions
Scholars debate how sharp the break was: Vesalius kept much of Galen's physiology and only cautiously doubted Galen's invisible pores in the heart's wall.
▸Galen was synthesised in Ibn Sina's Canon of MedicineWell documented
The connection
Galen's works, translated into Arabic in Baghdad, were the backbone of Islamic medicine. Ibn Sina arranged Galen's physiology, humours, pulse lore and drugs into one orderly framework, squared where possible with Aristotle's philosophy, and added later knowledge. Through the Canon, Galen's medicine reached Europe in a tidier, more teachable form.
When and how
Persia: begun in Gorgan about 1012 and completed in Hamadan around 1025, using the Arabic translations of Hunayn ibn Ishaq's circle.
How we know
The Canon follows Galen's doctrines throughout and names him often; it openly tries to reconcile him with Aristotle, for example on the heart's role.
Debates and open questions
How far Ibn Sina reshaped Galen versus simply condensing him is still discussed by historians.
▸Galen was overturned by Harvey's discovery of blood circulationWell documented
The connection
Galen taught that the liver turned food into blood, which flowed outward and was consumed by the body, some seeping through tiny pores in the heart's wall. Harvey's measurements showed the heart pumps far too much blood for that to work, so blood must circulate. His proof overturned Galen's model of the blood after about 1,400 years.
When and how
Galen wrote in Rome around AD 160–200; Harvey, royal physician to James I and then Charles I, published De Motu Cordis in Frankfurt in 1628.
How we know
Harvey's book argues directly against Galen's model, and his measurements and tourniquet experiments could be repeated by anyone; most physicians accepted circulation within about 30 years.
Debates and open questions
Harvey kept other ancient ideas, such as the blood's vital spirit; historians debate whether he saw himself as overthrowing Galen or correcting him.
▸Galen was corrected on the heart by Ibn al-Nafis and the lung circulationWell documented
The connection
Galen taught that blood seeped from the heart's right side to its left through invisible pores in the dividing wall (septum). Ibn al-Nafis, commenting on anatomy in 1242, said the septum is solid and impermeable, so blood must go from the right ventricle through the lungs to reach the left: the pulmonary circulation.
When and how
Cairo, about 1242, in his Commentary on the Anatomy of Ibn Sina's Canon.
How we know
His text explicitly rejects Galen's pores, stating the septum has no visible or invisible passage; manuscripts of it survive.
Debates and open questions
He wrote that religious law and compassion kept him from dissection, so whether his insight came from reasoning, animal dissection or unrecorded observation is debated.