Galen of Pergamon

Galen combined dissection, controlled experiment and philosophical system-building into a body of medical writing so complete that it functioned as the final word in Europe and the Islamic world until the Renaissance. He proved the arteries carry blood, mapped the nervous system by severing spinal cords in pigs, and made medicine an evidence-claiming discipline.

• Demonstrated by ligature experiments that arteries carry blood, not air, overturning centuries of doctrine
• Mapped cranial nerves and showed the brain, not the heart, controls voice and movement
• Wrote roughly 300 works — perhaps 10% of all surviving Greek literature is by Galen
• Served as physician to Marcus Aurelius, Commodus and Septimius Severus

Galenic method — observe, dissect, experiment, then reason — is the ancestor of clinical research, and his insistence that a physician be also a philosopher underlies modern medical ethics teaching. Because his errors were canonised, overturning them created modern science: Vesalius corrected his anatomy in 1543 and Harvey his circulation in 1628, and those two acts of dissent define the scientific method taught in every laboratory today. Pharmacy still calls compounded preparations 'galenicals'.

Galen never married and left no children. His posterity was textual: he trained no dynasty but produced a corpus that generations of physicians treated as an inheritance.