As bizarre as this seems, it was perfectly logical according to the prevailing principles of Western medicine.
The treatment was observed in the ancient cultures of Egypt and Mesopotamia, and advanced in the Roman Empire through the writings of Greek physician Galen. He supported Hippocrates’ theory that illness was caused by an imbalance of the body’s four humours – black bile, yellow bile, blood and phlegm. Blood was the dominant humour, and relieving any excess supply was essential to the healing process.
Bloodletting charts – such as 15th-century ‘Zodiac Man’ – indicated the best place for draining blood according to the patient’s astrological sign and specific complaint. Scientific inquiries of the 1600s presented challenges to the humoural theory – not least the discovery that the blood circulated the body, rather than being produced by the liver – but had little impact on medical practice. Bleeding, it was argued, was nevertheless beneficial in reducing inflammation.
Methods did vary over time – many practitioners simply opened a vein (in many cases there was little need for a doctor; the local ‘barber surgeon’ was happy to oblige). In the 1800s it became popular to use scarificators (small mechanisms making numerous incisions in the skin) or apply blood-sucking leeches.
Only in the later Victorian era did bloodletting as a universal cure begin to be discredited, and it fell from fashion in the face of new medical discoveries.