In 1799 George Washington woke with a severe throat infection, and over the next 10 hours his doctors drained more than 124 ounces of his blood. He died shortly after. This episode explains how deliberate bleeding stayed the standard of care for over 2,000 years. The Ebers Papyrus records scarification in Egypt, possibly inspired by hippos whose red skin secretion looked like self bleeding. Hippocrates linked purging to menstruation, and Galen, who believed blood did not circulate and could pool as plethora, built a detailed map of which vein to cut for which organ.

Physicians handed the cutting to barber surgeons, who used lancets, arteriotomy, and the spring loaded brass scarificator. In 1628 William Harvey proved blood circulates, yet bleeding continued for two more centuries. In 1824 a French sergeant stabbed in a duel lost about 13 pints to his doctors plus dozens of leeches, and his physician credited the bleeding with saving him. In the 1830s Pierre Charles Alexandre Louis used his numerical method to show bleeding failed in pneumonia, while François Broussais kept prescribing up to 50 leeches at a time.

• France imported about 40 million leeches a year in the 1830s, and England about 6 million from France
• In 1623 Jacques Ferrand recommended bleeding to cure a broken heart
• Shock from heavy blood loss made feverish patients go pale and still, which looked like a cure
• The Human Relations Area Files show bloodletting arose independently in 60 cultures
• Therapeutic phlebotomy is still used for hemochromatosis, an iron overload disorder