BY ANDREA MONGLER
ILLUSTRATION FROM NLM/SCIENCE SOURCE/SCIENCE PHOTO LIBRARY
For thousands of years, bloodletting was a widely accepted and commonly used treatment for a variety of illnesses. The practice stemmed from the belief that disease was caused by an imbalance of the four bodily fluids, or “humors”: phlegm, black bile, yellow bile and blood. Doctors and their patients believed that restoring health required a rebalancing of those humors through the draining of “excess” blood from the body.