Medieval doctors spent 1000+ years convinced that perfect health meant balancing four magical body fluids: blood, phlegm, yellow bile, and black bile. Got a headache? Drain some blood. Feeling sad? More bloodletting. Broken leg? You guessed it—bloodletting. They were so obsessed with bodily fluids that they turned medicine into organized torture, complete with mercury poisoning, skull drilling, and enough leeches to stock a horror movie. Somehow, patients occasionally survived!