My humble answer: I believe Hippocrates came from a medical family that believed there was a physiological cause to disease. His school of medicine was actually one of the first in history not to believe that diseases were caused by evil spirits. Likewise, he was among the first to try to find real remedies to diseases rather than simply chanting and praying. He believed diseases were the result of an imbalance of the four humors in the body: phlegm, yellow bile, black bile and blood. If he believed a disease condition was caused by too much blood, his cure was to bleed the victim. While his theory of diseases was incorrect, it was pretty much taught for the next 2,000 years.