Illustration of truffle hunting from the Taqwim al-Sihhah, a medical treatise, written in the 11th Century by Ibn Butlan from Baghdad, based on the four humors. The four humors were black bile, yellow bile, phlegm, and blood. Greeks and Romans, and the later Muslim and Western European medical establishments that adopted and adapted classical medical philosophy, believed that each of these humors would wax and wane in the body, depending on diet and activity. An excess or deficiency of any of four distinct bodily fluids in a person directly influences their temperament and health. Muhammad said truffles are Manna which Allah sent to the people of Israel, and its juice is a medicine for the eyes. Terfezia was the main truffle consumed in the Middle East harvested in the mountains of Armenia and Turkey. Muslims used to boil them in water, cool and then use the water as eye drops. Ibn Butlan (1038 - 1075) was an Iraqi Christian physician of the Islamic Golden Age. He wrote the Taqwim al-Sihhah (The Maintenance of Health).