Galen was a renowned physician during the Middle Ages who made important contributions to anatomy, physiology, pathology and neurology among others. He developed the idea of Hippocrates of the 4 humours of black bile, yellow bile blood and phlegm. He studied the hearts of animals and found that the heart pumped the blood throughout the body. He considered that warm foods caused yellow bile and cold foods caused phlegm. Black bile was associated with the gall bladder and resulted in a melancholic mood.