Galen

   Medical theorist born in Pergamon (q.v.) ca. 130 (died ca. 200) whose medical treatises were the basis of medicine in Byzantium (q.v.), indeed throughout the entire intellectual world of the Middle Ages. The secret of his success in Byzantium (though he had been a pagan) was his belief that everything in the human body was formed by a creator for a particular purpose. This fit in well with Christian theology. Thus, his theory of the four body-fluids called humours and their alleged relationship to different temperaments and diseases and his physiology, which had the blood ebbing and flowing (not circulating) through the expansion and contraction of the right side of the heart, were never challenged. The great Byzantine physicians, e.g., Oribasios, Aetios of Amida, Alexander of Tralles, Paul of Aegina, and John Aktouarios (qq.v.) only summarized and commented on his ideas.