Much later (1628) the Englishman William Harvey discovered that blood is pumped by the heart, travels through the body in blood vessels, and returns back to the heart in the circulatory system. Thus basic facts of anatomy and physiology began to be understood by physicians. However, Harvey's work belongs to a later period. At the beginning of the period, in 1400, doctors were ignorant of physiology and had some (to us) pretty strange ideas. 