human circulatory system in a detailed and systematic way. He did this by starting with a detailed study of blood flows into and out of the heart. Though some of his conclusions were based on inferences (not direct observation), they were conclusions based on logic and fact, not traditional understandings of circulatory systems. In fact, his rejection of contemporary medical orthodoxy—as well as moments where he was forced to rely on inferences—meant he was robustly discredited and attacked. It took several decades for his work to be fully accepted by the medical community.

Nevertheless, by his emphasis on reason and systemized study, Harvey contributed to advancing medical science in significant ways. He was also skeptical of superstition (for example, rejecting witchcraft) and looked instead for rational explanations of seemingly-supernatural phenomena.

English Physician William Harvey was one of the key figures of the Medical Renaissance, which coincided with the classical Renaissance. The Medical Renaissance was a period of revitalized interest in the medical discoveries of the Greeks and Romans, which European doctors reexamined to expand their own knowledge base.

Harvey was most famous for his work on heart and blood movement. Although he didn’t come up with the theory of pulmonary circulation, he did create the first quantitative argument for the pulmonary theory. Previously, most doctors believed blood to be food transformed in the liver rather than repumped. He provided the foundation for future work with the heart and circulatory system.