William Harvey (April 1, 1578 - June 3, 1657) was a doctor who first correctly described in exact detail the circulatory system of blood being pumped around the body by the heart. Many believe he discovered and extended early Muslim medicine especially the work of Ibn Nafis, who had laid out the principles and major arteries and veins in the 13th century.
Born in Folkestone, Harvey studied at Gonville and Caius College, Cambridge, receiving a BA in 1597, and then he studied medicine at the prestigious University of Padua under Fabricius, graduating in 1602. He returned to England and married Elizabeth Brown, daughter of the court physician to Elizabeth I. He became a doctor at St. Bartholomew's hospital in London (1609-43) and a Fellow of the Royal College of Physicians.
He announced his discovery of the circulatory system in 1616 and in 1628 published his work Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (An Anatomical Exercise on the Motion of the Heart and Blood in Animals), where, based on scientific methodology, he argued for the idea that blood was pumped around the body by the heart before returning to the heart and being recirculated in a closed system.
This clashed with the accepted model going back to Galen, which identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Venous blood was thought to originate in the liver and arterial blood in the heart; the blood flowed from those organs to all parts of the body where it was consumed. It was for exactly these reasons that the work of the "heathen" Ibn Nafis had been ignored.
Harvey's ideas were not accepted during his life-time. His work was attacked, notably by Jean Riolan in Opuscula anatomica (1649) which forced Harvey to defend himself in Exercitatio anatomica de circulatione sanguinis (also 1649) where he argued that Riolan's position was contrary to all observational evidence. Harvey was still regarded as an excellent doctor, he was personal physician to James I (1618-25) and Charles I (1625-47) and the Lumleian lecturer to the Royal College of Physicians (1615-56). Marcello Malpighi later proved that Harvey's ideas on anantomical structure were correct; Harvey had been unable to distinguish the capillary network and so could only theorize on how the transfer of blood from artery to vein occurred.
Even so, Harvey's work had little effect on general medical practice at the time — blood letting, an idea based on the incorrect theories of Galen, continued to be a popular practice. Harvey's work did much to encourage others to investigate the questions raised by his research, and to revive the Muslim tradition of scientific medicine expressed by Nafis, Ibn Sina and of course Rhazes.
Harvey also wrote De Generatione (1651), a Aristotelian exposition on mammalian generation.