William Harvey made the momentous medical discovery that the flow of blood must be continuous and that its flow must be in one direction only. This discovery sealed his place in the history of medicine.


William Harvey was born in 1578 in Folkestone, Kent. Harvey studied at Caius College, Cambridge before he enrolled at the University of Padua in 1598. At the time when Harvey was a student at Padua, Galileo was a tutor there and there is little doubt that he was highly influenced by the Galilean way of thinking that enthused the university as a whole. Harvey learned about the human body by dissection and anatomical observation.


Harvey’s primary tutor at Padua was Fabrizio d’Acquapendente who was the first person to clearly describe the valves in the veins.


In 1602, Harvey returned to London to live. He married the daughter of Lancelot Browne, who had been physician to Elizabeth I and on Harvey’s return was physician to James I. He joined the staff at St. Bartholomew’s Hospital and became a reader in anatomy and surgery. Harvey also continued his study into the vascular system and in 1616 he announced his discovery of the circulation of blood within the body. However, it was not until 1628, that Harvey’s work ‘Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus’ was published in Frankfurt.


Harvey explained how blood flowed in one direction throughout the body and that it was in the lungs where the transformation of venous blood to arterial blood took place.


Galen had always believed that the liver was the centre of circulation within the body. Some practitioners had hinted at their rejection of this idea but it was Harvey who specifically refuted it and put his research into a written document. Harvey was lucky to live in the era when he did. In 1553, a Spanish doctor and theologian, Michael Servedo (Servetus) published ‘Christianismi Restitutio’, which went against Galen’s ideas, which had the support of the Catholic Church, and many years before Harvey, moved in the same direction as his ideas as announced in 1616. Servedo was burned at the stake for heresy. An unpredictable Tudor England would not have been a good time for Harvey to have made his findings known.


As well as Servedo, men such as Leonardo, Vesalius and Cesalpino may also have been moving towards what Harvey was to prove. However, Harvey’s great achievement was to actually write in depth and clarity about his findings. He backed his findings with explanations of experiments he had carried out. Harvey stated that he believed that the heart was a pump and that it worked by muscular force. Harvey wrote about what he had seen during his experiments, such as the contraction of the walls of the heart cavities at the moment when they emptied of blood (systole) and the dilation of the cavities when filled (diastole). He observed and wrote about his experiments when he observed a vein swell below a ligature. His work was a major advance in Man’s knowledge of the cardio-vascular system.


William Harvey’s fame was such that he became the court physician to Charles I who took a great interest in his work on circulation.


In 1651, Harvey’s second major piece of work, ‘De Generatione Animalium’, was published. This work concentrated on embryology and its importance is based on the fact that it contained the theory of ‘epigenesis’ – that the organism does not exist as a minute, preformed entity within the ovum but develops from it by a gradual building up of its parts. Von Baer confirmed this belief in the Nineteenth Century. However, he had the advantage of using the microscope.


Harvey’s one major mistake concerned fertilisation, which he believed to be something akin to mysticism and metaphysical. Harvey likened fertilisation to the magnetism transferred from one piece of metal to another. However, there can be little doubt that if Harvey had had access to a microscope he may well have concluded differently.


Harvey made one major medical discovery but possibly his lasting legacy in terms of medical practice was his belief in experiments to prove or disprove what you believed in. His approach was to greatly influence men such as Robert Boyle, Robert Hooke and Richard Lower.


William Harvey died in 1657.