Harvey’s discovery of the circulation of the blood, first time in English:
Harvey concluded a series of brilliant teachers and students at the medical school of Padua which included Vesalius, Colombo, and Fabricius Acquapendente (a friend of Galileo’s).
In this work, the first English translation of De motu cordis (1628), Harvey marshaled a combination of quantitative, experimental, teleological and analogical arguments to prove the theory of the circulation of the blood.
One of the earliest clues that initially led Harvey to theorize that the motion of the blood through the heart and body might complete a circulation, rather than merely ebb and flow, was Acquapendente’s demonstration of valves in the veins. Harvey’s case for the circulation of the blood also relied upon a quantitative argument based on the total amount of blood flow and several experiments involving the observable flow of blood through the veins of the arm. Where possible, Harvey relied upon the anatomical tradition of “ocular demonstration” or autopsia, in which an empirical proposition is made undeniably evident to the senses. Yet he was not able to discern the capillaries, the tiny vessels in body tissues connecting the smallest arteries and veins, which were demonstrated with the microscope by Marcello Malpighi in 1661.
William Harvey (1578-1651), later a physician to King Charles I, published De motu cordis (On the Circulation of the Blood) in 1628. This is the first English translation.
For Harvey, blood flows through the heart and body in a continuous, unidirectional circulation. Starting from the left side of the heart, refined blood flows to the arteries of the body. From the arteries it passes to the veins, from which the blood moves back to the heart. Then from the right side of the heart it travels into the lungs before returning to the left side of the heart, completing a circulation.
Throughout Europe in the following decades Harvey’s work became the focus of debate and controversies over the use of empirical observations, even artificially contrived experience like dissections and experiments, in the demonstration of theories in natural philosophy.