Title page of "Exercitatio anatomica de motu cordis et sanguinis in animalibus." [On the motion of the heart and blood in animals.] by William Harvey, 1628. William Harvey (April 11, 1578 - June 3, 1657) was an English physician and the first person to accurately determine how the heart circulated blood throughout human and animal bodies. He was also the first to posit the theory that humans and other mammals reproduced when an egg was fertilized by sperm. His work "De Motu Cordis" remains a milestone in science.