William Harvey (April 11, 1578 - June 3, 1657) was an English physician. Harvey was the first person to accurately determine how the heart circulated blood throughout human and animal bodies and 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' (full title: Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus, An Anatomical Exercise on the Motion of the Heart and Blood in Animals) remains a milestone in science. He was often so immersed in his own thoughts that he would often suffer from insomnia. A heavy drinker of coffee, he would walk out combing his hair every morning full of energy and enthusiastic spirit through the fields. He died in 1657 at the age of 79. Descriptions of the event seem to show that he died of a cerebral hemorrhage from vessels long injured by gout.