In this era of open-heart surgery and medical research, science has amassed a great deal of knowledge on the function of the heart and blood. But prior to anaesthetics, blood transfusions and antiseptics, to open the chest and expose the heart meant certain death for the patient. The motion of the heart was poorly understood, yet the actions of one man, William Harvey, were to unravel its mysteries.The tale of this discovery is one of ingenuity, imagination and perseverance, and a remarkable use of experiment, observation and skill. In the seventeenth century, William Harvey, physician to King James I and Charles I, made one of the greatest discoveries in anatomy, revolutionising our understanding of the human body. He found that the blood vessels form a closed system and that the blood circulates rapidly around the body, pumped by the heart. Having stood unchallenged for 1,500 years, the accepted view - that blood was generated in the liver and slowly consumed by the body - was overthrown.Andrew Gregory's extraordinary account of Harvey's crucial work places it against the background of the art and science of the Renaissance, and narrates the dramatic struggle Harvey fought for its acceptance.