On the Motion of the Heart and Blood in Animals

William Harvey (1578-1657) was a rebel in medical science: Contrary to contemporary practice, he began his epoch-making investigation into the action of the heart and the blood's circulation by minutely observing their action in live animals and by a lengthy series of dissections, rather than by mere reliance on the anatomical lessons of ancient medicine and philosophy. "e;On the Motion of the Heart and Blood in Animals"e;, including explanations of heart valves and arterial pulse, stands as a triumph of true scientific inquiry, and is still regarded as one of the greatest discoveries in physiology.