What is William Harvey best known for?

William Harvey (1578–1657) is best known for being the first to describe the full circulation of blood throughout the human body.123

His groundbreaking work, detailed in his 1628 book De Motu Cordis, fundamentally transformed the understanding of the cardiovascular system by demonstrating that the heart acts as a pump to circulate blood in a closed loop. This discovery contradicted the long-held Galenic view, which incorrectly suggested that blood was consumed by the body and continuously produced anew by the liver.143

Harvey supported his theory through quantitative experiments, measuring the volume of blood pumped by the heart to prove that the body could not possibly produce or consume such quantities so rapidly. Additionally, he made significant contributions to embryology, famously proposing the concept ex ovo omnia ("everything comes from the egg").43