William Harvey was a physician and scientist in the 16th and 17th centuries who was the first to demonstrate how the circulatory system worked. He described how the arteries, veins, valves, lungs, and heart worked to circulate blood – and he was amazed at God's design and purpose in the systems of the body. He enjoyed studying how God had made things to work.
Harvey considered science a godly vocation and was motivated by the idea that the Creator had made things in an orderly way that could be understood and studied.
Harvey’s primary achievement, the explanation of the circulation of the blood, was occasioned in part “by asking why God put so many valves in the veins and none in the arteries.” He believed that nature does nothing “in vain.”
He was physician to King James 1 and King Charles. He was also the first to propose that humans and mammals reproduced by a sperm fertilizing an egg.