Today, April 1, in 1578, was born an Englishman who turned the world of human physiology upside down. He was William Harvey. In his biography "William Harvey, A Life in Circulation", Thomas Wright calls him "one of the great heroes of the English Renaissance". Harvey was a contemporary of Shakespeare and Sir Francis Bacon. Jamestown was founded when he was not yet 30. He was part of a time of flux and ferment. On the high seas, European sailing ships were exploring distant lands. Harvey's streams flowed through the veins and arteries of the human body. He defined the circulatory system and lived to see his model of it upend centuries of devotion to the classical explanations of Galen.
Here is how Wright describes Harvey's revolutionary theory.
"Nor was Harvey criticizing the 'all-powerful Galen on specific points only. If true, his circulation theory would completely overthrow the Greek's concept of the function of the heart and the movement of the blood. Galen had held that there were two different types of blood and two almost entirely distinct vascular systems. Harvey was now proposing one of each. Where Galen's two systems were open, with most of the blood consumed by the muscles, tissues and organs and replaced continuously in the liver, Harvey was suggesting a closed system with the same blood flowing perpetually around the body. And while Galen had argued that the blood's movement within the vessels was in various directions, in a slow ebb and flow rather like the tides of the sea, Harvey claimed the blood coursed rapidly through the veins and arteries like a gushing river and in one direction only."
Happy 435th, Dr. Harvey!
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