Michael Servetus (1511-53)
Michael Servetus was a theologian who also studied medicine in Lyons and Paris. In 1553 he anonymously published a 700-page book, Christianismi restitution (The Restoration of Christianity). His religious views were considered extreme, angering both Catholics and Protestants.
His description of the pulmonary transit of the blood through the lungs was part of his theological work. Servetus argued that as the soul resided in the bloodstream, one would need to study the origin and movement of blood in order to understand the soul.
Servetus challenged Galen's model of physiology, in which blood was produced by the liver and consumed by the body. Instead, he argued that blood became mixed with air, and therefore spirit, in the lungs.
Servetus’s religious views were considered so heretical that he was condemned for heresy, not only by the Catholic Inquisition, but also in Protestant Geneva, where he was burnt at the stake. Included in the bonfire that killed him were almost all the copies of his book, limiting its influence on the history of anatomy.