Michael Servetus (1511-1553). 19th century illustration of 16th century Spanish physician Michael Servetus (Michel Servet). As a physician, Servetus was the first European to describe the function of the pulmonary circulation, though it was not widely known at the time as it was published in a theological work (titled 'Christianismi Restitutio') in 1553. However, his theological thoughts were ultimately condemned as heretical, and he was burnt at the stake near Geneva, Switzerland.