On this date in 1553, Spanish physician Michael Servetus, ne Miguel Serveto, was executed for heresy by order of John Calvin, in Geneva, Switzerland. The anti-Trinitarian and rationalist published the first correct explanation of how blood circulates in the body. Born in 1511, Serveto grew up near Aragon, and studied law at the University of Toulouse in France, where he first read the bible, only newly available in printed form. Struck by the absence of mention of the trinity in the bible, and repelled by the excesses of the Roman Catholic Church, he turned to Protestantism. Its proponents also cast him out for his views. The Supreme Council of the Inquisition in Spain summoned him to return to Spain, a sure death sentence. In Paris, Servetus met a young student, John Calvin, who at one time was forced himself to go into hiding for heresy. Servetus studied medicine at the University of Paris, where he published the first work accurately describing pulmonary circulation. Servetus practiced medicine for 12 years in Vienne. In 1546, he began a fateful, heated correspondence on the trinity with his former acquaintance, Calvin. Calvin wrote a colleague that if Servetus should ever visit Geneva, "if my authority is of any avail I will not suffer him to get out alive." Servetus published Restitutio under a pseudonym in 1553, including in it 30 of his letters to Calvin. When he sent Calvin a copy, Calvin exposed Servetus' identity to the Catholic Inquisition in Vienne. Arrested and interrogated, Servetus escaped prison, but was arrested in Geneva while traveling to Italy. The Council of Geneva convicted him of antitrinitarianism and opposition to child baptism. Calvin lobbied for a beheading; the Council sentenced him to be burned at the stake. Only 3 copies of Servetus's Restitutio survived. In it, he rejected original sin and salvation, vicarious atonement and Christ's dual nature.