Michael Servetus, also known as Miguel Servet, was a Spanish theologian, physician, cartographer, and Renaissance humanist. He was the first European to correctly describe the function of pulmonary circulation, as discussed in his book Christianismi Restitutio (1553). He was a polymath versed in many sciences: mathematics, astronomy and meteorology, geography, human anatomy, medicine and pharmacology, as well as jurisprudence, translation, poetry and the scholarly study of the Bible in its original languages.
When Juan de Quintana, an imperial theologian became Confessor to the Habsburg emperor Charles V, Servetus joined him in the imperial retinue as his secretary. Servetus travelled through Italy and Germany, and attended Charles‘ coronation as Holy Roman Emperor in Bologna. He was outraged by the pomp and luxury displayed by the Pope and his retinue, and decided to follow the path of reformation. It is not known when Servetus left the imperial entourage, but in October 1530 he was already spreading his theological beliefs.
In July 1531, Servetus published De Trinitatis Erroribus (On the Errors of the Trinity). The next year he published the work Dialogorum de Trinitate (Dialogues on the Trinity) and the supplementary work De Iustitia Regni Christi (On the Justice of Christ’s Reign) in the same volume. After the persecution of the Inquisition, Servetus assumed the name “Michel de Villeneuve” while he was staying in France and published the first French edition of Ptolemy’s Geography. Working also as a proofreader, he published several more books which dealt with medicine and pharmacology, such as his Syruporum universia ratio (Complete Explanation of the Syrups), for which he gained fame.
After an interval, Servetus returned to Paris to study medicine in 1536. During these years he wrote his Manuscript of the Complutense, an unpublished compendium of his medical ideas. Servetus taught mathematics and astrology while he studied medicine. He predicted an occultation of Mars by the Moon, and this joined to his teaching generated much envy among the medicine teachers. He was accused of teaching De Divinatione by Cicero. Finally, the sentence was reduced to the withdrawal of this edition. As a result of the risks and difficulties of studying medicine at Paris, Servetus decided to go to Montpellier to finish his medical studies, where he became a Doctor of Medicine in 1539.
After his studies in medicine, Servetus started a medical practice in Vienne, France, and he and John Calvin began to correspond. Calvin used the pseudonym “Charles d’Espeville.”
In 1553 Michael Servetus published another religious work with further anti-trinitarian views. It was entitled Christianismi Restitutio (The Restoration of Christianity), a work that sharply rejected the idea of predestination as the idea that God condemned souls to Hell regardless of worth or merit. God, insisted Servetus, condemns no one who does not condemn himself through thought, word, or deed. This work also includes the first published description of the pulmonary circulation.
To Calvin, who had written his summary of Christian doctrine Institutio Christianae Religionis (Institutes of the Christian Religion), Servetus’ latest book was an attack on historical Nicene Christian doctrine and a misinterpretation of the biblical canon. Calvin sent a copy of his own book as his reply. In time their correspondence grew more heated until Calvin ended it. Servetus sent Calvin several more letters, to which Calvin took offense. Thus, Calvin’s frustrations with Servetus seem to have been based mainly on Servetus’s criticisms of Calvinist doctrine, but also on his tone, which Calvin considered inappropriate.
On 16 February 1553, Michael Servetus was denounced as a heretic by Guillaume de Trie, a rich merchant in Geneva, and who was a good friend of Calvin, in a letter sent to a cousin. On behalf of the French inquisitor Matthieu Ory, Michael Servetus and Balthasard Arnollet, the printer of Christianismi Restitutio, were questioned, but they denied all charges and were released for lack of evidence. Ory asked Arneys to write back to De Trie, demanding proof. On 26 March 1553, the letters sent by Michel to Calvin and some manuscript pages of Christianismi Restitutio were forwarded to Lyon by De Trie.
On 4 April 1553 Servetus was arrested and imprisoned in Vienne. He escaped from prison three days later. On 17 June, he was convicted of heresy, “thanks to the 17 letters sent by John Calvin, preacher in Geneva” and sentenced to be burned with his books. In his absence, he and his books were burned in effigy (blank paper for the books).
Meaning to flee to Italy, Servetus inexplicably stopped in Geneva, where Calvin and his Reformers had denounced him. On 13 August, he attended a sermon by Calvin at Geneva. He was arrested after the service and again imprisoned. All his property was confiscated. French Inquisitors asked that Servetus be extradited to them for execution. Calvin wanted to show himself as firm in defense of Christian orthodoxy as his usual opponents. “He was forced to push the condemnation of Servetus with all the means at his command.” Calvin’s delicate health meant he did not personally appear against Servetus.
The council that condemned Servetus was presided over by Ami Perrin who ultimately on 24 October sentenced Servetus to death by burning for denying the Trinity and infant baptism. Calvin and other ministers asked that he be beheaded instead of burnt, knowing that burning at the stake was the only legal recourse. This plea was refused and on 27 October, Servetus was burnt alive—atop a pyre of his own books—at the Plateau of Champel at the edge of Geneva. Historians record his last words as: “Jesus, Son of the Eternal God, have mercy on me.”