Pope John XXI (1215 – May 20, 1277; Portuguese: Papa João XXI), born Pedro Julião (Latin, Petrus Iulianus), a Portuguese also called Pedro Hispano (Latin, Petrus Hispanus), was Pope from 1276 until his death about eight months later. He was the only Portuguese Pope, although Damasus I can also be considered Portuguese, as he was born in territory that is nowadays in Portugal, and Paul IV also had a Portuguese maternal grandmother.
He was also a physician, being the only pope ever to be so.
Note that the previous Pope named John was Pope John XIX (1024–32) as there was no Pope John XX.
Pedro Julião, born between 1210 and 1220, was probably born in Lisbon. He started his studies at the episcopal school of Lisbon Cathedral, and later joined the University of Paris, although some historians claim that he was educated at Montpellier. Wherever he studied, he concentrated on medicine, theology, and Aristotle's dialectic, logic, physics and metaphysics.
From 1245 to 1250 he became known as Pedro Hispano (because he came from Hispania, the Iberian Peninsula) and taught medicine at the university of Siena, where he wrote the Summulae Logicales, a reference manual on Aristotelian logic that remained in use in European universities for more than 300 years (see Peter of Spain for some controversies). He became famous as a university teacher, then returned to Lisbon. In the courts of Guimarães he was the councilor and spokesman of the king Afonso III of Portugal (1248–79) in church matters; later, becoming prior of Guimarães. He tried to become Bishop of Lisbon, but he was defeated. Instead, he became the master of the school of Lisbon. A notable philosopher, he was also the responsible for the creation of the Square of opposition.
Pedro became the physician of Pope Gregory X (1271–76). In March 1273 he was elected archbishop of Braga, but did not assume that post because on June 3, 1273 Gregory X created him Cardinal-Bishop of Frascati.
After the death of Pope Adria...