Pedro Julião was born in
Lisbon between 1210 and 1220 to Julião Pais and Mor Mendes. His father was chancellor of
Afonso Henriques and
Sancho I. 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,
logic,
physics,
metaphysics, and
Aristotle's
dialectic. He is traditionally and usually identified with the medical author
Peter of Spain, an important figure in the development of logic and
pharmacology. Peter of Spain taught at the
University of Siena in the 1240s and his '''' was used as a university textbook on
Aristotelian logic for the next three centuries. At the court in Lisbon, he was the councilor and spokesman for
King Afonso III in church matters. Later, he became
prior of Guimarães. He was Archdeacon of Vermoim (Vermuy) in the Archdiocese of Braga. He tried to become
bishop of Lisbon but was defeated. Instead, he became the Master of the school of Lisbon. Peter became the physician of
Pope Gregory X (1271–1276) early in his reign. In March 1273, he was elected Archbishop of
Braga, but did not assume that post; instead, on 3 June 1273,
Pope Gregory X created him
Cardinal Bishop of Tusculum (Frascati). ==Papacy==