Petrus Alphonsi

Origins and early life

Petrus Alphonsi was born about 1062 at Huesca in Muslim Spain as Moses Sephardi, a Jew educated in Hebrew, Arabic and the sciences of al-Andalus; he practised medicine and knew the astronomy of the Arab world at first hand.

Work and career

This fiche states plainly the turning point of his life: on 29 June 1106, the feast of Saints Peter and Paul, he was baptized in the cathedral of Huesca with King Alfonso I of Aragon standing as his godfather, and took the name Petrus Alphonsi from the saint and the king. He wrote afterwards a Dialogue against the Jews, in which his old self, Moses, argues with his new self, Peter — a polemic that was copied across Europe and used against his former community for centuries, and this fiche does not hide it.

His other work is why he is here. The Disciplina clericalis, a collection of thirty-three tales and fables drawn from Arabic, Hebrew and Persian sources and set in a frame of a father instructing his son, was the first substantial body of eastern storytelling to enter Latin Europe; it circulated in dozens of manuscripts and its stories reappear in Boccaccio, Chaucer, the Gesta Romanorum and Don Juan Manuel. He served as physician, by his own claim, to Henry I of England, taught in England and France, and wrote a Letter to the Peripatetics of France urging Christian scholars to abandon the astronomy they had and learn the Arabic science instead; he translated astronomical tables of al-Khwarizmi with Walcher of Malvern, and was among the first to bring the Indian numerals and the concept of zero into Latin.

He died after 1116. The whole transfer of Arabic learning to the medieval West begins with men like him, who could read three traditions.