Petrus Alfonsi

Petrus Alfonsi was an Andalusian polemicist and translator who flourished, on the Encyclopaedia of Islam's dating, from 1106 to about 1130, and who converted to Christianity in 1106. ¹ He is a figure of the Latin transmission of Arabic learning: he wrote an anti-Jewish dialogue whose chapter on Islam later Latin authors drew on, adapted an Arabic astronomical table into Latin, and compiled a collection of tales that carried stories of Arabic origin into European literature. ¹

The article on orientalists says the first written information about Islam and Muhammad in this milieu comes from a certain Moses Sefardi, who knew Arabic astronomical works well. It gives his years as 1062 to 1110, says he converted to Christianity in 1106 and took the name Pedro de Alfonso, and adds that he then moved to England, where he became the king's personal physician. The same passage notes that this information comes from the fifth chapter of his Dialogi and that little is known of the author. ²

The article devoted to him is more cautious about dates. It gives his period of activity as about 1106 to about 1130 and does not give a birth or a death. ¹ The two articles therefore disagree: one ends his life in 1110, the other has him active until about 1130. The museum records both and does not choose between them. The articles read do not name his town of origin, so the museum does not state one.

According to the article, he composed the Dialogi contra Iudaeos in 1108 or 1110. The work is staged as a debate between his former Jewish self, called Moses, and his present Christian self, called Peter. It ridicules Talmudic aggadah by showing that it contradicts principles of Graeco-Arabic philosophy and science, astronomy in particular. The article calls it the most widely read anti-Jewish text of the Latin Middle Ages. ¹

In the fifth chapter of the Dialogi, Alfonsi attacks Islam, following to a large extent an Arabic text attributed to 'Abd al-Masih ibn Ishaq al-Kindi. The article says he presents Muhammad as a charlatan driven by lust and political ambition, poorly taught in religious matters by a heretical Christian, Sergius, whom the article links to the story of Bahira, and by two heretical Jews, Abdias, identified with 'Abd Allah ibn Salam, and Chabalahabar, identified with Ka'b al-Ahbar. ¹ The same passage says he gives a curious description of pre-Islamic cult rituals at Mecca, apparently based on Spanish Jewish sources, and claims that current Islamic practice is tainted by these pagan origins. Later Latin writers on Islam used his tract extensively. ¹

This is the article's summary of a medieval polemic, set down so that readers can see how Islam was portrayed in twelfth-century Latin writing. It is not a view the museum holds, and the portrait of the Prophet ﷺ it describes is Alfonsi's, not a description of him by Muslim sources.

The article says Alfonsi taught astronomy in England and France. In 1116 he produced what the author calls an inept Latin adaptation of the Zij al-Sindhind of al-Khwarizmi; afterwards Adelard of Bath, probably with Alfonsi's help, produced a somewhat better version. ¹ He later wrote an Epistola ad Peripateticos, urging French scholars to study astronomy and arguing that Arabic texts are superior to those of Latin authors such as Macrobius. The modern edition of the Sindhind translation is listed in the article as that of O. Neugebauer. ¹

The Disciplina clericalis is a collection of proverbs, each followed by a short illustrative fable. The article calls it one of the earliest Latin texts to contain stories of Arabic provenance. It stayed extremely popular for centuries, in Latin and in many vernacular translations; preachers used its fables as exempla, Boccaccio incorporated some into the Decameron, and they reappeared in the fifteenth and sixteenth centuries in printed editions of Aesop. ¹

A separate Encyclopaedia of Islam article, on Luqman, mentions the work in passing. It notes that in the Disciplina clericalis the biblical Balaam is described as called Lucaman in Arabic, as an example of the old identification of Luqman with Balaam, and it calls the author a Spanish Jewish apostate. ³

The article's bibliography names K.-P. Mieth's 1982 Berlin dissertation as the best edition of the Dialogi, the older edition in Migne's Patrologia Latina, the Hilka and Soderhjelm edition of the Disciplina clericalis, and J. Tolan's study of Alfonsi and his medieval readers. ¹

The articles read give no birth or death year, no birthplace and no account of where he is buried. They also leave open whether the Moses Sefardi of the orientalists article and the Petrus of the personal article differ in dates because of different sources; only the names and the year of conversion agree. ^{2 1}