In late July 1263 a public disputation was convened by King James I of Aragon, pitting Friar Paul Christian against the distinguished rabbi of Gerona, Moses ben Nahman.
Two accounts of the disputation, one in Hebrew written by Nachmanides and a shorter one in Latin, are the main sources for the history of this important episode in Judeo-Christian polemics. According to both sources the initiative for the disputation and its agenda were imposed by the Christian side, although the Hebrew account suggests greater involvement by Nachmanides in finalizing the items to be discussed. The initiative in the debate remained on the Christian side throughout.
On Friday, July 20, 1263, a remarkable assemblage was convened at the royal palace in Barcelona, consisting of King James himself, royal officials, barons, ecclesiastical dignitaries, leading burghers, and Catalan Jews.
The gathering was surely impressive, colorful, and—for the Jews involved—somewhat frightening. The purpose of this convocation was to witness an unusual public colloquy between a Dominican friar and the rabbi of Gerona. The Dominican, Friar Paul Christian, had been born a Jew, had converted, had entered the Dominican Order, had taken a role of leadership in considerable anti-Jewish activity, had in particular been zealous in developing a new line of Christian argumentation to be used against the Jews, and had won ecclesiastical and royal backing for convening this public debate. Friar Paul’s opponent, Rabbi Moses ben Nahman of Gerona, (Rabbi Moses ben Nahman, know as Ramban, Nahmanides, El Gerondi, or by his Catalan name Bonastrug Da Porta) was by this time a recognized authority in Catalan Jewry and, indeed, beyond the boundaries of Catalonia. He was, in fact, one of the giants of thirteenth-century Jewish life, distinguishing himself as a talmudic authority, a central figure in the rising mystical circles on the Iberian peninsula, and a communal leader of sensitivity and acumen.