The Disputation or Cathechesis of Tortosa with its sixty-nine sessions (February 7, 1413-November 12, 1413) was the longest of the Jewish Christian encounters in the Middle Age. Stirred by the Avignonesian Pope Benedict XIII, Geronimo de Sancta Fide, olim Yehoshua ha-Lorki, summoned a group of Catalan and Aragonese rabbis to inform them that the Messiah was already came. Not only the Papal notaries recorded the excruciating debates, but also two Hebrew sources: the anonymous and fragmentary letter published by Halberstam in (...) 1868 and the chapter 40 of the Shebet Yehuda. They encompass the first nine sessions carried out orally, before the Pope requested for written texts to be debated lately. Since these sources disagree on many details, this paper aims at examining them anew. That examination has shown that the anonymous account is more accurate than the fictional report of the Shebet Yehuda as far as the internal chronology of the sessions, the speeches of the Jewish delegates and their identities are concerned. The internal evidence leads us to subscribe with Riera i Sans in ascribing its authorship to Bonastruc Desmestre from Girona, who was at Tortosa on request of the Pope. He probably knew other Jewish chronicle and added some new materials from the Vikkuach Ramban, Salomon Ibn Verga, the author of Shebet Yehuda, built upon this chronicle and created a fictional account around Vidal Benveniste or the ‘ideal’ portrait of the Pope and added some materials from the Latin Protocols or from unknown Jewish sources. (shrink)