Almost five hundred years after his death, Don Isaac Abravanel (1437-1508) remains a legendary figure of Sephardic history, and above all of the Expulsion of 1492. There are numerous "portraits" that have been painted of him by pre-modern and modern scholars. And still we hesitate and cannot discern which is the true one. This first critical edition of Abravanel's Portuguese and Hebrew letters opens a unique window on a complex cultural process of assimilation and dissimulation of humanism among the fifteenth-century Jewish elite. On the one hand, it establishes Abravanel's assimilation of Iberian humanism and of major aspects of the Petrarchian consolatio; on the other hand, it points at the strategies used by him to dissimulate and adapt humanism to Jewish leadership. The duality of Jewish humanists like Don Isaac was obviously a great richness, but it indicated as well their difficulty in expressing themselves coherently and comprehensively in one of the two agoras - Jewish or Christian - in which they were involved as literati and writers. The present edition and study of Abravanel's Portuguese and Hebrew letters sheds a new light on the complexity of this new figure of the Jewish humanist.