Medieval Jewish intellectuals living in Muslim and Christian lands were strongly concerned to recover what they regarded as a 'lost' Jewish philosophical tradition. As part of this project they transmitted and produced many philosophical and scientific works and commentaries, as well as philosophical commentary on scripture, in Judaeo-Arabic and Hebrew, the principal literary languages of medieval Jewry. This volume presents new or revised translations of seven prominent medieval Jewish rationalists: Saadia Gaon, Solomon ibn Gabirol, Moses Maimonides, Isaac Albalag, Moses of Narbonne, Levi Gersonides, Hasdai Crescas and Joseph Albo - including, for the first time in English, the complete Falaquera abridgement of Gabirol's Source of Life. These works range over topics that are both theological (e.g. the creation of the world) and philosophical (e.g. determinism and free choice), but they are characterized by two overarching principles: the unity of truth, and its accessibility to human reason.