 Rabbi Hasdai Crescas (ca. 1340–1410/11) was the head of the Jewish community of Aragon, and in some ways all of Hispanic Jewry, during one of its most critical periods. Crescas was one of the leading rabbinic authorities of his  time,[1] the political leader of the Jews of Aragon, and a philosophical polemicist against Christianity. As one of the main medieval Jewish philosophers, Crescas critiques the radical Aristotelian philosophy of Maimonides and some of his philosophical heirs. He denounces the different Aristotelian opinions as contradicting not only the Jewish tradition, but also the true empirical and rational understanding of the world. Crescas assembles traditional Jewish opinion, the diverse Aristotelian sources, the neo-platonic thought of the apostate Abner of Burgos and the new science of scholastics of the 14th century to create an original philosophical opinion and critique of Aristotelianism known to the medieval period. His philosophical book Or Hashem was an important oeuvre of both Judaic thought and of the criticism of Aristotelian science which spurred the growth of the new science of the modern period, which arguably started in the 14th century. Until recently this book hadn’t been translated completely in any occidental languages, though it had influenced general occidental philosophy, especially via thinkers like Pico della Mirandola and Spinoza.