Hasdai ben Abraham Crescas was a Spanish-Jewish philosopher and a renowned halakhist. Along with Maimonides ("Rambam"), Gersonides ("Ralbag"), and Joseph Albo, he is known as one of the major practitioners of the rationalist approach to Jewish philosophy. 1340 – 1410; died at about 70. Alive at the same time as Johannes Gutenberg, Geoffrey Chaucer, Ibn Battuta, Jan Hus, and Jan van Eyck. Wiki link