Various Jewish thinkers, however, have proposed a "finite God", sometimes in response to the problem of evil and ideas about free will. Louis Jacobs writes that modern Jewish thinkers such as Levi Olan, echoing some classical Jewish writers such as the 14th-century Talmudist Gersonides have "thought of God as limited by His own nature so that while He is infinite in some respects he is finite in others", referencing the idea, present in classical sources, that "there is a primal formless material co-existent with God from all eternity upon which God has to work, and that God only knows the future in a general sense, but not how individual men will exercise their choice". On the topic of omniscience and free will, Jacobs writes that in the medieval period, three views were put forth: Maimonides, who wrote that God had foreknowledge and man is free; Gersonides, who wrote that man is free and consequently God does not have complete knowledge, and Hasdai Crescas, who wrote in "Or Adonai" that God has complete foreknowledge and consequently man is not really free.