Light of the Lord

The main philosophical work of Hasdai Crescas, a leading rabbi of Aragon, completed in 1410, two decades after the anti-Jewish riots of 1391 in which his son was killed. Written in Hebrew, it is a systematic account of Jewish belief and a direct challenge to the Aristotelianism of Maimonides. In its first part Crescas examines the premises of Aristotelian physics that Maimonides had used to prove God's existence, and argues that an actual infinite is possible, that a void can exist, and that place is extension rather than the boundary of a containing body, so that several of the proofs fail. He then reorganises the principles of faith, holding that God's perfection lies in love and joy rather than intellect alone, and develops a view of human choice that admits causal determination while preserving responsibility. Spinoza knew the work, and Harry Wolfson's study made its physics famous among historians of science.

It is the most powerful medieval critique of Aristotle's physics from within a religious tradition, and its treatment of infinity and of free will repays comparison with Spinoza.