Levi ben Gershom (Hebrew: לוי בן גרשום‎), better known as Gersonides or the Ralbag (1288-1344), was a famous rabbi, philosopher, mathematician, astronomer/astrologer, and Talmudist. He was born at Bagnols in Languedoc, France.

Biography

Works
Part of his writings consist of commentaries on the portions of Aristotle then known, or rather of commentaries on the commentaries of Averroes. Some of these are printed in the early Latin editions of Aristotle's works. His most important treatise, that by which he has a place in the history of philosophy, is entitled Sefer Milhamot Ha-Shem , ("The Wars of the Lord"), and occupied twelve years in composition (1317—1329). A portion of it, containing an elaborate survey of astronomy as known to the Arabs, was translated into Latin in 1342 at the request of Pope Clement VI.
The Wars of the Lord is modeled after the plan of the great work of Jewish philosophy, the Guide of the Perplexed of Maimonides. It may be regarded as a criticism of some elements of Maimonides' syncretism of Aristotelianism and rabbinic Jewish thought. The Wars of the Lord review:
1. the doctrine of the soul, in which Gersonides defends the theory of impersonal reason as mediating between God and man, and explains the formation of the higher reason (or acquired intellect, as it was called) in humanity — his view being thoroughly realist and resembling that of Avicebron;
2. prophecy;
3. and 4. God's knowledge of facts and providence, in which is advanced the theory that God does not know individual facts. While there is general providence for all, special providence only extends to those whose reason has been enlightened;
5. celestial substances, treating of the strange spiritual hierarchy which the Jewish philosophers of the middle ages accepted from the Neoplatonists and the pseudo-Dionysius, and also giving, along with astronomical details, much of astrological theory; and
6. creation and miracles, in respect to which Gersonides deviates widely from the position of Maimonides.
Gersonides was also the author of a commentary on the Pentateuch and other exegetical and scientific works.

Views on God and omniscience
Gersonides posits that people's souls are composed of two parts: a material, or human, intellect; and an acquired, or agent, intellect.. The material intellect is inherent in every person, and gives people the capacity to understand and learn. This material intellect is mortal, and dies with the body. However, he also posits that the soul also has an acquired intellect. This survives death, and can contain the accumulated knowledge that the person acquired during their lifetime. For Gersonides, Seymour Feldman points out, "Man is immortal insofar as he attains the intellectual perfection that is open to him. This means that man becomes immortal only if and to the extent that he acquires knowledge of what he can in principle know, e.g. mathematics and the natural sciences. This knowledge survives his bodily death and constitutes his immortality." (Gersonides, Trans. Seymour Feldman Wars of the Lord, Book 1, p. 81, JPS, 1984)

Works in mathematics and astronomy/astrology

"Gersonides". The Encyclopaedia Judaica. Keter Publishing.
Eisen, Robert (1995). Gersonides on Providence, Covenant, and the Chosen People: A Study in Medieval Jewish Philosophy and Biblical Commentary. State University of New York.
Guttman, Julius (1964). Philosophies of Judaism, p.214/215. JPS.
Feldman, Seymour. The Wars of the Lord (3 volumes). Jewish Publication Society.