Person

Maimonides

Moses ben Maimon (1138-1204), the Rambam, the most influential medieval Jewish philosopher and codifier of Jewish law, whose Guide for the Perplexed (Arabic Dalālat al-Ḥāʾirīn, c. 1190) is the high-water mark of Jewish-Aristotelian rationalism and whose Mishneh Torah (c. 1180) is the standard pre-modern codification of halakhah. On creation and the days of Genesis 1, Maimonides argues that time itself is a created reality and that the chronological reading of the six days is a category mistake, a position that converges decisively with the Augustine-Philo instantaneous-creation tradition while being independently developed from the Arabic-Aristotelian sources Maimonides inherited. The Rambam is one of the heaviest hitters in the historical record on the question of how Genesis 1 should be read.

Biography

Born 1138 in Córdoba, in the Almoravid caliphate of al-Andalus (Muslim Spain), to a distinguished rabbinic family. His father Maimon was a dayyan (rabbinic judge).
1148, the Almohad caliphate conquers Córdoba and imposes forced conversion (Islam or expulsion) on Jews and Christians. The Maimon family flees, wandering through southern Spain and Morocco for years.
c. 1166, settles in Fustat (Old Cairo), Egypt, after a brief stay in Palestine. Becomes physician to Saladin's vizier al-Qadi al-Fadil and effectively to the Sultanate; serves as Nagid (head) of Egyptian Jewry.
Died 1204 in Fustat. Buried in Tiberias, where his tomb remains a major Jewish pilgrimage site.

Major works

Commentary on the Mishnah (c. 1168), the earliest major work; written in Judeo-Arabic; introduces the famous Thirteen Principles of Faith (in the introduction to Pereq Heleq on Sanhedrin 10).
Sefer ha-Mitzvot (Book of Commandments, c. 1170), enumeration and classification of the 613 commandments.
Mishneh Torah (c. 1180), the comprehensive codification of halakhah in fourteen volumes. The first Jewish work to systematize the entire body of Jewish law topically rather than as commentary on the Talmud. Written in clean Mishnaic Hebrew (not Aramaic).
Dalālat al-Ḥāʾirīn / Moreh Nevukhim (Guide for the Perplexed, c. 1190), the philosophical magnum opus. Written in Judeo-Arabic for educated Jews struggling with the apparent conflicts between Torah and Aristotelian philosophy. Translated into Hebrew by Samuel ibn Tibbon (1204), into Latin (13th c.), read by Aquinas, Albertus Magnus, Meister Eckhart.
Treatise on Logic (Maqāla fī Ṣināʿat al-Manṭiq), handbook on Aristotelian logic for the student of philosophy.
Medical works, treatises on asthma, hemorrhoids, sexual hygiene, poisons; classical-Galenic medicine adapted to clinical practice.

Key positions

Creation: time is itself created

Guide for the Perplexed 2.30, one of the most influential rabbinic statements on Genesis 1:

"Time itself is among the things created… The whole of time itself was created."

"It should not be believed that 'in the beginning' [bereshit] implies the existence of a temporal beginning, for time itself belongs to the created things… You will never find anyone capable of finding the true sense of the verses dealing with the creation."

The argument:

Time is a property of moved bodies (Aristotelian Physics IV), therefore time cannot exist prior to the cosmos, since there are no moved bodies prior to creation.
"Days" in the modern temporal sense require a sun (the standard celestial clock). Therefore the first three "days" are not temporal in the modern sense.
The question "how long was the first day?" is malformed, it presupposes a clock that did not yet exist.
The creation account is intentionally esoteric, the Maaseh Bereshit ("Work of the Beginning") is one of the two restricted mystical subjects in Jewish tradition (the other being the Maaseh Merkavah, the Work of the Chariot).

This is the decisive Jewish-rationalist convergence with Augustine (Confessions XI; De Genesi ad Litteram), time is created with the universe; chronological language is retrospective; the days of Genesis 1 transcend modern duration-measurement. Maimonides reaches this conclusion independently of Augustine, via Aristotelian-Arabic philosophical sources (al-Farabi, Avicenna), not patristic ones.

Creation ex nihilo against Aristotle

Despite his Aristotelianism, Maimonides decisively rejects Aristotle's doctrine of the eternity of the world. In Guide 2.13-25, he argues:

Aristotle's arguments for an eternal world are demonstrative on his premises but not coercive on truer premises.
Mosaic revelation teaches creation ex nihilo, the world is finite in the past.
Creation ex nihilo is rationally defensible if not strictly demonstrable.

This is decisive for the Christian scholastic tradition: Aquinas (ST I q. 46 a. 1-2) takes essentially the same position, eternity of the world is not demonstrable either way; revelation settles it in favor of creation in time.

Apophatic / negative theology

Maimonides' doctrine of divine attributes (Guide 1.50-60) is the most radically apophatic ("via negativa") in the medieval tradition:

No positive attribute can be predicated of God univocally with creatures.
All scriptural anthropomorphism is accommodated language for human cognitive limits.
God is known by what He is not (not finite, not composite, not changing) rather than by what He is.
The 13 attributes of mercy (Ex 34:6-7) are descriptions of God's actions in the world, not of His essence.

This position influences Aquinas's qualified analogical predication, the Christian apophatic tradition (Pseudo-Dionysius, Eckhart), and the modern argument from apophatic convergence.

Prophetic accommodation

The biblical text is accommodated to the cognitive capacities of its audience. Prophets describe spiritual realities in physical language; later interpreters must recognize the accommodation and translate back. This is the rabbinic counterpart of Calvin's accommodation principle, same logic, different sources.

The Thirteen Principles of Faith

Maimonides' enumerated principles (in the introduction to Pereq Heleq) became the closest thing to a Jewish creed:

Existence of God
Unity of God
Incorporeality of God
Eternity of God
Exclusive worship of God
Prophecy
Supremacy of Moses among prophets
Divine origin of Torah
Immutability of Torah
God's knowledge of human affairs
Reward and punishment
Coming of the Messiah
Resurrection of the dead

These are sung in the daily liturgy as Ani Ma'amin and Yigdal. Note principle 3 (incorporeality), radically anti-anthropomorphic, sharply against any God-has-a-body theology (relevant against the LDS Godhead model, see Trinity §plural-Hebrew-noun stack).

Influence

On Jewish thought, the Rambam is the single most cited medieval Jewish philosopher in subsequent rabbinic literature. His Aristotelian-rationalist program was controversial in his lifetime (the Maimonidean Controversies of the 13th c. saw his books burned by some traditionalists), but became the philosophical mainstream from the 14th century forward.
On Christian scholasticism, Aquinas cites Rabbi Moses (his name for Maimonides) more than any other non-Christian thinker in the Summa Theologiae. Aquinas's positions on the indemonstrability of the world's eternity, the doctrine of analogical predication, the metaphysics of divine attributes, and the relation of philosophy to revelation are all in direct dialogue with the Guide.
On Islamic philosophy, Maimonides was read in Arabic by later Islamic philosophers (his Guide was originally written in Arabic with Hebrew letters).
On modern philosophy of religion, Spinoza (a Sephardic Jew of the Amsterdam community) responds to Maimonides; modern arguments for atheism, religious naturalism, and apophatic mysticism all engage Maimonidean categories.

On the days of creation, apologetic deployment

Maimonides supplies the classical Jewish-rationalist answer to the modern atheist objection that Genesis is falsified by cosmology. The objection presupposes a temporal-chronological clock that, on Maimonides' reading, is itself a created thing and therefore inapplicable to the moment of creation. The modern atheist trades on a category mistake the 12th-century rabbi already identified.

Combined with the patristic-Christian convergence (Philo, Augustine, Origen), this gives the apologist a remarkable historical position: the strictly-24-hour-solar-day reading is neither the patristic nor the rabbinic mainstream. The "literal/figurative" binary the atheist forces is itself the artifact of a much later (largely 20th-c. American evangelical) exegetical narrowing.