Saadiah Gaon (882–942) was a prolific and pioneering teacher, sage, and communal leader who pursued his wide-ranging studies with a singleminded commitment. His was the first Rabbanite translation of the Hebrew Bible into Arabic; his was one of the first Hebrew dictionaries; his Siddur marked one of the first attempts to regularize the liturgy. His Kitāb al-Amānāt wa l-I'tiqādā (Book of Beliefs and Opinions) was the first major work of medieval Jewish philosophy. Written during his renowned forced retirement in the year 932 C.E., the Kitāb al-Amānāt represents the beginning of a long and noble tradition of Judeo-Arabic philosophy.

Although there has been much in modern scholarship written about the historical and theosophical background of the Zohar, scholars have paid little attention to the literary structure of the work and its relationship to the thematic content contained therein. There is, as far as I know, not one in-depth study of such a nature.

Both the Bible and the earliest Greek philosophers begin with accounts of the world's genesis. It is thus not surprising that medieval cosmological thought was preoccupied, perhaps obsessed, with the issue of creation. But what about the end of the world? If the universe had a beginning, does it necessarily have an end? Does creation imply destruction? On this topic the Bible is not so explicit and unambiguous. Greek philosophy, however, was virtually unanimous in claiming that whatever has a beginning will have an end, and that whatever will have an end had a beginning. If this cosmological principle is construed strictly, then the world's past and its future are essentially and necessarily linked together, such that the finitude of one entails the finitude of the other. This would mean that if the temporal history of the world is finite a pane ante, then by virtue of this cosmological principle it will have a temporal end a pane post. The most vigorous and detailed defense of the strict interpretation of this general principle was given by Aristotle, who attempted to prove it in his treatise On the Heavens. Henceforth, I shall refer to this principle as “Aristotle's theorem.”

Amongst the most important roles which Isaac Luria (1534–1572), the preeminent kabbalist of sixteenth-century Safed, played in the lives of his disciples was that of physician of the soul. Before they could practice rituals which were intended to enable them to bind their souls to the divine realm, and to “repair” that realm in accordance with the teachings of Lurianic mythology, his disciples had first to mend their own souls, to cleanse and purify them of all imperfection No individual whose own soul had failed to achieve a certain level of perfection could hope to engage successfully in the intricate and elaborate contemplative rituals-such as the Yiḥudim-which Luria devised. A person had to undergo a period during which he cultivated certain spiritual and moral traits and atoned for whatever sins he might have committed. Luria, in fact, provided his followers with highly detailed rituals of atonement by which they were to mend their souls. These penitential acts were known as tikkunei avonot (“amends of sin”) whose purpose, in the words of Hayyim Vital's son Shmuel, was to “mend his soul"”and “cleanse him from the filth of the disease of his sins.” Hayyim Vital (1542–1620), Luria's chief disciple, himself introduces the tikkunei avonot with a discussion of the relationship between one's soul and sin.