Reading the Messiah off a Conjunction, and the Rabbi Who Refused

Masha'allah's claim that Jupiter-Saturn conjunctions track history did not stay a general theory of dynasties for long. Medieval Jewish astrologers turned the same mechanism onto the history and future of the Jewish people specifically. Abraham bar Hiyya, a twelfth century Catalonian mathematician and astrologer, set out in his Megillat HaMegalleh a detailed reading of Jewish history keyed to these conjunctions, connecting Moses's birth, his flight from Egypt and his years in Midian each to a specific planetary conjunction, and holding as a general rule that a conjunction occurring in the sign of Pisces signaled some calamity for the Jewish people. Solomon Ibn Gabirol, the eleventh century poet and philosopher, shared bar Hiyya's further conviction that the same mechanism could be used to calculate the timing of the Messiah's arrival, treating the conjunction cycle as a kind of hidden clock running through scripture and history together.

Not every serious astrologer of the age accepted this. Abraham Ibn Ezra, the influential twelfth century scholar who did as much as anyone to bring astrology into mainstream medieval Jewish culture, and who elsewhere credited planetary conjunctions with marking the births of major prophetic figures including Moses, Jesus and Muhammad, explicitly rejected the specific attempt to calculate the Messiah's coming from a conjunction date. The disagreement matters for what it shows: this was not a fringe superstition indulged uncritically, but a live technical argument among astrologers who took the underlying mechanism seriously and still split over how far it could honestly be pushed.

Kepler later linked the 7 BCE Jupiter-Saturn conjunction in Pisces to the birth in Matthew's Gospel; the idea predates him and comes from this dispute.