The interplay between kabbalah and medieval science requires a book-length study and years of future research. This chapter is offered not as a set of definitive conclusions but as a preliminary suggestion to frame the relevant issues. I begin by clarifying different notions of “science” in Aristotle and in the Judaic variant of the Platonic view found in Sefer Yeṣirah (SY). Next I discuss the reception of SY in medieval Jewish philosophy in the tenth to twelfth centuries, before the rise of kabbalah, under the influence of Ismaili philosophy. I proceed to document the interest of kabbalists in SY, which became a foundational text in kabbalah and the subject of many commentaries. I argue that kabbalah preserved a philosophical-scientific outlook – an Ismaili version of medieval Neoplatonism – that Maimonides and his followers had rejected when they promoted Aristotelian science as the only authoritative scientific paradigm. Thus, during the thirteenth century, kabbalah and philosophy presented two alternative approaches to science. Both were elitist programs, and both saw themselves as the repository of the hidden meaning of the revealed text. However, in the 1220s the rationalist philosophers renounced the commitment to esotericism and began to disseminate philosophy to the public, whereas kabbalah remained committed to esotericism at least until the early 1270s. Thereafter kabbalah “went public,” so to speak, in direct response to the dissemination of Aristotelian philosophy among the Jewish intelligentsia in Spain and Provence.

I illustrate the relationship between Aristotelian science and kabbalah by looking more closely at the polemical exchange about the origin of the universe between Jacob ben Sheshet and Samuel Ibn Tibbon during the 1230s. This exchange demonstrates that in the thirteenth century kabbalah was neither antiscientific nor ignorant of the science of its day, but rather that kabbalists subscribed to a Platonic notion of scientific knowledge and to a Neoplatonic cosmology that differed from the view of the Jewish Aristotelians. I conclude with a few reflections on the impact of kabbalah on the involvement of Jews in the natural sciences during the Late Middle Ages.