Sefer Yesirah

Besides these literary monuments of the Merkabah gnosis, there was another, extremely curious text which circulated widely during the Middle Ages, exercising a great influence in many lands and in diverse circles: the “Book of Creation,” Sefer Yesirah. Concerning the origin and spiritual home of this work, which numbers only a few pages, divergent opinions have been voiced, although to date it has been impossible to come to any reliable and definitive conclusions. This uncertainty is also reflected in the various estimates of the date of its composition, which fluctuate between the second and the sixth centuries. This slender work is also designated in the oldest manuscripts as a collection of “halakhoth on the Creation,” and it is not at all
The Book Yesirah was studied in the schools of the sages of Narbonne as well as among the French rabbis of the school of the tosagists and among German Hasidim of the same period, and many commentaries have come down to us from these circles, which were generally averse to philosophic speculation. It offers remarkable parallels to the turn which the Kabbalists gave to the doctrine of the sefiroth. It is no longer possible to say with certainty to what extent the study of the Book Yesirah was regarded in these circles as an esoteric discipline in the strict sense of the term. Perhaps one could view them as situated at the limits of esotericism, partly within it, but partly already beyond
As with many mystics, the facts of Moses’ life are scarce. In one of his books, he calls himself “Moses son of Shem Tov from the city of Leon.” The year of his birth is unknown, but by 1264 he was engaged in the study of philosophy, for in that year a Hebrew translation of Maimonides’ Guide of the Perplexed was copied “for the erudite Rabbi Moses de Leon.” Philosophy, however, was not Moses’ only undertaking. He immersed himself in rabbinic literature and was also drawn to the teachings of Kabbalah. For many centuries the word was used quite generally, but by the time of Moses de Leon, the term Kabbalah denoted esoteric teachings, techniques of meditation, and a growing body of mystical literature. A Kabbalistic movement had emerged in Provence and Catalonia toward the end of the twelfth and the beginning of the thirteenth centuries. The famous rabbi Nahmanides of Gerona explored the teachings and helped Kabbalah gain wider acceptance. The movement spread westward to Castile. Wandering south from Leon, Moses came to know some of the kabbalists and was introduce to the Bahir, the main text of Provencal Kabbalah, to the teachings of the school of Gerona, and to more recent Castilian formulations. Moses de Leon did not reject philosophy. Many of his kabbalistic comrades had also studied the Guide of the Perplexed, and there were parallels and connections between Maimonides’ system and Kabbalah. Both adopted the Neoplatonic scheme; both aimed at