The Hebrew text known as the Sefer Yeṣirah, or Book of Formation, has piqued the interest of scholars of early medieval Jewish philosophy and those of central- to late-medieval Jewish mysticism and magic for centuries. In Sefer Yeṣirah and Its Contexts: Other Jewish Voices, Tzahi Weiss extends interest in this text to scholars of early medieval Jewish mysticism, magical praxis, and Jewish-Christian relations. Through an exploration of Sefer Yeṣirah’s specific methods of letter speculation, grammar, and textual reception, Weiss presents a two-pronged argument. First, he contends that the much-debated compositional context of the Sefer Yeṣirah was most likely 7th-century Christian Syria. And, second, that early readers of the Sefer Yeṣirah understood it as a mystical and magical treatise long before the late 12th century, as is commonly assumed.

Weiss divides his slim volume into an introduction, five chapters, an epilogue, and two appendices. The first appendix addresses scholarly arguments that the Sefer Yeṣirah originated in the Abbasid world and was influenced by Arabic grammar; the second appendix provides a Hebrew transcription of an 11th-century recension of the Sefer Yeṣirah (Ms. Vatican 299/4) that Weiss bases his arguments on, accompanied by Peter A. Hayman’s English translation. Along with a review of scholarship treating the text and a statement of Weiss’ departure from, indebtedness to, and contributions to the field, the Introduction provides a quick summary of the contents of the Sefer Yeṣirah as a treatise describing God’s formation of the world from numbers (sefirot) and the letters of the Hebrew alphabet. The concept of sefirot is minimal within the Sefer Yeṣirah and Weiss relegates his discussion of them to his introduction.

The first three chapters that follow focus on modes of letter speculation and grammar as means of contextualizing the Sefer Yeṣirah. Chapter One discusses the widespread antique and early medieval beliefs that letters formed, or were synonymous with, the building blocks of creation. According to Weiss, alphabetical-elemental association probably originated in the ancient Near East and was commonly articulated in the Roman Mediterranean and Levant from the 1st century C.E. on. Although letter speculation and the belief in the generative efficacy of letters would remain viable within Jewish mystical and rabbinic literature, Weiss contends that these fell out of favor among patristic defenders of Christian orthodoxy and Neoplatonists during the first centuries C.E. Such beliefs did, however, survive and continue to develop among Gnostics and, more importantly for Weiss’ argument, a sect practicing a “marginal” form of Christianity in Syria.

Chapter Two is a synopsis of traditional Jewish letter speculation in regard to creation. Weiss illustrates that Jewish rabbinic and mystical sources predominantly viewed either the ineffable name (יהוה), transliterated as Yahweh, or one or more of the individual letters of the divine name, as the building blocks of creation. The rest of the Hebrew alphabet was largely insignificant within Jewish letter speculation. The overall aim of Chapter Three is to underscore the difference between traditional Jewish sources and the Sefer Yeṣirah, to highlight Syriac Christian influence on the author/s of this undeniably Jewish text, and to provide an approximation of the period of composition. Weiss holds that the Sefer Yeṣirah differs from traditional Jewish sources in regard to terminology, argumentation, a lack of references to Jewish luminaries of yore, and its main premise. The Sefer Yeṣirah theorized that God employed all 22 letters of the Hebrew alphabet, which it placed into three categories: the obscure classification of immot, “double letters,” and “simple letters.” The significance of the entire alphabet, its categorization, and especially the mention of “double letters” is similar to Syriac grammar that developed during the late-6th to 7th centuries in the wake of Syriac translations of ancient Greek grammatical treatises. Thus, Weiss places the compositional context of the Sefer Yeṣirah just slightly later, in the 7th-century Northern Mesopotamian era of bourgeoning Syriac letter speculation and grammatical theorization.

The final two chapters discuss the reception of the Sefer Yeṣirah during the early through central Middle Ages. Chapter Four notes, and reflects upon, the paucity of references to the Sefer Yeṣirah before the 10th- and 11th-century commentaries of Jewish luminaries who framed it as a scientific-philosophical treatise. By analyzing a gloss found within the Sefer Yeṣirah and a letter by the Carolingian Archbishop of Lyon, Agobard, Weiss attempts to make a case for the early transmission of this text to Northern Europe by the early 9th century and to show that it was understood within a mythical-mystical framework. Chapter Five is largely a reiteration of Weiss’ 2013 article (Jewish Quarterly Review) that counters Joseph Dan’s popular theory of reception—namely, that readers first understood the Sefer Yeṣirah as a philosophical or scientific treatise until the widespread flourishing of mysticism and magic during the late-12th century. Exploration of the introductory text of the Sefer Yeṣirah in Ms. Vatican 299/4 and the commentary by the Northern European rabbi Shlomo Yitzchaki (a.k.a., Rashi) leads Weiss to conclude, by contrast, that by the 11th century at least, readers acknowledged the mystical and magical qualities of the Sefer Yeṣirah as a contemplative guide, if not practical manual, by which they too might create life with the same building blocks God had.

Sefer Yeṣirah and Its Contexts has much to commend. Weiss’ analysis of the introductory text of Ms. Vatican 299/4 is especially cogent and his overall arguments regarding the context and early mystical/magical reception of the Sefer Yeṣirah are convincing. The relationship between these arguments, though, is not readily apparent and this text might have been better divided into two fuller discussions in separate monographs. As it stands, Weiss’ premises appear rushed, if not problematic. For instance, the limited selection of Western Christian sources cited as an indication of general opposition to letter speculation in the ancient world is too slight to make a statement about dominant versus minority forms of Christianity. Furthermore, such a claim presupposes that the finer points of Christian orthodoxy and orthopraxy had already been hammered out before the 4th century C.E. (which they had not) and that a Western Christian position established the standards for the entirety of the Christian world (which it did not). Weiss’ failure to distinguish between religious ideology and practice in different regions also emerges within his discussion of the Sefer Yeṣirah’s reception: this study does not take into account that the scientific-philosophically inclined commentaries of the Sefer Yeṣirah were composed in the Dar al-Islam while sources indicating an early mystical-magical understanding of the text originated in Western Europe. Weiss’ lack of consideration regarding context is somewhat surprising given his focus in the first half of the text.

Various inconsistencies crop up throughout the text as well, primarily regarding transliteration practices. When discussing a Hebrew term, Weiss seldom provides the Hebrew characters, a transliterated version, and a translation. Instead, sometimes a term written in Hebrew characters without either a transliteration or a translation, or a questionable translation of a transliterated term is included—as is the case with sefirot, which Weiss has translated as “counting,” alluding to numbers, without even mentioning the common kabbalistic meaning of this term as divine emanations; or of nefesh, a term generally associated with the soul or spirit, but which he has translated as “mankind” or the “human body.” Despite these areas for improvement, Weiss’ text is a valuable addition to scholarship on the Sefer Yeṣirah’s contexts of composition and reception.