The Sefer Yetzirah ("Book of Formation") is a very short, dense and enigmatic Hebrew cosmological treatise, only some 1,600 to 2,500 words depending on the recension, describing how God created the universe through "thirty-two paths of wisdom": the ten sefirot and the twenty-two letters of the Hebrew alphabet, mapped onto numbers, planets, months and parts of the body. Its authorship and date are genuinely uncertain and much argued.
Tradition ascribes it variously to the patriarch Abraham or to Rabbi Akiva, but these are legendary attributions; scholars place its composition anywhere from the second to the sixth century CE, in a milieu touching both rabbinic Judaism and late-antique Neoplatonism and Neopythagoreanism, and it circulates in several distinct recensions (a short version, a long version, and the one embedded in the tenth-century commentary of Saadia Gaon). It predates the developed Kabbalah by centuries and is not itself a Kabbalistic work in the medieval sense, but it supplied the later tradition with the word sefirot and with the idea of creation through letter and number, and drew a long line of commentators. The golem legends, in which a man is animated by combinations of the Hebrew letters, descend from its account of the creative power of the alphabet.