Sefer Yetzirah (סֵפֶר יְצִירָה Sēp̄er Yəṣīrā, Book of Formation, or Book of Creation) is the title of a book on Jewish mysticism, although some early commentators, such as the Kuzari, treated it as a treatise on mathematical and linguistic theory as opposed to Kabbalah. The word Yetzirah is more literally translated as "Formation"; the word Briah is used for "Creation". The book is traditionally ascribed to the patriarch Abraham, although others attribute its writing to Rabbi Akiva. Modern scholars have not reached consensus on the question of its origins. According to Rabbi Saadia Gaon, the objective of the book's author was to convey in writing how the things of our universe came into existence. Conversely, Judah Halevi asserts that the main objective of the book, with its various examples, is to give to man the means by which he is able to understand the unity and omnipotence of God, which appear multiform on one side and, yet, are uniform.
The famous opening words of the book are as follows:
By thirty-two mysterious paths of wisdom Yah has engraved [all things], [who is] the Lord of hosts, the God of Israel, the living God, the Almighty God, He that is uplifted and exalted, He that Dwells forever, and whose Name is holy; having created His world by three [derivatives] of [the Hebrew root-word] sefar : namely, sefer (a book), sefor (a count) and sippur (a story), along with ten calibrations of empty space, twenty-two letters [of the Hebrew alphabet], [of which] three are principal [letters] (i.e. ), seven are double-sounding [consonants] (i.e. ) and twelve are ordinary [letters] (i.e. ).
A cryptic story in the Babylonian Talmud states,
On the eve of every Shabbat, Rav Hanina and Rav Hoshaiah would sit and engage in study of Sefer Yetzirah, and create a delicious calf and eat it.
Mystics assert that the biblical patriarch Abraham used the same method to create the calf prepared for the three angels who foretold Sarah's pregnancy in the biblical account at Genesis 18:7.