The primary texts of Kabbalah were once part of an ongoing oral tradition. The written texts are obscure and difficult for readers who are unfamiliar with Jewish spirituality which assumes extensive knowledge of the Tanakh (Hebrew Bible), Midrash (Jewish hermeneutic tradition) and Halakha (practical Jewish law).
For kabbalists, ten utterances in Genesis with which God created the world are linked to the ten sefirot—the divine structure of all being. According to the Zohar and the Sefer ha-Yihud, the Torah is synonymous with God. More specifically, in the Sefer ha-Yihud, the letters in the Torah are the forms of God. The kabbalist looks beyond the literal aspects of the text, to find the hidden mystical meaning. The text not only offers traditions and ways of thinking, but it also reveals the reality of God. One of the first Jewish philosophers, Philo of Alexandria (20BCE-40), said that Abraham knew the essential Torah, before it was given, because Abraham was himself a philosopher: he observed the world around him and looked inside himself to discover the laws of nature. While this is not strictly speaking a mystical notion, it does introduce the idea of an inner Torah that underlies the written word. Much later, in the 19th century, the Sfas Emes, a Hasidic rebbe, made the assertion that it was actually Abraham’s deeds that became Torah. The Torah is thus seen as an ongoing story played out through the lives of the Nation of Israel. The Torah is an important text because even the most minor traditions of the Kabbalah will acknowledge its aspects of the divine.
Jewish forms of esotericism existed over 2,000 years ago. Ben Sira warns against it, saying: "You shall have no business with secret things". Nonetheless, mystical studies were undertaken and resulted in mystical literature. The first to appear within Judaism was the Apocalyptic literature of the second and first pre-Christian centuries and which contained elements that carried over to later Kabbalah. According to Josephus, such writings were in the possession of the Essenes and were jealously guarded by them against disclosure, for which they claimed a certain antiquity (see Philo, De Vita Contemplativa, iii., and Hippolytus, Refutation of all Heresies, ix. 27).