From Inner.org, the writings of Rabbi Ginsburgh (hassidic kabbalist in Israel), from his weekly mailing list (available to all, click here):
"In general there are 5 stages in the revelation of the wisdom of Kabbalah, each stage appearing (one might say, even encoded) within a particular text."
One: The Book of Formation
The text revealing the first stage that corresponds to the vital level of the soul is The Book of Formation (Sefer Yetzirah). According to Jewish tradition, the wisdom in this text is attributed to the first Jew, Abraham. In length, it is a relatively short text, and most of its content appears in enigmatic phrases, and it appears clear from its language that it indeed has very ancient roots. Explicitly, this means that the wisdom contained in The Book of Formation antedates the giving of the Torah at Mt. Sinai . Nonetheless, traditionally, the final edition of the book as we have it before us, was compiled in the generation before the destruction of the Second Temple (1 st century CE) by the greatest sage of the Tannaic (Mishnah) period, Rabbi Akiva. Rabbi Akiva was also the master and teacher of Rabbi Shimon bar Yochai, the author of the Zohar, literally The Book of Brilliance.
BS"D - בסיעתא דשמיא