The Zohar is a type Jewish literature which pretends to be a revelation from God communicated through R. Simeon ben Yohai to the latter's select disciples. Under the form of a commentary on the Pentateuch, written partly in Aramaic and partly in Hebrew, it contains a complete cabalistic theosophy, treating of the nature of God, the cosmogony and cosmology of the universe, the soul, sin, redemption, good, evil, etc. It first appeared in Spain in the thirteenth century.(1)
Background On Rabbi Shimon:
To fill the spiritual vacuum left by the death of his students, the great Rabbi Akiva chose a select five men to whom to pass over the secrets of the Torah. Rabbi Shimon Bar Yochai stood out amongst them and eventually wrote the secrets of the Torah – the Kabbalah – in his work, the holy Zohar.(2)
1). Jewish Encyclopedia ( http://www.jewishencyclopedia.com/view.jsp?artid=142&letter=Z)
2). Arutz 7 (5-16-2006)