The Zohar (Hebrew: זֹהַר, lit. "Splendor" or "Radiance") is the foundational work in the literature of Jewish mystical thought known as Kabbalah. It is a group of books including commentary on the mystical aspects of the Torah (the five books of Moses) and scriptural interpretations as well as material on mysticism, mythical cosmogony, and mystical psychology. The Zohar contains discussions of the nature of God, the origin and structure of the universe, the nature of souls, redemption, the relationship of Ego to Darkness and "true self" to "The Light of God". Its scriptural exegesis can be considered an esoteric form of the Rabbinic literature known as Midrash, which elaborates on the Torah.
The Zohar is mostly written in what has been described as a cryptic, obscure style of Aramaic. Aramaic, the day-to-day language of Israel in the Second Temple period (539 BCE – 70 CE), was the original language of large sections of the biblical books of Daniel and Ezra, and is the main language of the Talmud. However in the late middle ages the language was used among Jews exclusively in the study of such earlier texts. The Aramaic of the Zohar is not very sophisticated and appears to be written by someone who did not know Aramaic as a native language. Moreover, vocabulary from medieval Spanish and Portuguese is prevalent in the language of the Zohar.
The Zohar first appeared in Spain in the 13th century, and was published by a Jewish writer named Moses de León. De León ascribed the work to Shimon bar Yochai ("Rashbi"), a rabbi of the 2nd century during the Roman persecution who, according to Jewish legend, hid in a cave for thirteen years studying the Torah and was inspired by the Prophet Elijah to write the Zohar. This accords with the traditional claim by adherents that Kabbalah is the concealed part of the Oral Torah.
In the Bible, the word "Zohar" appears in the vision of Ezekiel 8:2 and is usually translated as meaning radiance or light. It appears again in Daniel 12:3, "Those who are wise will shine like the brightness of the heavens".