A volume of the work known as the Zohar (Splendour) which is the key text of the Kabbalah. The Zohar is a commentary on the Torah and although it is sometimes ascribed to a 2nd-century rabbi from Simon Bar-Yochai, the form in which it is most widely known originates with Moses of Leon, a native of Grenada, who died in 1305. The kabbalists believe that the undefinable origin of all things is Ein Sof - the causes of causes, the infinite, that which underlies everything. The universe emanates from the divine in successive layers called sefirot. Everything exists in God but God extends infinitely beyond existence. According to The Book of Concealed Mystery, the light of God must be concealed in order to be revealed to creation. Even though the kabbalists believe that ultimately Ein Sof is beyond expression or understanding, the contemplation of God's presence in all things causes our thoughts to be purified.