The Zohar, meaning splendor, was the first written work containing very much Kabbalistic information. Such information is esoteric doctrines contained in Hebrew Scriptures, but cannot be perceived by the uninitiated; they are, however, plainly revealed to person of spiritual mind. No other information about Kabbalism was recorded before this work.
The knowledge in the Kabbalah had been taught orally and transferred from Moses. Before this it had been thought to initially have been taught by God Himself to a select company of angels. After the Fall the angels most graciously communicated the heavenly doctrine to the disobedient child on earth, to furnish the protoplasts with the means of returning to their nobility and felicity.
From Adam it passed to Noah and then to Abraham, who immigrated to Egypt where he allowed some of the mysterious doctrine to leak out. It was in Egypt, the land of his birth, that Moses was first initiated into the Kabbalah.
Moses learned this mysterious teaching while learning all the wisdom of Egypt; however, he became most proficient in it during his wonderings in the wilderness, when he devoted to it not only his leisure hours of the forty years, but received lessons in it from one of the angels. With the aid of this mysterious science the lawgiver was enabled to solve the difficulties that arose during his stewardship of the Israelites, in spite of the pilgrimage wars and frequent miseries of the nation. He covertly laid down the principles of this secret doctrine in the first four books of the Pentateuch, but withheld them from Deuteronomy.
Moses also initiated seventy Elders into the doctrine’s secrets, and they in turn initiated others. Of all who formed the unbroken line of tradition, David and Solomon were the most deeply initiated in the Kabbalah. No one, however, dared to write it down till Schimeon ben Jochai, who lived during the time of the destruction of the second. After his death, his son, Rabbi Elaezar, and his secretary, Rabbi Abba, as well as his disciples, collated Rabbi Schimeon ben Jochai’s treatises, and from them composed the celebrated work called Z H R, Zohar, or splendor. A.G.H.
Spence, Lewis, An Encyclopedia of Occultism, New York, Carol Publishing Group Edition, 1996, p. 241