Sefer HaZohar ("The Book of Splendor") is the central and perhaps greatest work of Kabbalah. By ancient tradition it is counted as part of the esoteric Torah Sh'Bal Peh ("Oral Torah") given to Moses at the same time as the Written Torah, or "Old Testament," and revered by the Jewish Sages throughout history as equal to it in authority. To all who study it with good intention the Zohar is clearly the divinely transmitted work of the Bat HaKol ("Voice of the All") that speaks through its God-inspired teachers in every generation.
"All of us have been studying the Zohar together in these classes for over six years now -- volume by volume, section by section, page by page, paragraph by paragraph, sentence by sentence, word by word and ever letter by letter. In all that time, what we see is that the Zohar has nothing to do with religion. It has everything to do with God. It has everything to do with man's Avodah, man's service, which is to return God to His wholeness, that completeness from which He has fallen
[through the act of Creation]." (Reb Yakov Leib HaKohain, Zohar Shiur, 12-20-04)