Kabbalah. A Very Short Introduction Joseph Dan Oxford University Press, USA
Our libraries contain many hundreds of works of kabbalah, printed or still in manuscript form. And, beside these, there are thousands of works—collections of sermons, ethical treatises, and commentaries on the scriptures and the Talmud—that use a little or more kabbalistic terminologies and ideas.
As a result, there is hardly a Jewish idea that cannot be described as “kabbalistic” with some justification, as most of these ideas are found in works that use kabbalistic terminology.
How can one distinguish between a traditional Jewish ethical norm and a kabbalistic one? Today, it often seems that designating an idea as “kabbalistic” makes it more welcome to outsiders than if it were described as “Jewish.” The main work of the medieval kabbalah, the book Zohar, contains 1,400 pages that deal with every conceivable subject. There is nothing that cannot be confirmed by a quotation from the Zohar.