The Kabbalah is the innermost aspect of Judaism. You can call it “the soul of Judaism” and it corresponds to our own soul. it is called the “hidden wisdom” becauseit deals with our intentions towards ourselves , each other and God. Our actions can be seen for the outside , but only we really know what we mean by them
It is only through learning the Kabbalah that we can know who we are and what our real purpose in our life is. Rabbi Chaim Vital z’l likened someone who keeps the Torah and mitzvot without learning the Kabbalah, to a body who sits in darkness. (Introduction to the Ten Sephirot, Rabbi Ashlag)
Yes, Rabbi Ashlag addresses this issue in his work the “Introduction to the Study of the Ten Sephirot”. There are two parts of the Kabbalah. One part is called the “Secrets of the Torah” and these is not written down but passed on only from Rabbi to pupil when the disciple is ready. The other part is called the “Reasons for the Torah” and this part is written down and is available for all to learn. Regarding any printed material, including the Zohar itself, which has been composed by a great Kabbalist you may be quite certain does not contain any thing that is forbidden for anyone to learn. A different aspect of Kabbalah which is certainly forbidden is the misuse of Kabbalah to achieve personal aims. This includes everything that may be labeled “practical Kabbalah”. for example, using the Names of God, segulot of all types, superstitions, and so forth to gain something
Everything depends on our motive. Rabbi Ashlag and the Rav Abraham Isaac Kook, the first Chief Rabbi of (then) Palestine both not only allowed the learning of Kabbalah but encouraged it for all , providing there is a genuine desire to learn it for its own sake. If a person wants to learn Kabbalah because he has completed his studies in the other parts of the Torah , and he wants to add the dimension of the Kabbalah as part of his studies, then he should wait until he is married and over the age of forty. There are now classes for women in the Kabbalah and being a woman is no longer the barrier it once was.