Jewish mysticism differs radically from all other mystic schools.
The Kabbala is always and exclusively within the context of Torah. As a body cannot function without a soul, so the soul is ineffective without the body. The soul of the Torah ('nistar,' the esoteric part of the Torah) can never be separated from the body of the Torah ('nigleh', the exoteric parts; halacha, the commandments and practices prescribed by the Torah). Kabbala reduced to spiritual or philosophical symbolism, stripped from the observance of the mitzvot, is worthless mumbo-jumbo, an empty shell.
This is the first and foremost difference between Jewish mysticism and all other kinds and forms. That is why Jewish mysticism can never fall into the category of a cult.
The great mystics and philosophers outside Judaism, in the East and in the West, were honest and sincere sages. They did seek truth. They did not look for answers to justify or verify any of their preconceived notions. They were not indulging their egos. And many did discover and develop profound theories and insights which stir the imagination and move the human spirit. Some had glimpses of ultimate reality. Yet, in spite of all this, they worked in a chameleonic void. They could move only as far as finite and fallible man is able to reach on his own. Their insights or findings, therefore, are either humanly verifiable (that is, logically self-evident truth or tautologies) or else speculative truth which at best contains an element of possibility but never the assurance of certitude.
The Kabbala, on the other hand, builds on the revealed truth of Torah. The validity of its speculative theories and subjective experiences must be, and is, tested and verified by that truth in order to be worthy of consideration, to be viable and acceptable. It has, and continually uses, objective criteria to make it consistent with, and as reliable as, halacha.
At this point, though, we must realize that Jewish mysticism - the Kabbala and Chassidism - is not just a legitimate and respectable part and dimension of authentic Judaism, of Torah.
The Torah is an organism, a complete whole in which every part is most intimately interrelated and interwoven with every other part; in which everything is interdependent upon everything else. The Torah is an organism analogous and parallel to, and in complete interaction with, the organism of the universe in general and the organism of man in particular. No part or particle, therefore, can be taken in isolation from the others.
Thus, even as it is incumbent upon each and every one of us to pursue the study and practice of the "body" of the Torah - halacha; mitzvot - so it is obligatory and essential for each and every one of us to pursue the study and inspiration of the "soul" and fruits of the Torah and its interpretation.
To be sure, each of us is limited by his or her natural capacities. No one can absorb the totality of the Torah in its divine infinity. But everyone can and must actualize his or her own potential, can and must reach out as far as his or her abilities can take them.
In fact, nowadays more than ever before, there is a most urgent need for the illumination and inspiration of the mystical dimension of the Torah. This very need is the great vision and contribution of the Baal Shem Tov and Chassidism.
This is what it is all about, and the rest is but commentary. So now let us go forth and study - "to comprehend and to discern, to perceive, to learn and to teach, to observe, to practice and to fulfill all the teachings of G-d's Torah with love."
[from "The Mystical Dimension" Vol. I by Rabbi Jacob Immanuel Schochet]