When we meet a new person, we first only see their exterior, while their inner world is revealed to us only gradually, over time. So too Kabbalah was not revealed all at once. Throughout most of history, the study of Kabbalah was prohibited from most people and was reserved for exceptional scholars and mystics. A well-known principle, for example, prohibited studying Kabbalah before the age of 40, and although many great Kabbalists did not adhere to this prohibition (three of the most prominent among them—the Holy Rabbi Isaac Luria, Rabbi Moshe Chaim Luzzatto, and Rabbi Nachman of Breslov—all died before reaching the age of 40), others certainly did. And everybody was very careful about not revealing Kabbalah to the masses.
Two main concerns stood behind this caution. The first was that someone might misuse practical Kabbalah for evil purposes, and the second, that the metaphors and imagery used by Kabbalah—which attribute “forces”, “organs”, and more to the Divine—would not be properly understood and would lead to anthropomorphic and heretical conceptions of God. These concerns were not unjustified, and there were enough cases that showed that, in the wrong hands, Kabbalah could indeed be used as a tool to distort the Torah. The most notorious case is that of Shabtai Zvi, the 17th century false messiah who led many astray.
The first person to change this perception was the Rabbi Isaac Luria Ashkenazi, the Holy Ari, the greatest mystic of the modern era, who taught in Safed in the late 16th century (and whose grave there can be visited to this day). Beyond his significant innovations that made Kabbalah into a detailed and systematic topic of study, the Holy Ari made two important changes regarding the revelation of Kabbalah: one, he almost completely prohibited the use of practical Kabbalah; and two, he explained that in our time, “it is permitted and good to reveal this wisdom,” i.e., Kabbalah.
The Ari did not mean that Kabbalah should be taught to everyone, but only to those who are worthy of it (who are very refined in their character traits, who have studied much of the revealed Torah, and who have met other criteria). Yet this was a significant expansion of the circle of those exposed to Kabbalah. The Ari also believed that the study of Kabbalah would bring the world closer to the state of redemption, in which everyone would be whole in body and soul.
