In the early part of the nineteenth century, one of the great Kabbalists of modern times, Rabbi Isaac of Homel, published a treatise entitled Maamar Ha'shiflut v'Ha'simchah (A Discourse on Humility and Joy) in which he introduced the idea of three distinct stages in the historical revelation of Kabbalah. These three stages, which he refers to as "the three Kabbalot (plural of Kabbalah)," each represent a conceptual approach to understanding Kabbalistic tradition. Each is identified with a particular historical figure whose system of thought served to advance the evolution of Kabbalistic theory by providing new and more illuminating frameworks within which to organize the totality of Kabbalistic doctrine existing up to their time. These three figures, as identified by Rabbi Isaac, were Rabbi Moses Cordevero (1522-1570), also known as the Ramak; Rabbi Yitzchak Luria (1534-1572), popularly referred to as the holy Ari; and Rabbi Yisrael, the Ba'al Shem Tov (1698-1762).
Whereas the revealed law of the Torah realized its greatest revelation at Sinai, only to have its clarity diminish over time, the hidden tradition experienced a virtually opposite situation: its doctrine, whose historical origins are obscure, has come into sharper and sharper focus with every passing generation. This is due to the mediation of select individuals who spontaneously emerged through the course of history, souls whose purpose was to reveal that measure of Divine mystery necessary in order to sustain an existential balance in the world.
The first stage in the revelation of Kabbalistic theory culminated in the 16th century with the work of the great Kabbalist, philosopher and Talmudic scholar, Rabbi Moses Cordevero of Safed. His goal was to rationally systematize all of Kabbalistic thought up to his time, in particular the teachings of the Zohar and its later interpreters. The Zohar, which is the foundational text of Kabbalah, was first publicized in 14th century Spain by Rabbi Moses de Leon, although its teachings originated with the second century Talmudic sage, Rabbi Shimon bar Yochai.
For the thousand years before coming into public view, the teachings of the Zohar were revealed to a select few in every generation deemed worthy of preserving their transmission. For the 250 years subsequent to its publication in 1305, many Kabbalists attempted to provide a conceptual framework within which to understand the loosely associated and highly symbolic homiletics of the Zohar. None were as successful as the Ramak, who in his magnum opus,Pardes Rimonim, demonstrated the underlying unity of Kabbalistic tradition by organizing the various, often contradictory, teachings of the hidden wisdom into a coherent philosophical system. The core of the Ramak's system consists of a detailed description of how finite reality evolved from God's infinite being through a hierarchy of creative forces known as sefirot.
The second stage in the revelation of Kabbalistic theory commenced almost immediately upon the Ramak's demise, and is identified with the work of his successor, Rabbi Yitzchak Luria. Rabbi Luria, otherwise known as the "Ari" (an acronym for "the Godly Rabbi Yitzchak"), was born in Jerusalem but subsequently relocated to Egypt where he quickly established himself as a Talmudic prodigy. Introduced to the secrets of the Kabbalah by one of his mentors, he would often spend extended periods in isolated meditation. During one of his visionary experiences, the Ari was instructed by Elijah the prophet to return to the land of Israel where in the city of Sefad he would find the one destined to become his principal disciple and exponent.
The Ari arrived in Sefad on the very day of the Ramak's funeral. Joining the procession, he discovered that he alone was witness to a pillar of fire following behind the Ramak's bier–a sign, according to the Zohar, that he was meant to inherit the mantle of leadership left behind by the deceased. Nevertheless, the Ari avoided assuming any authority in Sefad for a full half-year until such time as his destined disciple, Rabbi Chaim Vital, presented himself for instruction. The Ari only lived for another two years, but in that short period he managed to reveal a completely new path in the study of Kabbalah. So pivotal were his insights that to this day the study of Kabbalah is virtually synonymous with the study of the Ari's writings.
At the center of the Ari's system is a radically new description of the universe's evolution, focusing on the dynamic interplay of forces within Creation made possible through the elaboration of individual sefirot into complex and interactive partzufim, "personae." Unlike the Ramak's system, wherein the sefirot appear as discrete and autonomous forces advancing the evolution of Creation, the Ari's system posits a universe constantly interacting with itself, engaged in the perennial conflict between good and evil which will only be resolved through the advent of universal redemption–a redemption that man can either hinder or expedite through his own actions.
Subsequent to the Ari, there was one more personality who emerged on the scene, inspiring a qualitative shift in the evolution of Kabbalistic thought. He was Rabbi Israel, the Ba'al Shem Tov (Master of the Good Name). Born in 1698, in the western Ukraine, the Ba'al Shem Tov devoted the first half of his life to wandering among the downtrodden Jews of his region and humbly ministering to their needs. At the same time he was an active member of the nistarim, a secret fraternity of mystics who delved into the mysteries of Kabbalah. In the year 1734, he revealed himself as a Kabbalist and healer, and proceeded to found a popular movement which was to reinvigorate the spiritual lives of Jews all across Eastern Europe. This movement, which came to be known as Chassidism, was firmly based upon the doctrinal foundations of classical Kabbalah; nevertheless it outwardly emphasized the simple and joyful service of God, particularly through prayer and acts of lovingkindness, over the intellectual discipline of Kabbalistic study. It was chiefly the Ba'al Shem Tov's disciples, particularly Rabbi Schneur Zalman of Liadi (1745-1812), who revealed through written elaborations of his teachings their master's profound understanding of Kabbalistic thought. In these works, which form the foundation of Chassidic thought and philosophy, the abstract and often impenetrable formulae of classical Kabbalah are recast into the psychological terms of ordinary human experience. By employing the structure of the soul as an allegorical model for understanding the deepest mysteries of the universe, Chassidism was able to both elevate the consciousness of the ordinary Jew as well as expand the conceptual territory of Kabbalistic reflection.
By including the Ba'al Shem Tov amongst those who advanced the evolution of Kabbalistic thinking, Rabbi Isaac corrects the common misconception of Chassidism as a movement existing outside the formal mainstream of Kabbalah. In fact, according to Rabbi Isaac, not only did the Ba'al Shem Tov influence Kabbalistic thought; he introduced its supreme historical expression, both in terms of conceptual focus as well as its scope of influence upon the lives of the Jewish populace.
It has been said that if Kabbalah is the soul of the Torah, then Chassidism is its "soul within a soul." Rabbi Isaac's identification of three stages in the evolution of Kabbalistic thought implies a necessary sequential process in the exposure of human consciousness to the secrets of Creation. Without first understanding the nature of the Ramak and the Ari's Kabbalistic systems, it is impossible to appreciate the revolutionary turn introduced by the Ba'al Shem Tov.
More information about Kabblah you can read in "What you need to know about Kabbalah"