Rabbi Israel Baal Shem Tov (1698-1760) was the founder of Hasidism, a Kabbalistically-oriented revival movement which eventually swept through Eastern Europe and is still widespread today. Like the founders of many movements and religions, we possess very little that the Baal Shem Tov himself wrote, and most of our knowledge of him is based on books published after his death. Some of those sources appear to be reliable biography; others are hagiography, filled with miraculous accounts of the Baal Shem Tov's life and works.
Charismatic, insightful, and apparently gifted both in mystical practice in and relating to everyday people, the Baal Shem Tov was one of many "holy men" circulating in Eastern Europe in the late eighteenth century -- but the only one to found a sect that, within 50 years of his death, had spread throughout the entire region. He was a man, in many ways, of contradictions. His teachings were at first confined to a small elite, but quickly became a mass movement. The essence of his teachings was simple -- there is nothing but God, and our task is to live in devekut, cleaving to God -- but their roots were in the complicated Kabbalah of the Ari, and in response to the heresies of Sabbateanism. And the Baal Shem Tov himself was a man who seemed to many to be an unschooled peasant, but who was actually much more learned than he appeared.
The early life of the Baal Shem Tov (or "BeShT," the acronym by which he his sometimes known) is shrouded in mystery and legend. He was born in a small town near the Polish-Russian border, in the region known as Podolia. It is told in the legendary accounts of his life that the young Israel would wander in the fields and the forests, in close communion with the Divine; whatever the truth of these accounts, certainly a heartful, soulful emotional relationship with God would become a central feature in the Besht's Hasidism. Indeed, perhaps the best summary of Hasidism and how it relates to Kabbalah is contained in the Hasidic teaching that "The Kabbalists of old had all the keys to all the locks in heaven. We don't, so we use our prayer to break down the door."
Eventually, the Besht became a simple teacher of schoolchildren in the town of Brody, probably becoming acquainted with the students in the kloiz, or advanced yeshiva (really, a bit like a monastery), there. It was not until 1734 that he revealed himself as a spiritual master, and took on the name Baal Shem Tov. The name itself is instructive. A Baal Shem is, essentially, a miracle worker who would use angelic or Divine names for healing or magic; there are many baalei shem whose existence is recorded in history. The name Baal Shem Tov is a bit audacious, since it implies that the Besht could use "The" Divine name as well. As has been shown by scholars, the seemingly simple and pietistic of Hasidism -- ecstatic prayer, emotional love of God and people, spirituality being more important than scholarship -- have behind them an intricate structure based on Kabbalistic ecstasy, theury, and magic.
One of the few writings that is almost certainly by the Besht himself is a letter to his brother in law, in which he describes an ascent to the heavenly realms -- now known as the Iggeret Hakodesh and reproduced here on this site. The Baal Shem Tov there meets the Messiah, and immediately asks him when he will arrive on Earth. The Messiah answers, "when your teachings become publicized and revealed to the world, and your well-springs have overflowed to the outside ... so that others, too, will be able to perform mystical unifications and ascents of the soul like you." The Baal Shem Tov reports being greatly troubled by this answer, since " a long time must pass for this to be possible." Yet this text does say a great deal about Hasidism's emphasis on promoting once-hidden teachings. In former centuries, Kabbalists regarded their wisdom as secret, and reserved it only for the few. Especially after the Sabbatean heresy, mainstream authorities likewise forbade the study of Kabbalah by all but the elites. But, inspired by this teaching of the Baal Shem Tov, most Hasidim, in the movement's first hundred years at least, spread Kabbalistic teachings throughout the masses.
Eventually, later Hasidim would close the doors again, claiming that the ordinary people of their generations were not as worthy as those of the Besht's. But in the last fifty years, the portals are open once more, in the guise of 'neo-Hasidism,' the outreach efforts of Chabad, and Kabbalistic institutions like this very website. To be sure, unlike some of the latter-day popularizers of Kabbalah, the Besht insisted on maintaining a life of mitzvot, and, while he did simplify Kabbalah, never "dumbed it down." He left behind several prominent students, and leadership of the Hasidic sect eventually passed to Rabbi DovBer of Mezrich, who coordinated the explosive growth of the movement and set up Hasidic courts in cities across Eastern Europe. Within a single generation, the conditions set down in the Baal Shem Tov's vision seemed far closer to fulfillment.