The founder of modern Hasidism was the Polish-born Israel ben Eliezer (ca. 1700-ca. 1760), who is generally known as Baal Shem Tov (Good Master of the Name).
Israel ben Eliezer was born to aged parents in Okopy, a small town in the Ukraine. He was apprenticed to the local teacher and was later employed as an aid to the sexton of the synagogue, where he spent his nights studying the Cabala, or Jewish mystic lore.
Israel married at the traditional age of 18, but his wife died shortly afterward. He then moved to Brody in Galicia, where he met and married the rabbi's sister. They moved to a distant village in the Carpathians. There Israel worked as a laborer, but he managed to devote considerable time to prayer and contemplation in the forest. He learned the use of medicinal herbs for the treatment of disease, and he became a Baal Shem, a master of the occult art of manipulating the name of the Ineffable and his ministering angels as a means of exorcising demons, driving out ghosts, and avoiding other evils. He ministered to his rural neighbors, both Christians and Jews, and performed miraculous cures of both body and soul. He is said to have undergone an Hitgalut (self-revelation) at the age of 36, through the mediacy of a divine spirit.
About 1740 the Besht (the common abbreviation of Baal Shem Tov) settled in Miedzyboz, Podolia. His kindliness and sanctity attracted many followers, who were called Hasidim (the pious). The Besht's teachings emphasized the love of God and trust in Him. God is everywhere and there is no place free of Him. The Besht taught that devoted and fervent prayer was a channel through which divine light flows to man and leads his soul to God. Gloom and sadness were anathemas to the Besht; one of his principles was, "Serve the Lord with gladness." To aid men in their religious life, he introduced a new functionary into Judaism—the Tzaddik (the righteous), who has a highly developed awareness of the divine. The Tzaddik has become the hereditary leader of the Besht's followers.
The Besht used anecdotes and parables to illustrate his teachings. He wrote no works, but after his death compilations of his sayings and teachings were published. Hasidism had, and continues to have, a notable impact on Jewish life.
Further Reading on Baal Shem Tov
Rosman, Murray Jay., Founder of Hasidism: a quest for the historical Baal Shem Tov, Berkeley, Calif: University of California Press, 1996.
Heschel, Abraham Joshua, A passion for truth, Woodstock, Vt.: Jewish Lights Pub., 1995.