R. Israel Ben Eliezer Ba'al Shem Tov (Besht; c. 1700–1760) was the charismatic founder and first leader of Hasidism in Eastern Europe. He became Hasidism's first teacher and its exemplary saint. It is related that Besht was born in Okop, a small town in Podolia, to poor and elderly parents in hard times aggravated by wars in the region. Orphaned as a child, he later eked out a living first as an assistant (behelfer) in a heder and later as a watchman at a synagogue. At Yazlovets, near Buchnach, where he was working as behelfer, he met and became friendly with young Meir b. Zevi Hirsch Margolioth, later a famous talmudic scholar; Israel was considered by Meir both as colleague and teacher. According to tradition, in his 20s Israel went into hiding in the Carpathian Mountains in preparation for his future tasks. (He was accompanied by his second wife, Hannah, the first having died shortly after their marriage.) There he lived for several years, first as a digger of clay, which his wife sold in town; later he helped his wife in keeping an inn. In about 1730 he settled in Tluste. Besht had one son, Zevi, and a daughter, Adel. His grandchildren were R. Moses Hayyim Ephraim of Sudylkow and R. Baruch of Medzibezh; R. Nahman of Bratslav was his great-grandson. In the mid-1730s - hasidic tradition fixes it on his 36th birthday - Besht revealed himself as a healer and leader. The circles of his followers and admirers widened rapidly. Many people were drawn by his magnetism and the widespread reports of his miracles, and several groups of Hasidim which had been formed earlier came under his influence and accepted his leadership and teaching to a greater or lesser degree, among them R. Abraham Gershon of Kutow, Besht’s brother-in-law; R. Aryeh Leib of Polonnoye; R. Nahman of Kosov; and R. Nahman of Horodenka (Gorodenka)). Tradition hints that some of the members of these hasidic circles were at first repelled by Besht’s activity as miracle healer, as a ba'al shem, although Besht himself was proud of this work, as demonstrated by his signature "Israel Ba'al Shem of Tlust" (Responsa Mayim Hayyim part one, 1858). However, contemporaries who did not belong to his circle regarded this activity favorably, as indicated by the designation of Israel as "the famous ba'al shem tov, may his light shine" (Meir Teomim in Nofet Zufim Rav Peninim, 1772).

Besth undertook journeys (Shivhei ha-Besht tells a great deal about his travels and horses) to effect cures, expel demons and evil spirits (lezim), and to win influence. In eulogistic folktales, the tradition of his pupils, and in writings hostile to him (see David of Makow), the interdependence of his healing work and the charisma of his leadership are clearly apparent. Later hasidic tradition, however, tried to deprecate the importance of these healing and magical practices. In tales about him as well as through his teachings, Israel's great personal charm, remarkable magnetism, and ecstatic personality and behavior are revealed. Prayer was his main ecstatic and mystic approach to God, but intellectual study and learning took a secondary place. In specially exciting moments he reached a state of mystical exaltation - aliyyat neshamah - of which he gave realistic descriptions. Future events and past personalities, both good and evil, were shown to him in dreams. In traditional tales he is portrayed as engaged in conversation and in meeting with people, even women, individually or in small groups. He is never described as preaching in a synagogue. The traditional picture of Israel, always with his pipe in his hand or mouth, emphasizes the importance of his edifying secular tales. Israel's teachings do not indicate any talmudic scholarship, and his opponents criticized him for the lack of this and for his preoccupation with healing, writing amulets, and his conversation with simple men (see, e.g., David of Makow in PAAJR, 25 (1956), p. 147). Material from the aggadah and moralistic and kabbalistic works and traces of an acquaintance with the writings of Saadiah Gaon are evident in his teachings. Besht and his followers were conscious of his mission as a leader of his people. Many of his dreams and visions, much of what was revealed to him from on high, are related to the actual problems and sufferings of the Jews in his generation. Teaching the importance of charity, he himself gave much, and he helped in ransoming captives and prisoners, a pressing problem in his time. He taught that devotional joy was the proper attitude of the Jew in every moment of his life and in particular in prayer, exemplifying this through his own attitude to life and through his own mode of prayer. His admirers told especially about the light and fire that they imagined emanating from his person, and about his fiery way of reciting his prayers. Opposing too much fasting, he advised against preaching through harsh admonition. Even more than his teachings, his idealized personality became the inspiration for the life, leadership, and aspirations of the Hasidim up to the present day. It is typical of hasidic appreciation of the personality of its ideal figure that tales related by R. Jacob Joseph of Polonnoye state that Israel's particular teacher in heaven was Ahijah the Shilonite, the prophet of the overthrow of a misguided establishment and of a new kingdom in Israel. Whether partly true or wholly legendary, the hasidic tale that in his youth Besht miraculously came by "compositions containing secrets and mysteries of the Torah, divine and practical Kabbalah" which had belonged to Adam Ba'al Shem expresses the awareness that the theoretical roots of Israel's teachings lay in the Kabbalah; the story also indicates the hasidic conviction that his appearance and influence was a mystery and a miracle.