R. Yaakov Yosef of Polnoye

Rabbi Yaakov Yosef HaKohen Katz of Polnoye (c. 1710–1784) was the closest disciple of the Baal Shem Tov and the first Hasidic master to publish a book — an event that, more than any other, transformed Hasidism from a movement of oral charismatic teaching into an enduring literary tradition. Born in Sharigrad and originally a fierce mitnaged, he met the Besht in Mohyliv around 1741 and underwent a transformative spiritual reorientation. He served as rabbi in Sharigrad, Rashkov, Nemirov, and (from 1748) in Polnoye.

His *Toldot Yaakov Yosef* (1780), printed at his own expense in Korzec, ignited the polemical controversy with the Vilna Gaon by openly attributing teachings to 'I have heard from my teacher' (the Besht). It remains the single most important literary source for the Besht's own teachings, along with his later *Ben Porat Yosef*, *Tzofnat Pa'aneach*, and *Ketonet Passim*.