This work is the first study in any language of the thought and writings of Rabbi Zadok HaKohen of Lublin (1823-1900), who created a blend of ecstatic Hasidism and intellectual Talmud study. With extensive citations of his writings, it will be an entry point to his thought for many American readers. To illuminate R. Zadok's innovative spiritual path, in which one attains mystical experience through intellectual study of Torah, Brill explores the realm of spiritual psychology with particular attention to individual growth, sin, determinism, and pluralism. He shows that R. Zadok's thought combined mystical, Aristotelian, and psychological elements. This work also sheds important light on Lithuanian talmudic intellectualism and Polish Hasidism. It is the first book to present a critical, analytical portrait of hasidic theology. Particular attention is paid to R. Zadok's teacher, Rabbi Mordekhai Leiner of Izbica, whose individualistic philosophy undergirds R. Zadok's teachings on the subject of free will. Finally, this superb study addresses the question of how a Jewish thinker in a traditional milieu was able to derive a theology with many elements we would consider modern, even though he was largely insulated from and, in theory, opposed to contemporary Western, non-religious thinkers. Published in association with Yeshiva University Press