 His writings, including studies of Hasidic masters, and Neo-Hasidism, saw Hasidism as the classic expression of Aggadic tradition.Heschel held the Aggadah's theology, poetic exegesis and spirituality to be central to the meaning and history of Judaism.In literature, Hasidic spirituality influenced among others Elie Wiesel, Shmuel Yosef Agnon and Yiddish writers.