It was Israel Joshua, a forceful and bold personality, who had been the trailblazer, preparing the way for the more passive and self-conscious Isaac. It was Israel Joshua who first broke with, more irrevocably than his brother, the Orthodox insularity of the family—from their father, mystical and impractical, a rabbi from a Hasidic line, and their mother, the daughter of a non-Hasidic rabbi and the so-called “rationalist” of the couple. (Via TNR)