Book excerpt: During the German “Kulturkampf” in the 1870s, the Frankfurt rabbi Samson Raphael Hirsch enjoined all Jews of his community to exercise a right given by Prussian law: to withdraw from the united community which was dominated by Reform forces in order to belong only to a separate Orthodox community, founded according to Jewish law (Halakha). This work investigates the significance of these events for Orthodox Judaism in the 20th century. Focussing on the philosophy of Isaac Breuer, the grandson of Hirsch, Frankfurt attorney, novelist and co-founder of the Orthodox world movement Agudat Israel, this book describes the dilemmas of observant Jewry vis-à-vis the secularist Zionist movement. It shows the genesis modern Jewish Orthodoxy and helps to understand its activities, in a new “Kulturkampf”, in the state of Israel until today.