Martin Buber's life's work was dedicated to an understanding of orthodox and ultra-ortodox mystical Jewish movements in the West. A further major achievement was the translation of the Hebrew Bible into German, undertaken with the philosopher Franz Rosenzweig. His works of religious philosophy (e.g. I and Thou, 1923) posit dialogue as the foundation of human relationships as well as man's relationship with God. Buber was also an early participant in the Zionist movement.
Martin Buber (1878–1965), black-and-white photograph, date and location unknown, photograph: Tita Binz; source: © Deutsches Historisches Museum, Berlin, Inv.-Nr.: Ph 95/242, http://www.dhm.de/lemo/bestand/objekt/ph006624.