The eighty-four years of Zalman Shazer, the third president of the State of Israel (1889-1974), encompass the great drama of Jewish life from the end of the nineteenth century to the second half of the twentieth century: the growth of the national and cultural movement in Eastern Europe and the Jewish settlement in the Land of Israel, and the establishment of the state and the struggle for its security and beauty. Along Shazer's journey he encountered famous figures such as Berel Katznelson, David Ben-Gurion, the Lubavitcher Rebbe, and his three great loves: Rachel Katznelson, Rachel the poet and Golda Meir. Who was this man? A Hasid who disguised himself as a secularist or a secularist who became a Chabad Hasid? A romantic who met a beautiful goose herder and did not forget her for the rest of his life or a husband who distanced himself from his wife and loved to stay away from home? A deep researcher of the Sabbatarian movement or a politician? Since the founding of the state until the end of his life, Shazar acted as a public figure in the State of Israel, and at the end of his public career he became its number one citizen, its third president. The biography In Two Worlds unfolds the story of his life and discusses the internal tensions and his struggles - between religion and tradition and secularism, between politics and research, between the Diaspora and the Land of Israel, and between the women he loved. Together, these created a unique and fascinating character.