Book excerpt: "After decades of research, a noted Israeli genealogist has produced a book about the Vilna Gaon that contains a rare portrait of the illustrious 18th-century Eastern European sage, a discussion of his substantial influence on the Jewish world and a thoroughly-documented family tree listing more than 20,000 descendants of the rabbi and his siblings ... Besides exploring the life and times of the Vilna Gaon, the 704-page book identifies, provides documentation for more than 20,000 descendants of the Vilna Gaon and his siblings. There is an index listing all persons in the book. The Gaon's descendants seem as diverse as the Jewish people itself, Freedman said. Some descendants were prominent rabbis and academicians. Some were involved in a rare agricultural settlement experiment in Russia, while others variously served in the American Civil War and emigrated to places like England and Australia well before the mass migrations of the 1880s.