For two centuries, Elijah Ben Solomon of Vilna, Lithuania has been known simply by the name “Gaon” or genius. His biographers claim that “one like him appears every thousand years.” Born into a respected rabbinic family, Elijah from early adolescence distinguished himself by his mastery of rabbinic literature, mathematics, and scientific knowledge. Fiercely reclusive, he held no public position and spoke out only on the most pressing political matters. Still, he would become the patron sage and spiritual leader of eastern European Jewish life. Elijah’s contributions as author, leader, and genius laid the groundwork for the central institutions and ideologies of modern eastern European Jewry. By the time of his death in 1797, he had written commentaries on a wider range of Jewish literature than any writer in history. This biography of the Vilna Gaon places this towering figure in the context of his times and provides an analysis of his importance in the development of modern Judaism.