On August 10, 1938, Lucy S. Dawidowicz set sail from New York to Vilna, Poland, to study at the Yiddish Scientific Institute (YIVO). For a year, while she studied the Jewish past, she immersed herself in Vilna's present, getting to know the Jewish rich and poor, witnessing Poland's brutal anti-Semitism. Then she was forced to flee Vilna, just a week before German tanks and troops rumbled into Poland and eventually destroyed this citadel of East European...