There’s an old proverb popularized by Mel Brooks that sums up “Fractured Continent,” William Drozdiak’s fine, eminently readable analysis of European politics that made The New York Times Most Notable 100 Books list for 2017. The proverb is: “Hope for the best, expect the worst.” But even if the “crises” explored by Drozdiak in 14 Western capitals, don’t constitute the worst in the continent’s 70-year-old attempt to achieve unity after World War II, they do exemplify a deepening division within