Historian and author Frederic Morton. Morton's new book is "Thunder at Twilight: Vienna 1913/1914." In it, Morton examines that city on the eve of the First World War. Book critic John Leonard described the mix of intellectualism, arts, and political intrigue going on in Vienna at that time as "waltzing on the edge of the abyss." Morton's previous book, "A Nervous Splendor," looked at Vienna in 1888 and '89.