JERUSALEM — Two photographs adorn the office of Prime Minister Benjamin Netanyahu. Together they illuminate a portentous fact: No two leaders of democracies are less alike — in life experiences, temperaments and political philosophies — than Netanyahu, the former commando and fierce nationalist, and Barack Obama, the former professor and post-nationalist. One photograph is of Theodor Herzl, born 150 years ago. Dismayed by the eruption of anti-Semitism in France during the Dreyfus Affair at the end of the 19th century, Herzl became Zionism's founding father. Long before the Holocaust, he concluded that Jews could find safety only in a national...