The German Von Eicken found, in this tendency of all human movements to provoke violent reactions, the master key of history. Every idea or institution passes into its opposite. For instance, Roman imperialism, which was created by an intense national consciousness, ended by destroying the nationality of rulers and subjects alike. The fanatical nationalism of the Jews left them a people without a country. The Catholic Church began by renouncing the world, and became the heir of the defunct Roman empire. In political philosophy, the law of the swinging pendulum may act as a salutary cold douche. Universal suffrage, says Sybel, has always heralded the end of parliamentary government. Tocqueville caps this by saying that the more successful a democracy is in levelling a population, the less will be the resistance which the next despotism will encounter.
But the pendulum sometimes swings very slowly, and oscillates within narrow limits; while at other times the changes are violent and rapid. The last century and a half, beginning with what Arnold
