Donald Trump's arrogance -- based on the enormous power the United States exercises in world affairs and his own acquisition of vast wealth -- has produced his frequent berating of President Zelensky of Ukraine, as well as his glib talk of making Canada the 51st state and of seizing Greenland, the Panama Canal, and Gaza.  It also lies behind Trump's disdain for the United Nations, where all countries -- the large and the small, the powerful and the weak -- have pledged to work for the common good.