"The French example presents an ideal laboratory experiment. France, like the United States, bases its sense of nationhood on a set of Enlightenment ideas about the rights of individuals in a society. France, much more than this country, also draws identity from language and an ancient cultural heritage.
But then immigrants began to arrive -- mostly former colonials from North and West Africa, people with darker skin and a different cultural and religious heritage. France essentially said to the immigrants: "Look, these are our ideals -- liberty, equality, fraternity . We're not adding diversity to the list." Eugene Robinson, Washington Post