Cultural Extinction

I've just finished reading the book: Anti-Americanism, by Jean-Francois Revel. In the book, he lays out the case that the reflexive anti-Americanism of Europeans (with a particular emphasis on his native France) is often simplistic, self-contradictory, ill-informed, and counterproductive.
The most interesting section of the book to me was a chapter about cultural protectionism. The thrust of his argument is that it is impossible to protect a culture by building a wall against outside influences. He specifically argues against the French trying to protect their culture from American influence, but I think the lesson is to be heeded in this country as well (a similar cultural protectionism, or more accurately isolationism is sometimes evident in this country, particularly in certain movements on the right side of the political spectrum). Revel states: "The idea that a culture can preserve its originality by barricading itself against foreign influences is an old illusion that has always produced the opposite of the desired result. Isolation breeds sterility. It is the free circulation of cultural products and talents that allows each society to perpetuate and renew itself." Put another way, building a wall around a culture nearly always leads to cultural stagnation. An example of this cross-pollination of ideas is the rise of existentialism. Nietzsche was influenced by the ideas of the French moralists, and in turn his writings influenced French philosophers like Sartre, Camus, etc. during the following century. Other examples are endless. I think this is a concept often forgotten in times like this when nativism seems to be on the rise.