Like a great glacier carving valleys, feeding rivers, and depositing soil, immigration is reshaping America's character and future -- her economy, workforce, family structures, demography, culture, cuisines, languages, and politics. Yet of all the first-order policy issues facing the nation, this may well be the hardest one for us to approach rationally. We are hardly alone, of course. Immigration also arouses fierce passions in France, Spain, Japan, and most other nations. But Americans feel a special skittishness and ambivalence about the subject. Our self-contradictions abound. Defining ourselves as a nation of immigrants, we also view immigration as a threat. Defending our autonomy, we also invite millions of strangers to come here, transforming our society Demanding secure borders against illegal workers, we also advocate the free movement of goods, technology, and capital. Growing global interdependencies further muddy the debate, making it harder to know who "we" are and what "...