Levy can retain all the things he likes about his native culture -- work ethic, religion, "cabbage soaked to death in chili and garlic" -- while rejecting the parts of his native culture that he didn't like so much. For instance, in Seoul where he grew up, everyone minds everyone else's business. He has his niche here; he listens to Rush Limbaugh on the radio. "In America, nobody cares," he said. "In Korea, to have a different opinion from others in the group is to court social isolation, but not here."

The second person Guest tells us about is Ayaan Hirsi Ali, who comes from Somalia. She learned as a child how to protect herself from men who might be after her in Somalia. She fled from Somalia to Kenya; her family wanted to put her into into an arranged marriage, so she fled to Holland and claimed political asylum there. "She was amazed by how nice it is in Holland," Guest tells us. The police were friendly and helpful. Hirsi Ali got a job as an interpreter and began working with women who'd been beaten by their husbands. "Vast proportions of the women in these shelters came, like her, from immigrant Muslim backgrounds." The social workers didn't understand why the women weren't supported by their families -- who by and large supported the husbands.

Ayaan Hirsi Ali began to say critical things about Islam, and "this went over badly with local Muslims in Holland. One fanatic stabbed the director of the movie to death and left a note pinned to his chest telling Ayaan that he was coming after her." She left and came to America. Guest asked her how she was doing, having broken with her native culture and living now in America, and she said that can be done here. "At a think tank in Holland, where she was before -- they were linked to political parties...whereas in America there's a multiplicity of think tanks, and if you ask an interesting question, someone's going to say, yeah, that's an interesting question, follow that." She's been amazed by the speed with which people invite her into their homes. Being overtly atheist has not been a problem here, although this is a country where people self-identify as religious. "When people ask if I'm religious, I say no, and people say they'll pray for me; they don't kill me."

Dennis Downing is English. About a decade ago the government decided to ban fox-hunting. (There was a 900-page report drawn up which indicated, Guest says, that being torn to pieces by dogs was an impediment to the quality of life of the fox.) Once the ban came into play, Downing moved to the US, and now works with the hunt in Virginia. The thing he loves about America is that if you have an unusual hobby, people leave you alone. "That's guaranteed in America," Guest says. Even if fox hunting were banned in Virginia, there are many other states. That's the benefit of the decentralized culture here. "You can practically choose what kind of legal system you live under." If you want bike paths, e.g, move to Portland, OR. There are side-by-side counties in Kentucky, one of which is dry and one of which is called Bourbon county! The diversity is quite striking.

"In America," Guest says, "it doesn't matter what lifestyle you want, you can get it here." There are more foreign-born people in America than in any other country in the world -- 12.9%. (Editorial note: I'm dubious not about the 12.9%, but that this is more foreign-born people than anywhere else -- can anyone confirm or deny?) "People come from just anywhere and can fit in," Guest says.

Robert Lucas, a Nobel economist, has argued that migration matters so much because in his view the primary driver of innovation is the clustering of talented people. "America has this unparalelled potential for attracting talented people to come and live here." Why does that really matter? India and China are more populous than the United States, but China is going to get old before it gets rich because of the one-child policy. India's population will flatten later, but it will flatten. The US census bureau estimates that we're about 300 million people now, and could be 400 million by 2050 and 600 million by 2100. This is partially because we have higher birth rates than other countries, but it's also because of immigration.

There's also a high estimate which suggests that by 2100 we could have almost 1.2 billion Americans. In pure population terms, America would be the same size as India or China. He asks us, do you want the next hyperpower to be this fantastic, democratic, multi-ethnic America or to be a mono-ethnic and slightly chauvinist China? "I don't have any doubt about which I favor... I think America would be the one that would suck the least."

He leaves us with a quote from Michael Lind: "America is 'a Ponzi scheme that works.'"