I pity the poor immigrant,” wrote Bob Dylan, “Who wishes he would have stayed home/ Who uses all his power to do evil/ But in the end is always left so alone.” The minstrel-poet from Minnesota was chronicling attitudes a generation ago, but his words seem especially apposite today.

Immigration is toxic now in most of the developed world. In Britain, Gordon Brown's Government seems eager to test to destruction its insistence that tolerance is the essential facet of what it means to be British. The incomparable bungling that resulted in illegal immigrants being hired among other things to police border security would surely be parody if it were not prosaic reality. It certainly suggested a rather new take on Mr Brown's famous promise of “British jobs for British workers” a couple of months back.

In Italy, Romanians are in the cross-hairs, after one of them was charged with beating and sexually assaulting a teacher. Last week the Danish Government won re-election only with the continued support of the anti-immigrant People's Party. Last month the Swiss party that goes by the same name got more votes than any party in that country since 1919, with the help of a campaign that included imagery such as a flock of white sheep kicking a black sheep off a Swiss flag. Anti-immigrant sentiment continues to boil in France and the Netherlands.

Europe, lest we forget, is the cradle of enlightened liberal democracy. In America, that Hobbesian pit of bigotry and general fascistic nastiness, overtly racist parties oddly don't seem to do so well as they do in gentle Europe. But here too, immigration is the most potent political issue in the country.

This week its saliency was underlined when Eliot Spitzer, the Governor of New York, was forced to withdraw an ill-conceived proposal to give driving licences to illegal immigrants. This was the issue that got Hillary Clinton into so much trouble recently when in the last Democratic presidential debate, she gave a classic non-committal, nuanced, focus-grouped answer.

With 12 million or more illegal immigrants in the country, voters are in no mood for overt displays of generosity. Populist anger defeated efforts to give them amnesty a few months ago, and the issue looks set to become perhaps the biggest issue of the presidential election campaign - especially if, as it is currently, progress in Iraq takes the war off the front pages.

Our political, intellectual and media elites ponder this turn of events with a disdainful eye. They shake their heads at the irredeemable bigotry of the masses and wring their hands at the primitive ignorance that drives the popular mood.

But our leaders should instead be looking hard at their own role in helping to create this rising backlash against immigration. It comes after 50 years in which, against their own will and better judgment, the masses have been directed to shed anachronistic and dangerous notions of national identity. In Europe especially, the multicultural worldview insisted that we should look with benign neutrality on global cultural diversity, to think of other cultures as no worse than our own, and in many respects quite a bit better. Patriotism equalled racism. National identity was incompatible with global peace.

So what happens when you spend decades suppressing national identity? Do you actually succeed in pouring us all into a great big melting pot? Or do you, in fact, simply nurture a subterranean sense of national selfhood; steadily curdling it over the years so that, when it reasserts itself, it is angry, illiberal and ugly? In Europe we see the consequences everywhere. The current mood, of course, is partly economic — the cheap immigrant stealing our jobs. It partly reflects heightened insecurity, especially the very specific threat posed by Islamists, the vipers in the bosoms of too many Muslim communities. But, as the Italian-Romanian incident shows, it goes much farther, and can take the unprepossessing form of raw and ancient hatreds.

America has, to its great fortune, been spared the worst excesses of multiculturalism. But it has not been completely immune. The current antipathy towards illegal immigrants is apparently about economics, but it isn't really. The US continues to enjoy solid growth, low unemployment and rising incomes for most Americans. As in Europe, the current sentiment is partly about security concerns. It is partly about a simple sense of fairness that asks: why should millions of people be able to break the law with impunity? But it also reflects a rising worry that the new wave of immigrants - mostly from Mexico - are not like previous waves of immigrants who made this country. Those earlier generations may have proudly asserted their ancient heritage, but they quickly integrated as Americans. There is an unsettling impression that many of the new immigrants are not following this model.

A small minority are actively separatist, trying to create little outposts of Mexico in the heartland. But even in its milder form - the refusal to learn English, for example - this modern immigrant mentality is troublingly different.

So now we have one hell of a mess. We - all of us - need immigration. We can't close our doors. In Europe, mountainous demographic challenges mean the only plausible supply of labour is from overseas. But even America cannot afford to be autarkic. It needs strong and steady flows of immigrants to power the world's most dynamic capitalist system.

Neither should we regard immigrants as merely a source of cheap labour. They can and do enrich our societies, feeding a diversity that broadens and deepens us all.

But our clumsy efforts to create deracinated “global communities” have badly backfired. In the end, we should not forget that immigrants are immigrants. That means they have come to us, not we to them, because of the opportunities and intrinsic appeal of our own societies.

Only by insisting that our own national identity and sovereignty is non-negotiable will we be able to continue both to welcome new immigrants and to maintain our chance at prosperity, and even survival, in a competitive and dangerous world.

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