One of the architects of the modern EU, Francois Mitterand, once said: "I'm afraid that when Europe's body is reunited it may lose its soul." Some people feel that is happening right now -- and that immigration is largely to blame.
Immigration has been called the most potent political issue in Europe today. It can certainly be a very emotive one.
On one side, there are people who argue for a very open handed approach to immigration. On the other are people who call for tighter immigration laws because, they claim, immigration may bring higher levels of crime or jeopardise traditional values.
Yesterday, the Daily Mail newspaper reported that according to Government experts, 'The soaring birth rate among immigrant mothers will soon become the main driver of Britain's rapid population growth.'
'Immigration,' said the newspaper, 'has been the biggest factor in increasing the population in recent years, and with millions of new arrivals starting families the birth rate is soaring. Almost a quarter of all babies in Britain are now born to immigrant mothers.'
No doubt, figures like these will raise the heat again in the ongoing debate about immigration and multiculturalism.
The question on which our minds should be focussed, though, is not whether we should allow immigration, but it should be managed.
Governments need to focus on this question: how many people can the system support; what kinds of people, with what skills and experience, do we need to import; and how quickly can we expect newcomers to assimilate?
Immigration brings many benefits to a society. It can, for example, bring a creative and cosmopolitan edge in fashion, food, the arts and architecture and entertainment.
It can also bring economic growth. Countries with declining and ageing populations - like those in most of Europe -- need to import immigrants to produce the wealth that will keep their standards of living high.
Without immigration, they'd face a pension crisis, changes in work patterns, shrinking cities and massive health care costs. Besides, immigrants will often do the jobs that local people refuse to do.
For all its benefits, of course, there are challenges which should not be underestimated - challenges for the host nations, and on a personal level, for those who are migrating.
I've had the privilege of being an immigrant twice in my life. My wife and I and our children moved from Australia to Denmark and some years later to the UK. I can tell you from experience, being an immigrant is in both exciting and daunting.
Many people value the cultural diversity that comes with multiculturalism, but they're afraid that too much immigration will place extra pressure on already strained local services, such as hospitals and schools.
And then there are pressures on jobs. In Europe, most immigrants are of working age. Some people are concerned that as the EU moves further eastwards, new waves of migration will threaten jobs in the West. Of course, immigrants of working age may be less likely to consume services like health care and education -- and they can pay more in taxes.
In the post-9/11 climate, the fear of terrorism is an obvious challenge too. Governments are worried not just about importing terrorists, but about giving shelter to people who will assist or facilitate terrorist actions. Sometimes, in responding to these threats, governments can go too far the other way, closing the door to genuine humanitarian concerns, like resettling refugees and asylum-seekers.
Perhaps the greatest challenge in the management of modern immigration, though, is what some have called 'cultural conquest'.
Some commentators already believe that Europe may one day be swallowed up into a new entity they call Eurabia, with a predominantly Muslim population - perhaps before the turn of this century.
I think that may be a little extreme. It's true that right now Muslim birth rates in Europe are way ahead of the rest of the community. But within a few generations the birth rates of immigrant populations tend to come back into line with the mainstream.
And, while Muslims make up a higher proportion of the youth community than they do society at large, this isn't necessarily a social problem unless it is combined with poverty, unemployment and long-term alienation - as we saw in France during the riots of 2005.
But there is a valid question here. How do we keep our doors open without compromising the values on which our civilisation was built?
The cause of immigration isn't helped by the stories we read in our newspapers, about young people who appeared to be well assimilated only to commit crimes in the name of radical Islamism. That's exactly what happened with the London Underground bombings and the murder of a Dutch Filmmaker in 2004.
However, before we cry too loudly that other cultures are going to swallow us whole, we should ask ourselves one very important question. What exactly are we trying to assimilate people into? If our culture is weak enough to be overrun, why is that?
If the West is open to cultural conquest, it may not be so much because of the strength of other cultures, but the weakness of our own cultural convictions - and the religious worldview from which they were historically derived.
Secularism may offer us no balwark against the 'cultural conquest' which some seem to fear.
The debate regarding levels of immigration will rage on, but we must take care not to step into xenophobia or stereotype, while recognizing the strength of our traditional cultural values.
In short, we must stop apologising for the strengths of our past and start building on them a platform for the future.