"Canada shall be the star towards which all men who love progress and freedom shall come," Sir Wilfrid said in that same 1904 speech. "There are men living in this audience . . . who before they die . . . will see this country with at least sixty millions of people." History records that these words were greeted with cheers, for Canadians were an ambitious people then. Today, as we see, they would provoke only brays of outrage and derision.

Beyond rank nativism, the case for immigration controls rests on little more than the force of convention, the human predisposition to think that whatever is currently the case is the natural order of things. "But people have always eaten people," the cannibal father says to his rebellious son in the Flanders and Swann song. "What else is there to eat?" Yet those who insist with such becoming displays of spittle on the eternal, obvious rightness of immigration quotas are ignorant not only of our own history - for the first 30 years of our existence as a federation there were no overall limits - but of the actual experience of the population growth they fear.

It is not abstruse economic theory that has consistently debunked Malthusian fears of "overpopulation"; it is the record of humanity over the last two centuries. The world's population has doubled since 1950. Yet world food production in the same time has tripled; total economic output has quadrupled. The commodities the Club of Rome predicted we would have run out of by now have never been so abundant: The developed world, for example, uses one-third less energy per dollar of GDP than it did 20 years ago. The air and water sheer numbers should surely have despoiled beyond repair have in fact grown cleaner in recent decades in many countries.

Want a Canadian example? Since 1980, the number of cars on Canadian streets has climbed 30 per cent; the number of kilometres driven has increased 20 per cent; the total number of litres of fuel consumed has declined. Sulphur-dioxide emissions, likewise, have fallen by one-third. Theory does, however, tell us why this is so. I am grateful to the many kind readers who wrote to advise me of the existence of Calcutta and Mexico City. But I never said there was no such thing as crowding, or pollution: only that neither is a straight-line function of population. It is no more meaningful to say the problem is one of "too many people" than it is to say there is too little land, or air. Human beings, that is, are not a given. They adjust to incentives. So long as the full economic and environmental costs of their actions are brought home to them, usually through the medium of prices, sometimes aided by government, so each must modulate his individual demands to reflect the general scarcity of resources.

Yet many people still believe not only that there is a natural population for Canada, but that by an amazing coincidence it is precisely at current levels. Sometimes this is expressed in terms of raw aggregates, as if the United States would be 10 times richer if its population were a 10th the size. More usually, it emerges as a concern for limiting density, or growth rates.

Yet among the top 25 countries on the United Nations Human Development Index, we find 10 of the most densely peopled spots on Earth, including such unbearable hellholes as Switzerland, Japan, the Netherlands, Barbados and Hong Kong. For that matter, for all the talk of Toronto and Vancouver being overrun, I don't see anybody in a hurry to leave either city. Both are much more interesting and livable places than they were 20 or 30 years ago, and would be nicer still, many urbanists agree, at higher densities.

Let us suppose there is some maximum sustainable growth rate. How exactly would we go about calculating it? How do we know we couldn't take in a million people a year? Germany in the 1950s absorbed 13 million refugees into a pre-war population of 39 million. At the end of the decade it had one of the richest economies in Europe - and the lowest unemployment rate.

At the time Laurier was laying claim to the 20th century, Canada was taking in 150,000 immigrants a year, or about 3 per cent of the population - three times current levels proportionally. If his words now ring hollow, if the country flounders aimlessly, perhaps it is because we forgot his second prediction.