THE refugee column, the immigration queue, the central rail or bus station daily pouring its recruits into the city: These are images that we think of as peculiarly characteristic of our times. But the globe that we know had been sculpted into the shape that it now has by vast migratory movements that began long before the fighter-bomber, the passport, or the train added impulsion or impediment to the process.To speak only of the last 100 years, it was migration that created, for instance, a populous and powerful United States, that underpinned the postwar national reorganization of Europe, that made Israel, that brought into being Hong Kong, Singapore, and Taiwan. Until recently, in spite of all the resentment and disruption that it has always brought in its wake, migration was seen as a positive force in human affairs: Indeed, the modern world could not have been made without it. Now we are in a newly fearful mood. The immigrant is a figure who seems to portend disaster: His departure from his own society speaks of trouble there, his arrival in his new place speaks of trouble there as well. Behind most discussions of migration today lies a picture of a world divided into a handful of wealth zones surrounded by slum hinterlands with even more chaotic badlands further out - city and favela writ large. The primary wealth zones are of course Western Europe, North America, the Gulf, a nd Japan. Lesser ones exist in Chinese East Asia (Hong Kong and Taiwan), South Africa, and Southeast Asia. The metaphors "Fortress Europe," the "Watch on the Rio Grande" are military: The citadels are under assault. In spite of Europe's fears, however, the numbers involved have been limited. Only 2 or 3 percent of EC residents (depending on the estimate of illegals) are recent migrants. In the US, migrants were responsible for more than one-third of national population growth in the 1980s, and the 8 million who entered the US in those years were the largest number for a single decade since 1900 to 1910. These migrant flows are producing significant political shifts in America, where anxiety about Hispanization is the American equivalent to Europe's worries about an Arab assault from the south and an invasion from the east. Nor is the fear of migration confined to Western countries. The Japanese are in a state of advanced neurosis about illegal immigration, which their wealth inevitably attracts, but which they see as a threat to Japan's homogenous culture. Places like Hong Kong, a society composed almost entirely of the children and grandchildren of migrants, go into spasms when asked to give refuge to Vietnamese, many of them of Chinese origin. It is hard to say how close to possible reality these various nightmares are. But it is obvious that migration touches late-20th-century man in a very vulnerable emotional place. It is part, after all, of a long process of globalization which has given rise in turn to a defense of the individual, of the particular, of the communal, and of the national against hostile forces. The irony is that the same techniques of industrial organization, of transportation, of mass culture, and popular education for a t ime served both the processes of nation-building and the processes of globalization. Powerful nations at least were able to elaborate their national identities (suppressing regional particularisms in the process) while operating in addition as centers for globalization. The last and greatest example was the US. But we now understand better than we did in the days of simple anti-Americanism throughout the world that "Americanization" was a process as hostile to an earlier kind of American national identity a s it was to the identity of other countries. The sense that cultural identity is at risk is significantly a feeling that is shared by both migrant communities and host societies, and it is the basis for extreme attitudes on both sides. The appearance of racist political parties in Europe has been paralleled by the growth of more assertive movements among migrants, particularly among blacks and Muslims. There are similar developments elsewhere. The moral complexities here are great. It is perfectly possible, for instance, to view third-world migrants as defectors, taking skills and talents away from poor societies to wealthy ones, and they may at some level so view themselves. The migrant then, even when he may also be a refugee from war or other trauma and not just a seeker after better opportunities, seems a threat to at least some members of the host society because he is a visible sign of changes which have not been willed or desired. He contributes to the sense that things are out of human control, and that precious values and traditions are being remorselessly eroded. The migrant himself may well be subject to similar emotions. He or his family have, by moving, strained their own cultural allegiance, and reaffirming it in the new place is difficult, sometimes provocative. The French constitution of 1791 affirmed "the liberty of all to move about, to remain, or to leave," and the notion that global freedom of movement is a human right lingers on. If so, it has been a right enjoyed historically only by a minority, and that will hardly change in the future. Nor will it ever be a right, however circumscribed, that is not fraught with problems for those who move, and for those who receive them.