AT THE APOCRYPHAL first Thanksgiving dinner, a group of recent immigrants enjoyed a lavish meal, courtesy of Americans with a much longer pedigree. It is a metaphor worth pondering. This country would be, literally, pretty much empty were it not for the waves of migration here--the 17th- and 18th-century migrations from the British Isles and, unwillingly, from Africa and the 1840-1924 migration from northern, southern and western Europe. Not all these immigrants received as warm a welcome as the Pilgrims are supposed to have received at Plymouth; American history has its ugly episodes of nativism, rioting, and racial and ethnic prejudice. But immigration did, literally, make this country what it is. We are the product of people who uprooted themselves and, in most cases, chose to come here. Few other countries can say that.

Few other countries can say, either, that they are particularly welcoming to immigrants today. Most European countries allow those who wish to enter to do so only as guest workers; in many cases, they can be shipped out and have no rights where they are. Japan is culturally inhospitable to anyone who is not Japanese; Japan has exported jobs to lower- wage Asian countries rather than allow other Asians to come to Japan. And few Asian countries would allow Vietnamese boat people inside their borders in any numbers.

The United States, in contrast, has been generous and welcoming. Of course, there has been some friction as a result of the wave of immigration, mostly from Latin America and East Asia, that seems to have begun around 1970. High crime rates in Miami are attributed to migrants; there is angry reaction to the presence of Cuban refugees in Fort Chaffee, Ark.; there are fights between Vietnamese and local fishermen on the Texas Gulf coast. But compared with what happens in other countries, where immigrants are generally not allowed in or are widely shunned, or compared with what happened years ago in this country, this country extends a warm welcome.

That's something to keep in mind, not only during the forthcoming congressional debate on the immigration bill, but also when we think about our country generally. The tone of political debate in this country is negative; we dissect our problems and our weaknesses and give little thought to our accomplishments and our strengths. One of those accomplishments has been the creation of a strong and prosperous nation from a body of diverse immigrants.