May 1, 2004 marks a watershed for the 15 current members of the European Union and the 10 accession countries. Eight of those - the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia - are coming in from the cold: for the past 50 years their economic and political development has been stifled by the communist system.
It was the bloodless "Solidarity" revolution in Poland, led by the charismatic Lech Walesa and supported by the moral authority of the Polish Pope, John Paul II, that set in train the disintegration of the rusting "Iron Curtain". This led to the introduction of democracy and market economics into Central and Eastern Europe.
Entering the EU means the accession countries will all have to give up some of their recently hard-won sovereignty. Yet they will do this gladly.
There are three reasons for this, the first being security. Economic integration will lead to increased western investment, which will aid the feeling of safety and stability that the eight former Communist countries have been enjoying since they joined NATO. Being a recognised, integral part of a free and democratic union will also reinforce their still-developing democratic processes.
Economic development is another factor. Fifty years of stagnation, or worse, were followed by the rapid introduction of a free-market economy.
This created an almost chaotic system that did not deliver the promised economic nirvana. Most of the eight have already paid the price of opening their borders to unrestricted levels of western imports, while their exports to the EU have been hindered by mountains of red tape, regulations and restrictions. Within the more equitable environment of full membership, they can expect to improve their importexport balance significantly.
At the same time, the rest of the EU will benefit from an expanding market within Europe and easier access to the huge and hungry markets of the former Soviet Union and beyond. Overall, the vastly increased economic opportunities will lead to more prosperity for all EU members, new and old.
But the existing members need to take care. The EU's cornerstones have always been the free movement of capital and labour throughout the Union. Retaining the free movement of capital while severely controlling movement of labour between the old and the new members is an obvious case of imbalance that could easily lead to resentment within the new members.
Migration from new members is being blocked for a transitional period by EUmembers except the UK and Ireland.
One can already see the growth in popularity of the rural nationalist Samoobrona (Self-Defence) party in Poland as a direct result of this, which does not bode well for the future.
The third reason why accession countries are so willing to join the EU relates to their standing in Europe. Here I speak as a Pole who arrived in Britain before my teenage years, was educated and has lived in this country for more than 50 years.
Thousands of people of Polish origin have been an unseen and undemanding ethnic minority: recognised only by our accents and unusual names, we have become fully integrated, but not assimilated. We have built thriving communities around our churches and clubs, celebrated our national days and enriched our joint culture. Many of us hold top positions in industry, the professions, arts and the media. Yet we have often felt our country of origin and, by extension, ourselves to be undervalued.
When I arrived here people looked for snow on my boots and for straw in my hair. Few knew of Poland's massive contribution to the history of the Continent. They were unaware, for example, of the relief of Vienna in 1683, when Polish forces under King Jan Sobieski saved Europe from the expanding Ottoman Empire. The great astronomer Copernicus (Mikolaj Kopernik), outstanding author Joseph Conrad (Teodor Josef Konrad Korzeniowski), double Nobel Prize-winning scientist Marie Curie (nee Maria Sklodowska) and the composer Frederic Chopin are just a few of the names adopted by others: Poles whose Polish nationality is conveniently forgotten.
The fact that the University of Krak"w, founded in 1364, is the fourth-oldest seat of learning in Europe is virtually unknown in the UK.
Polish culture, religion, customs and even food and drink, like those of the Czechs, Slovaks and the Hungarians, have been inextricably bound to the West. The Baltic states similarly lean westwards, as well as having some Scandinavian affinity.
I hope that full membership will increase tourism and show the West the wonderful natural resources that Central Europe has to offer. The huge unspoiled forests, lakes and rivers of Poland, the Carpathian mountains that Poles share with the Czechs and the Slovaks, and the superb climate of Hungary all wait to be explored. But there are also the beautiful old cities, awesome musical festivals, opera and theatre: the full richness of the cultural tradition of Central Europe.
European enlargement offers all of us an enormous opportunity. I just hope that short-term political gain is not allowed to spoil it, that we all grasp it with both hands, that we all explore and enjoy other cultures and splendours, that we all get to know each other better to our mutual benefit: that along with removing checkpoints and guard posts, we open the borders in our mind.
Jan Mokrzycki is president of the Federation of Poles in Great Britain