The enlargement of the European Union, which will almost double its membership of fifteen countries, is its most important project. The other tasks which the Union has in hand at the beginning of this century – the single currency, and the development of Europe’s role in foreign policy, security and defence – are of crucial importance, touching as they do on key areas of economic and political activity. But enlargement is an existential project. Bringing in the countries of central and eastern Europe, with more than 100 million people, will literally change the shape and dimension of the Union.