The received Brussels wisdom, following the old view that a bicycle that does not go forward must topple over, is that failing to increase the union's membership from 12 to 16 must be a disaster. Yet this ignores the fact that the four applicants no longer face a stark choice between membership and isolation. The union has already shown itself willing to enter into free trade agreements that replicate many of the benefits of the Nafta deal between the United States, Mexico and Canada.
Yet failure would nevertheless be a blow. The loss of Norway would be regrettable but understandable given its abortive 1972 application. But were the Swedes to decide not to join, how long would the Danes contain their lingering resentment towards the Maastricht treaty? And how long before Westminster's Euro-sceptics begin to argue that while Britain stays out of the European exchange rate mechanism, it might as well stay out of the political union?
If the union were not to agree terms with the Finns and the Austrians, the prospective admission of poorer countries to the east would be gravely in doubt. A union so torn that it cannot admit four prosperous countries whose combined population it exceeds tenfold, and who would be net contributors to its budget, can hardly hope to overcome the tougher issues of admitting nations such as Poland, Hungary and the Czech Republic.
Yet that next stage of enlargement will be the most important in the union's history. Not only will the admission of East European countries bring huge economic benefits to both sides; it will also serve a strategic function. Ten years from now, the tension between a restive and unstable Russia and its smaller western neighbours may once again pose the greatest threat to the safety of Europe. A stable union that stretches from the Atlantic to the Russian border could be the best way to keep the continent prosperous and peaceful.