This treaty is a mess, but it will free Europe to do more important things

When the leaders of the European Union (except for the curmudgeonly latecomer Gordon Brown) gather this morning at Lisbon's Jerónimos monastery, to sign what was once intended to be a European constitution, they will be congregating in a glorious building in Portugal's distinctive Manueline style, they will be welcomed by a prime minister called Socrates, and they will be endorsing a dog's dinner.If I were them, I'd concentrate on the architecture, and the good lunch afterwards, in the former riding school of a royal palace. Wonderful city, Lisbon. Pity about the treaty. In the English version I have downloaded from the official website of the European Union, it has 175 pages of treaty text, 86 pages of accompanying protocols, a 25-page annexe, renumbering the articles in existing treaties, and a 26-page "final act", which includes no fewer than 65 separate "declarations". And that's just the English version; it will be disseminated in all the 23 official languages of the EU and - a detail buried in declaration 16 - in several non-official ones as well. Since the mere printing of the treaty in all these languages will require the destruction of several forests, it is hard to reconcile with its own commitment, in a new Article 2, to protecting the environment.

Many of the qualifying declarations are the result of interventions by Europe's awkward squad, which at the time the treaty was negotiated consisted of Britain and Poland under the Kaczynski twins, and now consists of Britain. Several of them are the result of translation into euro-legalese of Gordon Brown's "red lines", designed to protect him from Eurosceptic onslaught and save him from a referendum. (Denmark has just helped too, by deciding not to have a referendum.) They include pesky and largely pointless reservations about what should be one of the main benefits of this treaty - mechanisms for a stronger, better coordinated European foreign policy.

Elsewhere, 16 member states declare (number 52) that they still like the EU's symbols: its flag, anthem and motto ("United in diversity," in case you had forgotten), the euro and Europe Day on May 9. Well, bully for them. The list of signatories does not include France. Does this mean France disapproves of these symbols? And if we are "united in diversity", why do only 16 out of 27 member states unite to endorse this motto?

I am, however, delighted to see that my all-time favourite from earlier versions of the would-be constitution has survived. I hereby award the Salvador Dalí prize for the most surreal EU treaty declaration to number 58, in which the governments of Latvia, Hungary and Malta solemnly declare that the spelling of the name of the single currency on banknotes and coins "has no effect on the existing rules of the Latvian, Hungarian or Maltese languages". What is it, we wonder, about the word "euro" that so horribly twists Latvian, Hungarian and Maltese tongues? And what is the intended effect of this declaration? Is the fear that, but for this prophylactic incantation, the very word "euro" will act like some sort of semantic polonium, slowly devouring the organic substance of the Latvian, Hungarian and Maltese languages? I think we should be told.

To my left, there squats this monstrous 312-page spotted dick, plus copies of earlier treaties without which it cannot be understood; to my right, an elegant, pocket-sized, burgundy-coloured volume of just 60 pages, which contains both the Declaration of Independence and the 220-year-old constitution of the United States of America, with all subsequent amendments. "We, the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquillity, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity..." begins their effort. "His Majesty the King of the Belgians..." ours begins, and proceeds, through a thicket of presidents and crowned heads and a reference to completing "the process started by the Treaty of Amsterdam and by the Treaty of Nice", to this inspiring first article: "The Treaty on European Union shall be amended in accordance with this article." It then provides for the addition to the existing treaty preamble of some of Valéry Giscard d'Estaing's frightful waffle from the failed constitution. "Ach, Europa!" as the writer Hans Magnus Enzensberger once exclaimed.

It's painful to recall that ours was once meant to be something like theirs: a noble, clear statement of what our union is, how it works and the values it stands for, in muscular prose. That was the hope of at least some in Europe when we set out on this journey six years ago - and not just among the Euro-elites. In a Eurobarometer poll conducted in autumn 2001, two-thirds of those asked said they thought the EU should have a constitution. Even in Britain, the figure was 58%. What a falling-off there has been. We set out to give ourselves a constitutional banquet and ended up with a dog's dinner.

Yet the European Union continues to function and grow. "Eppur si muove" (And yet it moves) - Galileo's legendary defiant sigh - is perhaps the true, secret motto of the European Union. Our leading expert on the EU's institutions, Professor Helen Wallace, has just published a report on how the EU has been working since the great eastward enlargement of May 2004. Against sombre predictions of gridlock, she finds that it has continued to work rather well, through pragmatic adaptation and non-treaty reforms. Now this amending treaty of Lisbon, modest and hedged about with qualifications though it is, should enable the union to work just a little bit better when - assuming all 27 member states ratify it - it comes into force in January 2009. But a noble constitutional document, comparable to that of the United States, it is not. It more nearly resembles the instruction manual for a forklift truck.

In itself, it will do nothing to convince Europe's citizens, or the rest of the world, of what the European Union is good for. But it will help the EU to do things that may convince them. Now that the end of this long, disappointing constitutional debate is at last in sight, it should free us to concentrate on what this union does, rather than what it is, or says it is. In fact, the EU will define what it is by what it does. Will it help to create jobs, strengthen a free-trading world, encourage development, or combat climate change? What can it offer neighbours who will not become members, in the arc of crisis that surrounds us, from Murmansk to Casablanca? We cannot wait until January 2009 to address these questions. By then, a new American president will want to hear our answers.

A short walk from the Jerónimos monastery, down the estuary shore that leads to the Atlantic, is the magnificent tower of Belém, a gleaming white Manueline fortress that Europe's early modern explorers would have passed as they sailed out to discover new worlds. After their doubtless excellent lunch, today's European leaders should take a digestive stroll to the tower of Belém, and contemplate the wider horizon.

Timothy Garton Ash