Forty-seven years after the Treaty of Rome, EU leaders sign a magna carta that has built on all earlier foundations, writes the Taoiseach, Bertie Ahern.
Today, when we sign the European Constitution, Dermot Ahern and I will join our colleagues in the very same room in which the Treaty of Rome was signed in 1957. The historic symbolism is powerful.
The European Constitution will replace existing EU treaties. But it is building on the firm foundations they offer. While it makes some valuable changes, it is fundamentally a clarification and a consolidation of what has gone before.
Since 1957, what is now the European Union has been transformed. It has enlarged from six original members to 25. Further growth is in prospect. From its original focus on heavy industry and agriculture, the Union has over time been given extra responsibilities, in areas as diverse as the environment and action against cross-border crime.
The world around it has also changed hugely. The Treaty of Rome was signed before the Berlin Wall was built: after it fell EU membership was a beacon for those re-emerging democracies who are now our partners. Today's turbulent global scene offers challenges quite different from those faced during the Cold War.
As time passed, the original Treaty of Rome has been amended and added to by numerous other treaties, leaving us with a complex tangle of texts.
Through all of this, the European Union has remained true to its core purpose: security and prosperity in a Europe at peace with itself. In working together, Europeans have become friends and partners.
We in Ireland know better than anyone how Union membership can help transform economic performance - and the single market in particular remains vital to our future.
When work on the European Constitution began, there was an awareness of the new challenges faced by the Union, including the need to connect better with its people.
But we also knew that the existing institutions and policies were fundamentally sound. This balance between consolidation and reform is reflected in the final outcome.
Given that the European Constitution is to replace and subsume the existing treaties, it inevitably contains a substantial amount of necessary detail on specific policy areas. But its opening section - the first 60 articles - sets out the basics in a clear and understandable way.
The Union's values and objectives are defined. So too are the principles which underlie its powers and how they are exercised. It is made crystal clear that the Union only has those responsibilities the member states have unanimously agreed to give it. And the limits of those responsibilities are set out.
Where the European Union does have a power, obviously Union law has primacy over those of the member-states. The alternative would be anarchy, if people did not have to implement the rules they have agreed. But the European Constitution does not replace national Constitutions, which remain supreme in the national sphere.
An important element of the European Constitution is the enhanced visibility it offers to the protection of rights. The European Union is to become a party to the European Convention on Human Rights - thus meaning that it will be subject to the same external scrutiny as the member-states.
And its own Charter of Fundamental Rights sets out clearly in one place the various rights European citizens enjoy, and which must be respected by the EU institutions and the member-states when they implement EU law. This is a major development.
Contrary to what some European critics have said, the European Constitution does not try to prejudge the substance of the Union's social or economic policies. A broad and balanced framework is laid down, which enshrines core principles such as the free movement of goods, services, capital and of labour.
For the first time, and arising in part from an Irish initiative, there will be a "social clause" setting out social objectives to be taken into account in all policies. But, and quite properly, the text is neither a neo-liberal nor a socialist document.
Reform of the institutions will help make the larger Union function more effectively. The equality of member-states continues to be a basic principle in relation to the composition of the Commission and the Presidency of the Council of Ministers - where in future we will work in teams of three countries. The new posts of President of the European Council and Union Foreign Minister should enhance coherence and continuity.
I strongly welcome the greater role the Constitution gives to national parliaments, above all in vetting whether a Commission proposal deals with something better done at national level. And there is a new possibility for citizens to petition the Commission directly to take action on an issue of concern. The Council of Ministers will legislate in public, and the directly-elected European Parliament will also have extra legislative powers. All of these initiatives add to democratic accountability in the Union - an important objective of the whole process.
In the European Convention and the subsequent Inter-governmental Conference (IGC), it was possible to resolve Ireland's few outstanding national concerns to our satisfaction.
We maintained complete unanimity on tax matters, and full equality in the Commission. We also were able to agree arrangements to protect the distinctive elements of our legal tradition.
Importantly, while the European Constitution should further enhance Europe's capacity to act internationally, including in support of the UN - as Secretary General Kofi Annan stressed while he was here - nothing in it affects our traditional policy of military neutrality.
The Constitution brings to an end an intensive period of constitutional reform for the European Union. These reforms have given Europe, a single market, a single currency and effective foreign and justice policies.
Those who argue that further change is unnecessary are, I believe, wrong. There is an old saying that a "poor workman blames his tools". Europe is now equipped with the proper Constitutional tools. It is important to all of us to make it work.
I believe we have a European Constitution which will stand the test of time. The almost continuous Treaty-making of the past 20 years should now be at an end.
What we have is a comprehensive and balanced foundation document, which is also flexible enough to allow for the Union's future development.
I am satisfied that it will serve the people of Ireland and of Europe well for many years to come.