Thirty-one years ago - more than half-way back to the time when the second World War ended - there took place the first of a series of enlargements of the original six-member European Community. Garret FitzGerald writes.
These enlargements have quadrupled the number of member-states, and more than doubled the population of what is now the European Union.
I think it is fair to say that Ireland was the only one of those first three states joining the community which did so with enthusiasm. This was demonstrated by a referendum which secured 81 per cent support for joining the community in a poll which had a 70 per cent turn-out.
The peoples of the UK and Denmark took a much more jaundiced view of this process, and have remained sceptical participants ever since.
There were good reasons for our more positive attitude.
In crude financial terms, we were going to be major beneficiaries because we were the only member-state that would benefit from both of the main arms of the EC budget: the Common Agricultural Policy and the Structural Funds.
Moreover - to an extent that none of us fully appreciated at the time - we were also to become the biggest single beneficiary of access to this huge market as we had a far greater potential to attract industrial investment from outside the community than any other state. That was, of course, the key to the Celtic Tiger of the 1990s.
And there were other less material benefits. At a stroke our debilitating dependence on the former colonial power of Britain came to an end.
Curiously, the damaging neo-colonial relationship between Ireland and a Britain which from the end of the 19th century until 1980 was the slowest growing economy in Europe had not loomed large in our consciousness during the first half-century of political independence.
Consciously or otherwise, our politicians had distracted themselves and the electorate from that depressing reality by keeping us exercised about the grievance of partition.
However, once we escaped from the grip of that negative economic relationship, there emerged a sense of relief at the widening of our horizons beyond our near neighbour.
Not alone did this radical change in the Anglo-Irish economic relationship clear the way for a period of agricultural prosperity that cushioned our economy during the period of industrial adjustment to free trade, but it also enabled us to become self-confident in our relationship with Britain..
In economic terms, the effect of EU membership on the countries joining it today is likely to be a good deal less dramatic than was the case with Ireland.
First of all, the countries of central and eastern Europe have already experienced much of the impact of their liberation from economic dependence on the Soviet Union.
And because that liberation entailed a radical adjustment to the market system, as well as offering the prospect of new and better opportunities to sell their products, that process was painful in a way that we never experienced as it involved an initial sharp fall in output and living standards before the benefits of access to new markets could accrue.
Next, because over the past 30 years the external tariff of the EU has been dramatically reduced by global trade negotiations, the benefits of entry to this union in terms of increased exports will be much less dramatic than was the case with us in the 1970s.
Again, farmers of these central and eastern European countries are not being accorded immediate access to all the benefits of the Common Agricultural Policy as we were.
And after two decades of downward ratcheting of EU tax revenues as a result of a global swing to the right stimulated by Reagan and Thatcher, the Union that those countries are now joining is a good deal less generous towards poorer states than was the case when we joined 30 years ago.
The benefits that new member-states will secure from EU Structural Funds will compare unfavourably with what we received - these for over 20 years added almost 5 per cent annually to our GNP.
It should be added that in terms of output per head and living standards, especially in rural areas, all but Estonia of the new member-states of central and eastern Europe are a good deal further behind the existing member-states than we were 30 years ago.
Their output and income per head is on average 60 per cent below that of the existing member-states, whereas the corresponding shortfall in our case was 40 per cent.
Finally, the demography of these states is much less favourable to long-term growth than ours was when we joined in 1973. Only 17 per cent of their population are now under 14 years of age, whereas in 1973 over 30 per cent of ours was in that age cohort.
Thus they have much less prospect of securing the kind of employment growth that made possible the 8 per cent annual output growth of our Celtic Tiger years.
All that is the downside of entry to the union, about which I had to warn a Bulgarian audience on Thursday evening last, and about which I shall be speaking in the Czech Republic and Romania in the weeks ahead. But, of course, that is only part of the picture.
For since they began to recover in the mid-1990s from the initial shock of adjusting to a market system, the economic growth rate of the eight central and eastern European countries which are joining the EU today has on average been two-thirds higher than the growth rate of western Europe.
These countries have a real potential for growth that offers them a prospect of catching up on the rest of us. The only question is how long that catch-up process will take.
The experience not just of Ireland - which is something of a special case - but also of countries like Spain and Finland has shown that once inside the Union growth can accelerate significantly.
I would not be surprised if in the years ahead a number of these countries expanded their output at a rate twice as fast as western Europe.
In this process they will need help from the rest of us. Already Irish people are to be found in all these countries, helping their political and business leadership to learn from our experience.
This is a process through which we are securing valuable goodwill and are offsetting the temporary damage to our future relationship inflicted by our politicians' failure to campaign during the first Nice referendum.