Few now probably remember the stir caused by the then Governor of Central Bank Maurice Doyle, when he said that Ireland did not join the Common Market to become the North Dakota of a United States of Europe (USE).

It was Mr Doyle's reference to a possible USE which caused most controversy. But 20 years on, and knowing what we know now, the comment about North Dakota may be the more relevant.

I suspect the late Mr Doyle thought so too. If so, he was ahead of his time. Maastricht was still in gestation and monetary union was only a dream. Now, in the worst western European economic crisis since the war, the warning about the very differing fortunes of regions within nation states, never mind the rarer examples of pure monetary unions, could not be more apt.

The Irish should be the experts on this subject. We were part of a monetary union for around 150 years - first as a region of the United Kingdom of Great Britain and Ireland and then as a self-governing country which kept sterling as its currency.

In truth, the role of government in the 19th century was so limited compared with that of a modern state that it would be reasonable to regard the entire 150 years as membership of a monetary union, with little of the financial sharing which characterises advanced economies today. The Famine bailout from London was limited to say the least.

How are countries like Greece and Portugal to develop successful economies while trading in euro? More importantly, can Italy and Spain do so either?

If they cannot, the follow-up question is even more difficult politically. Can the monetary union survive without some greater sharing of resources - from the more productive, prosperous parts to the lesser - of the kind that goes on in modern nation states? That would involve the creation of at least an embryonic USE.

For Ireland now, attracting and holding foreign investment and creating the conditions for more and better domestic investment are key to economic success in the euro.

And the euro it probably will be. Last week's eurozone summit arrangements are the first click of a set of "golden handcuffs" which will lock members more tightly into the monetary union.

Too much talk about personal consumption and savings ratios is another distraction from what is required. Efficiency, not shopping, will make Ireland the - let's say Delaware (income per capita $33,000) - of a United States of Europe.