Europe suffers from too much wine. Bravely, the governments of the Common Market's 10 member countries have agreed on a formula to curb the overproduction that price supports have made so expensive to the European taxpayer. The wine deal will make it possible at last to bring Spain and Portugal into the Common Market -- for purposes that have little to do with commerce, from the other members' point of view, and everything to do with supporting Iberian democracy. But now the whole enterprise is hung up on a Greek demand for more aid to the poorer Mediterranean regions -- i.e., Greece.

It's a nice example of the mixture of European idealism, commercial friction and regional rivalry that drives the politics of the Common Market. There's been a remarkable durability over the years to the consensus among Western European voters that the Common Market is above all a force for political stability. It's assurance against the kind of national collisions that led to the catastrophe of the two world wars. But there's also a certain ambivalence in Europeans' regard for their Common Market. By opening borders and enlarging commercial opportunities, it also pushes Europe through rapid social change -- and rapid social change, perhaps because of those two wars, is something for which the present generation of Europeans seems to have a low tolerance.

After Spain and Portugal turned to parliamentary democracy in the mid-1970s, their neighbors assumed that they would eventually join the Common Market and share the international institutions that would make that turn irreversible. That is the idealism on which the European community has been based from the beginning. But the idealists have always had to deal with practical difficulties on a large scale. Spanish agriculture competes directly with French and Italian products, of which the most conspicuous is red wine. The Common Market supports wine prices to protect a traditional way of life, and to slow down the rate at which those traditions fade. By agreeing on the new formula for wine production, the 10 governments have diminished this internal protection a bit as the price of supporting wider European democracy.

Bringing in two more countries, each with its own language and national culture, will mean a more heterogeneous Common Market than ever. That also raises concern among the European idealists, who keep pushing toward a community of countries increasingly closely knit together. But the European ideal continues to be stronger than you might think from listening to the incessant quarreling over money and farm programs. As its defenders would say, the Common Market always was a rather improbable idea. It is now in its 27th year and still -- noisily, slowly, but steadily -- gaining ground.