The lights are going on again all over Europe. Fifty years after the totalitarian darkness descended upon them, the countries of what we used to call Eastern Europe are at last emerging into the light. With the revolutions of 1989, it may be said World War II is truly at an end.

A trip through Czechoslovakia, Hungary, Poland and East Germany reveals the extent of the wreckage the retreating tide of communism has left behind. Detailed observations await a longer forum but for now a few general comments - bearing in mind each country's situation is unique.

The first is that the economy is the least of these people's problems. This is not to minimize the disaster they face.

BELOW GREECE'S

Czechoslovakia, once among the richest countries in Europe, now has a standard of living somewhere below that of Greece. The average monthly wage in Hungary, one of the more prosperous of the East bloc economies, is about 5,000 forints - US$60, at the market rate of exchange. All but Czechoslovakia are deeply in debt, and struggling to prevent the collapse of their currencies.

Policy is far more lethal to an economy than mere war. The reconstruction of the Communist economies into what the reformers consistently refer to as a ''normal'' - that is, free market - system is a more daunting task than even that faced by the defeated Germany in 1945.

Such basics of a money economy as a proper system of accounts, the techniques of assessing credit risks and asset values, even income taxes and chequing accounts must all be laboriously put into place.

The wholesale privatization of state enterprises in which each country is engaged has been described as the sale of assets without owners, at prices without any basis in value, to people without money.

Yet there is, as Adam Smith said, a great deal of ruin in a nation. An economy is a remarkably resilient plant: put it into the light, give it the proper nourishment, and even the most bedraggled will bloom in surprisingly short order.

The most informed predictions after World War II held that West Germany would take at least 50 years to recover. It is now thought that East Germany will take five to 10 years to do likewise, and I suspect we may find it takes even less than that. In a few short weeks, the Solidarity government has already put in place the beginnings of the Polish economic miracle.

But how long will it take to clean up the air, choked with the brown coal burned in the factories and the leaded gas burned in the cars? How many years will it be before all those ghastly buildings, the peeling, filthy boxes of offices on the main streets, and the prefab boxes of flats in the suburbs, are torn down and replaced?

And how many generations before the ''moral pollution'' of which Vaclav Havel spoke in his first address as president of Czechoslovakia, the corruption of everyday human relations, the bribery and the petty hates and the lies that everyone lived by, has been cleansed?

When as much as one third of the population was involved in some way in spying on the rest, as in Romania, can a civil society be restored while both are still alive?

The East Germans are agonized by the revelation that many of those in whom they have just placed their electoral trust were paid informants of the secret police. The French are even now revising the lists of who was a collaborator and who was in the resistance in their politics. For that matter, they are still replaying the revolution.

Indeed, perhaps the greatest difficulty will be in delousing society of Communist influence, notwithstanding their removal from the formal offices of power.

One is most struck in talking to people there by their fear that somehow, however feeble and demoralized the Communists might appear, they would find a way to rule again.

It is not only that, as in Poland, the Communists control the army, the police and the vast nether reaches of the bureaucracy. The party has in every case huge resources at its disposal, and it will be a long and painstaking process to wrest these back.

WAR CHEST

Rude Pravo is still the largest circulation newspaper in Prague, not because people have much use for it, but because the Communists have all the newsprint. In Hungary, the Communists ran as no fewer than four separate parties in the recent election; in one of its last acts, the former government gave one of them several million forints as a war chest.

Small wonder, in the face of this endless chicanery, that people are still wary. Listening to them, one could not help but think of Dracula: they will not believe the regime is dead until they see a stake through its heart.