In 1946, the always eloquent Winston Churchill made a speech describing the fate of East European nations occupied by the Soviet Union and coined a phrase that became a permanent and vivid part of the political language. He said an "iron curtain" had descended across Europe.

That iron curtain has been rusty and leaky - at least in some places - for many years. Now the restless peoples of the communist East Bloc may be starting to tear it down.All across Eastern Europe, from the Baltic states of Latvia and Estonia on the north to Yugoslavia on the south, nations are in political ferment. In Poland, Hungary, Bulgaria, Czechoslovakia, East Germany, and Romania, there is unrest, demonstrations, new ethnic awareness, and a sense of change.

It must be emphasized that this is not revolution. There is little violence, although blood has been spilled in ethnic clashes in some places. But there is a liberalization of policies, shakeups among communist leaders, a rising tide of pressure from heretofore voiceless people against those at the top. Even communist regimes cannot entirely ignore this.

In most cases, there is a strong desire for the withdrawal of the more than 560,000 Soviet troops from the region and for closer ties with neighbors to the West.

This unrest can be traced to three sources:

1. With political and economic reforms being pushed in the Soviet Union itself by Mikhail Gorbachev, there is a growing sense of opportunity, of change, in the East Bloc nations as well.

2. The feeling that change is needed is fed by the economic problems of the East European countries. There is widespread recognition among both the leaders and the citizenry that they are slipping farther and farther behind the West in every way.

3. Despite the fact that more than 43 years have passed since the end of World War II and new generations have arisen, those East European nations still have ties to the rest of Europe. There was a time when they were independent countries, associated with the West both economically and politically. The awareness of that historic position is still strong in those small lands.

Where will it all end? Perhaps Gorbachev's "glasnost" will fail in the Soviet Union, or hard-liners will return to power in another administration. But the tide of change may be too strong to resist without resorting to tanks. It may be quick or slow, but there is no denying that such a tide is running - and it is deep.

In any event, the people of East Europe are reminding the world of an important lesson: No matter how long or hard various dictators try to repress it, mankind's inborn impulse for freedom never can be completely extinguished.