EVERY generation experiences moments that stun and shape its historical consciousness. In the crucible of a world war, the assassination of a young president or the landing of astronauts on the Moon, values are transformed and ideas born that become the touchstones for the future.

Today, on the heels of change in governments across the world, an old, haunting question poses itself anew to our generation, beckoning for an answer as never before. As hundreds of thousands of Berliners and their compatriots worldwide celebrate the political erasure of the Berlin Wall, Americans find again in the history of Europe our own future in liberal democracy and economics.

LOOKING only to the events of this past year, numerous images claim indelible places in our memory and imagination. Millions marched in China's capital for political reform this spring before they gathered in East Germany. Leaders in Poland, Hungary, Bulgaria have followed the Soviet Union's lead step-by-step in opening up totalitarian regimes.

Now pictures as defiant as a pair of young West Berliners, standing before a water cannon, ramming a post into the Wall, as inconceivable as hundreds of youths celebrating before the Brandenburg Gate, as simply staggering as a peak-capped East German border guard handing a flower to West German women seated atop the barrier, spread throughout the Western world.

Few events could generate such awe, such emotion, such sheer wonder on so many personal levels.

FOR young Americans, however, the time poses perplexing questions.

The mere thought that the Wall could crumble into irrelevance so quickly runs counter to the "world views" instilled in those growing up in the age of Nixon, Brezhnev and Reagan. Indeed, the cultural landmarks used to define a "post-war world order" were planted before most of us were even born: Prague 1968; Berlin 1961; Hungary 1956. Even in Asia, Mao's Cultural Revolution and America's involvement in Vietnam began and reached their peak in the mid- to late 1960s.

Thus, even as events offer great promise, they simultaneously remind us of a past we would rather overlook. The moments of shocking history--which must be confronted--simply prove again the intractable nature of opposing ideologies and economic systems.

So we sit on the sidelines watching, with our hands tied by uncertainty and our vision lacking the sharply focused lens provided by the past, as momentous events burst one by one around us. Inevitably, we ask, how could it be? What will happen now? Is there cause for fear?

BUT it is not only the youth who are adrift in doubt.

For days following the tumultuous firings and resignations of East Germany's Cabinet and Politburo, there was virtually no word from the West's foreign policy intelligentsia. The silence continued for two days after the political dismantling of the Wall.

Now at last, these experts and governments are embracing the changes that have flowed too fast for political comprehension in Eastern Europe, all the while issuing dark cautions of the repercussions of a destabilized continent and a disrupted economic system.

But it is telling too, in this moment of generational change, that while the East looks to Mikhail S. Gorbachev and Egon Krenz, America reflects with longing back to the late John F. Kennedy, whose voice still rings resonantly from some younger, self-idealized national age, for answers. It would seem that the times are even ready for change in our own country.

WITH the rest of the world we learn rapidly that the difficulties remaining for the Germans and Europeans are vast. For reasons of superpower and continental security, reunification remains out of the question. The Western powers, hearing the echoes of the past--two world wars and inexpressible human horror--look to the recreation of a unified Germany in central Europe with unvoiced misgiving.

Economic integration of East Germany into the European Community is also impossible in the short run, we learn. Citizens in West Germany are already beginning to grumble over the housing crunch and economic drain induced by the Eastern immigrants.

It is the past we see again and again. This is not to deny that there is cause for great celebration and great joy for millions in Europe and their compatriots worldwide. There is. And there is great hope in Gorbachev's words for peaceful and calm change toward true self-government, toward social welfare and peace. But the reminder provided also by these great changes is how intractable, irrational and powerful the undercurrents of the old problems are, even as they take new form.