On the day when East Germans received West German marks, an act signaling the reunion of a German nation torn in two since World War II, the Associated Press moved a photograph out of East Berlin.

It showed a line of children standing on a sidewalk and peering expectantly into the window of an East Berlin shop. Displayed were items for sale -- crayons, pens and books can be seen inside the window. From the fascinated, eager expressions on those young faces, it was obvious that these are goods the children have not had but want and will possess.

That single photograph fulfills the cliche: It is worth much more than a thousand words, for the story it tells is instantly understood by all. It captures an enduring human response and freezes a moment in history. With no commentary necessary, it tells us that something profound has happened. A turning point has been reached. The world will not be the same again.

For Americans, this scene and others like it portraying the knitting together of a uniquely, and unnaturally, cleaved society have a remote quality. They both exhilarate and somehow vaguely trouble us. They are certain to have an impact on our lives, we know, but we cannot pinpoint how. Nothing in the American experience, not even the bitter divisions engendered by the Civil War, prepares us for them.

Germans, too, are facing some of the same questions, as a letter from a woman in West Germany to an American friend powerfully expresses. It puts into words better than anything I've read the hopes and fears and the tangle of emotions confronting Germans.

The writer began by trying to explain to her friend here why, last fall, thousands of East Germans "simply got up to leave the country because they thought they could not stand the situation any longer. They simply walked out, leaving everything behind and hoping that life would be more worthwhile over here."

Apologizing for "my lousy English" and hoping that "you will still understand what I mean to say even if it is not very well expressed," she wrote about what it is like to have friends who haven't seen each other since 1945 and who now have children and grandchildren who have never met.

"We feel they belong here, belong to us, we have the same roots," she said of the East Germans. "This feeling of belonging together is stronger over here {in the West} than on their part. For more than 40 years, they were told that we are enemies. They had no possibility to inform themselves because they could not (or few could) watch our television programs. They had no western newspapers . . . . They have been told what the government wanted them to know and think and believe, and this is still going on in a way. . . .

"The friends who visit us are difficult to talk to when it comes to political questions. They are not used to saying what they think in a bigger circle. They are overwhelmed by what they see in the shops ( . . . {it} is like a fairy tale and many things they have never ever seen). They are also surprised that people are so friendly to them, that they talk to them in the streets or trains. Everybody talks, they say; they are not used to that.

"But at home, when we asked about their impressions of the atmosphere, in general, not concerning all the goods like food, clothing, toys, etc., they don't know what to say, and we feel they are simply not used to talk openly.

"My sister, for instance, invited two of them (our age) to Corsica last year . . . and they thought the island and Paris (where they stopped one night) were simply wonderful. But, they said, we shall not tell anyone at home where we were. There is so much envy. Well, that was in September and things have changed so rapidly. Everything is different now . . . .

"They have to learn democracy as we did after the war. We had the big help of America in every respect then. I feel they need help, too, not only that they have no money for paper, telephones, computers (they really don't have telephones in their offices), typewriters, etc. They don't know how to manage it at all.

"When you hear them speak in the television, you find they have another language, full of rhetorical phrases and cliches. They all use the same expressions and sentences. They all seem to say the same in the same words. It is difficult for me to describe. But I am sure you know what I mean."

Multiply those words a million-fold, and you begin to understand how difficult and fateful a drama is beginning in Germany. It is, quite simply, one of the most extraordinary stories of this century.