People knew instantly. The Washington Post for Aug. 7, 1945, called the atomic bomb a "world-shaking event." It headlined a "new era of power," used the term "atomic age" and quoted from a presidential statement in which -- not for the last time -- a politician said atomic energy would someday be used for peace. The pope also knew instantly. "The use of atomic bombs has created an unfavorable impression on the Vatican," the statement said.

The microfilm of the old newspapers comes as a surprise. I had thought people in 1945 were unaware that a historical age had opened, that the bomb was not just a bigger, more efficient weapon, but a point of departure from which things never again could be the same. Certainly that is Richard Nixon's recollection. "We had heard about the buzz bombs in London and other new weapons . . . and I said, well, this is just another one," he told Time magazine. "I just assumed the war would go on."

Nixon's recollection is understandable. There was much to absorb -- too much. Between April and August 1945, a casual newspaper reader would have learned of the Holocaust -- the methodical murder of millions of noncombatants -- and then, only months later, of the atomic bomb.

It took time for the world to come to grips with these twin horrors. After all, it is only relatively recently that we have faced up to the Holocaust, only recently that names such as Mengele have become widely known and then, too late, the search for them launched.

We are only now beginning to assimilate these events because we are not talking about technical breakthroughs, intellectual achievements, gizmos in secret laboratories, but, instead, a new image of ourselves. Little wonder that we turned away from what we saw, from what the bomb and the Holocaust told us about ourselves. It was not a pretty picture.

Maybe our self-image is the last victim of World War II. The old romantic view of mankind, a vision of people as essentially good and on the path to getting better, has been vanquished by the data, by the number of victims and the reason for their deaths. In its place has been substituted a sickening reality. The smoke of Auschwitz and the smoke of Hiroshima, so different in their causes and their justifications, were nevertheless the smoke of mass murder. One speaks to the other. Once you have walked the perimeter of a death camp or even know of its existence, then you know what people are capable of. It ruins sleep to think of their weapons.

No wonder the insights and the doubts of August 1945 got buried. No wonder it took years to confront the Holocaust -- to establish the memorial programs, to request the museums, to demand the capture of the escaped criminals. Think of what we had learned. Think of the killing that was done -- and done, mind you, not by primitive peoples but by Germans and their allies, by Russians, by Japanese and, last, by us and our allies. These are the most advanced people on Earth and once, for reasons sometimes having to do with race hatred, they killed one another until the dead numbered some 50 million.

"Night" is the title of Elie Weisel's memoir of Auschwitz. It is a fitting title because the nuclear night and the "Night" of the Holocaust complement each other. Weisel's "Night" is what makes the nuclear night so frightening. It testifies to our madness. If the people of Beethoven and Bach, of Schiller and Brecht could incinerate the people of Kafka and Heine, of Einstein and Freud . . . if Germans in Berlin could want so much to kill little Elie Weisel of Hungary, then our fears are justified.

Now, with perspective these events of 40 years ago merge to provide a moral lesson. One Holocaust teaches that another, even bigger, is possible -- that if mid-century bureaucracy could have combined with science to produce the death of millions, think of what is possible now. Everything is improved except, of course, man himself. It is hard to look at what we have done, but it is necessary. Self-knowledge is all we have to hold back the nights.