A reporter goes to Kampuchea (Cambodia) partly in the hope of learning more about how and why the reign of terror occurred here from 1975 to 1979.
There must be a few lessons in this for mankind, something that might prevent this from ever happening again.
One of the reasons the Vietnamese-supported government here admits Western reporters to this country is to show them new evidence of the killings, in this case newly discovered mass graves. Few who see these graves could doubt that they are real.
But what happened in Kampuchea has been fairly clear for some time now. Hundreds of thousands of Khmers - not combatants but civilians - perished from executions, overwork, and starvation during the reign of the Khmer Rouge, radical communists headed by then Premier Pol Pot. But even after a reporter has listened to a number of the survivors of this holocaust tell their stories, the ''why'' of it all remains a matter for conjecture. Even some of the survivors themselves seem puzzled as to how Khmers could have done this to their fellow Khmers.
''My two children, my parents, and my husband were killed,'' said a middle-aged woman named Mau near a mass grave to the south of Phnom Penh.
''My husband was a farmer,'' said the woman, almost shouting with anger. ''I never knew what my husband's crime was.''
''They said that my husband was a colonel,'' said another middle-aged woman named Suon Chanthi at a town in the southwest of Kampuchea. She had lost her husband and two of her children. ''But my husband was a teacher, not a colonel.''
''They accused me of working for the CIA and the KGB,'' said Khuy Sien, the mayor of the city of Kampot.
In 1977, the Khmer Rouge had insisted that the official, then a teacher, worked for both the American Central Intelligence Agency and the Soviet intelligence service, the KGB. The accusation didn't make sense. But the man had had enough warning to know that he must run for his life, and he did.
When one asks officials here their view of what happened during Kampuchea's long nightmare, one gets what has apparently become a standard answer: ''The Khmer Rouge were following the example of the Chinese Cultural Revolution.''
But one protests that while the Khmer Rouge may have borrowed ideas from China's frenzied, self-destructive Cultural Revolution of the 1960s, the Chinese radicals never went so far as the Khmer radicals did.
''Well,'' comes back the official answer, ''the Khmer Rouge were illiterates. . . . They followed the practices of the Chinese even more stubbornly than the Chinese themselves did.''
For the Vietnamese Communists and their Khmer proteges in Phnom Penh, that is a convenient belief to hold to. It places blame on the Chinese enemy. But it hardly provides all the answers. And the Khmer Rouge leaders were hardly illiterate. One of them, Khieu Samphan, holds a doctoral degree from the University of Paris.
If one looks to Prince Norodom Sihanouk, the former chief of state, for answers, he provides little help. Sihanouk cooperated with the Khmer Rouge and then became their prisoner. Without providing much supporting evidence in his book ''War and Hope,'' the prince asserts that Hitler was the hero of Pol Pot and his lieutenant, Ieng Sary. Sihanouk describes the Khmer Rouge soldiers who served under them as ''addicted to torture,'' but in the end Sihanouk seems as baffled as everyone else over the cruelty of the Khmer Rouge.
Some Western liberals and critics of the US bombing in Kampuchea seem to think that the ferocity of the bombing drove the Khmer Rouge into a rage against the cities that bombing had protected. But that argument too easily absolves the Khmer Rouge of responsibility.
Hatred of the cities was part of the story. But the Americans had at times bombed other parts of Indochina more heavily - parts of Vietnam and Laos, to be specific - without such a bloodbath resulting.
In the end, a reporter returns to some of the same conclusions that he drew in the spring of 1975 when the Khmer Rouge took Phnom Penh: They came to power much less sure of themselves than their Vietnamese counterparts. They saw enemies everywhere, and their cadres were badly trained.
They were trying to impose ideology on a strongly Buddhist people, many of whom opposed them. They did not have the administration or the rice to run the city of Phnom Penh or to feed it. In some cases, young, uneducated Khmer Rouge soldiers went out of control. In retrospect, one must add, as Stephen Heder of Cornell University does, that Khmer Rouge leaders seemed to live in a fantasy world as to how far they could go in transforming a deeply religious, peasant society.
''But the whole thing is still inexplicable to many of those who were there and even to many of those who carried it out,'' said Heder, a Khmer-speaking scholar who has interviewed hundreds of Khmer over the past several years.