I took pictures at the sites of some of the grisliest scenes of mass murder and torture in Cambodia and posted them on Twitter. Some of the photographs on display in Pnomh Penh were so gruesome that I could not look at them, other than to recognize what they were and look away. Nor did I enter the glass-walled monument at the Killing Fields, about 20 miles from Phomn Penh, stacked high with skulls, arrayed by age and gender. I couldn’t.

The Cambodian genocide is especially puzzling because it was directed by Cambodians against Cambodians, not against a particular religion or ethnic group. Pol Pot wanted to abolish all religions, all educated people. He wanted to reduce the country to an agrarian society, with no engineers or teachers or doctors. He came from a privileged family. He had a good education. He went to Paris and was influenced by the radical Communists he met. He went to China and met Mao at the height of the Cultural Revolution, when Mao was persecuting teachers and other educated people and sending them to the countryside to force them to work as  peasants. When PolPot took power in 1975, he drove everyone out of the cities within days by warning that American B-52s were about to bomb then. The cities were completely empty. Then he began a systematic campaign to wipe out every vestige of modernity. He killed between 1/3 and 1/4 of the entire population between 1975 and 1979.

Cambodians are a Buddhist people. Thousands of Buddhist monks were executed. Pol Pot was a madman but he found followers to do his bidding. He killed most of his top advisors , convinced that they were conspiring against him.

How does a country recover from a tragedy of this magnitude? As our guide explained, people with any education taught those with less. Those with a twelfth grade education taught thise with an 11th or 10th grade education. So on down the line. Those with only a sixth grade education taught the youngest children. And that s how the next generation was educated in a country where most of the teachers were killed.

There was no punishment for Pol Pot or his henchmen. In his paranoia, he sent troops into Vietnam, convinced that Vietnam was conspiring against him. The Vietnamese retaliated and deposed him. He died of natural causes while hiding out in the jungle in Thailand.

Cambodia decided not to prosecute the mass murderers. They wanted reconciliation,  or retribution. No one was punished for the mass murders of more than a million people.

The crimes of the Pol Pot regime are acknowledged.  There is no denial or obfuscation. Just a stark reminder of brutality and madness.

Our tour guide’s family did not suffer. They were poor farmers, Pol Pot’s ideal. But he hates Pol Pot, and he hates Communism, which he associates with mass murder.