The other day I went to visit some Russian friends at their dacha about 40 minutes' drive from Moscow. Though the weather was good, and we played tennis and swam and walked in the piney woods, my true purpose was to open an inquest.

I wanted to know what intelligent, sensitive Russians, who were not dissidents but did cherish many American values, thought about the recent deterioration of relations between the two countries. I wanted their explanation for the strange sickness, if not death, of detente.

Over lunch at a big family table served by a Lazy Susan, one of them, an economist, raised the subject for me. He said he was both "troubled and puzzled by the change in the atmosphere in relations between your country and mine. Our press and your press speak of Zbigniew Brzeziski. But I cannot believe only the adviser can be blamed."

He went on to say that he supposed President Carter must be responsible. "He is a small businessman, not a statesman. He has no clear purpose. Today he says one thing. Tomorrow the opposite. It is very hard to deal with him."

I remarked that since the illness of President Leonid Brezhnev the Russian leadership was not so easy to deal with either. Brezhnev talked detente, but various Soviet officials did things highly prejudicial to good relations. I cited the trial of two American newspapermen on charges of slander, the arrest of an American businessman, the harsh sentences meted out to Soviet dissidents and the trials of Alexander Ginzburg and Anatoly Scharansky.

Nobody bothered to assert that Brezhnev was in the pink, and I inferred that, for one reason or another, those responsible for internal security had recently gotten a greener light than in the past. But a woman doctor observed of the arrests and trials:

"Those things happen when relations between our countries are tense. You think you can press us to the wall, and read us lectures on how to behave in the field of human rights. But the Russian people are a proud people - proud of their story and proud of their achievements. When you insult us and tell us how to behave, there will be trouble."

I said that many Americans felt the Russians had compromised the spirit of detente by increasing Soviet influence at American expense in distant parts of the world. I mentioned coups in Afghanistan and Yemen. And the large Soviet and Cuban presence in Ethiopia and Angola. My host, a physicist, laughed.

"In the past," he said, "we also made what you called 'gains.' We were invited into Egypt, Syria, Iraq, even China. Then we were invited out. That's how it will always be. So none of these events are important enough to justify tension between two countries that could blow up the world."

When lunch was over, I said that since I had flown from Tokyo the previous day, I was tired and would like to take a nap. "We have debated that," the physicist said in the heavily humorous way the Russians have, "and we agree that there is a human right to take a nap. But we will wake you in exactly one hour for tennis. Punctuality is said to be the courtesy of kings, but just because the revolution ended the monarchy, that does not entitle us to be late all the time."

In fact they let me sleep for three hours. But I reverted to the punctuality remark later. I said that many Americans felt the great Russian difficulty was an economy that offered no incentives for people to work hard or be on time or develop new products and services. If Russia was up against the wall it was because of the economy, not the American campaign on human rights. "You've cornered yourselves."

I asked the economist what he would say if he were Brezhnev and had to give a speech on the economy. He replied, "I would say that people should work harder and be more diligent."

"And what would be the people's response?" I asked. He did not answer, so I said: 'They would laugh." He nodded.

"It is true," the physicist then said, "that there are great differences between our countries. But that is all the more reason to hold tightly to the few areas of cooperation. It is so hard to build them up, so easy for them to crumble."