I still don't know exactly what it was I saw that afternoon on Canton's busy Chungshan Street. A large crowd blocked traffic. Two men held the arms of a third man. The captive struggled and grimaced. All three disappeared into the crowd.

The only foreigner within sight, I backed up against a wall where I could see without being seen. One of the men appeared again. Standing on something, he took pieces of what looked like twine out of his belt and dropped them down to someone below. The crowd began to move down the street. I could see the two men wheeling away a bicycle with a sidecar holding the third man, apparently bound hand and foot.

Here it was my first full day in China, and I had a mystery I could not solve. After years of studying China's history and language but never having visited the place. I began to appreciate the difficulties of being a lone foreign fish in a vast Chinese sea.

What clues did I have? A girl in the crowd had giggled. Two uniformed soldiers looked on but did not interfere. The three men in the struggle all wore standard, faded gray work clothes. No policemen had appeared, although one was posted at a nearby corner. I tried to ask a bystander a question, but got only a nervous smile in return.

Was it a citizens' arrest of a bicycle thief?

A skirmish between political factions? Hospital orderlies apprehending a mental patient? A family squabble? Street theater? I don't know.

During a 14-day, 3,500-mile trip through the People's Republic of China, I was often impressed at how much the Chinese, always suspicious of Western journalists, were willing to show and tell. Official guides took us to theaters, factories, farms, private homes and even into the inner sanctum of the Foreign Ministry for an interview with a senior official. I always had a couple of afternoons or evenings in each city to walk the streets without escort and read wall-posters.

Perhaps the Chinese officials realized that there wasn't much out there for me to see. The wall-posters with lurid charges and counter-charges seen often last year were mostly gone. A big pre-May Day cleanup was on, and most of the remaining posters heralded the publication of the fifth volume of Mao Tze-Tung's selected works.

With much of the political juice squeezed out of Chinese street life, a visitor could concentrate on the background noise and humor. Taxi-drivers cursed one another. Office workers made loud use of spittoons placed everywhere. A young boy carrying manure out to a commune cornfield tossed some into the hair of his sister. Then ran away laughing. Soldiers joked loudly about their squad leader as he struggled with a portable earth-turning machine.

I received some stares and my wife, eight months pregnant, received even more. But we could go up to store counters to buy gifts or ask directions from a passerby without much commition.

On our scheduled visits to factories and farms, we were treated to official kindnesses we had never before encountered as journalists. At each stop was a large blackboard labeled "Warmly Welcome" with a much-erased spot in the middle where someone had chalked in "American Friends" in Chinese.

Peking had not granted any visas to American journalists writing regularly about China since Mao's death last September, so I asked why I was so favored."Well, Mr. Mathews," they said, "you have written us so many times." In Hua Kuo-feng's China, worker diligence wins the highest praise, and perhaps that now applies to foreigners seeking visas.

Some of our requests were turned down, usually on the ground of limited time. There had been many reports of a fall off in Chinese steel production, so we asked to visit a steel plant, but had no luck. We failed in attempts to interview an expert on national economic planning or to visit an earthquake shelter.

Numerous briefings on the crimes of the disgraced "Gang of Four" provided insights on political life in China, and we switched guides often enough to check some odd stories.

One guide had told us the metal shutters on Shanghai shops were simply vestiges of the high-crime years before 1949. When my wife asked another guide about them, she was told that they were necessary to keep out burglars in 1977.

I asked officials of the research institute at the model commune of Tachai why they had no picture of Chairman Hua in their reception room. They paused, laughed, then paused again. Finally the senior man said the only picture they had managed to acquire so far was in the main reception room upstairs.

One night in Peking, I tried to pierce some veils by joining the young people strolling about Tienanmen Square. With a blue sweater, blue slacks and one of the ubiquitous blue worker's caps on my head. I could pass for a Chinese in the dark. The Peking dialect of Mandarin Chinese is the only one taught by most American universities and the only one I can readily understand, so I decided I would not be eavesdropping, but just having a language exercise.

A sample of the conversations that night: First Girl: "What are you doing on May Day?" Second Girld: "I don't know, how about you?"

First Boy: "And then the teacher said the exercise would be due tomorrow." Second Boy: "Oh, my."

Young Woman: "How much did you spend for dinner?" Soldier: "About $20." Young Woman: "Too much."

Perhaps I didn't learn much more about China, but for a while I felt at home.