Traveling on the Trans-Siberian Express

How far we are from Europe!'' sighs a character in Tolstoy's play ''The Fruits of Enlightenment.'' But to a traveler who has just spent five and a half days coming from Asia on the Peking-Ulan Bator-Moscow train, one's first impression of the capital of world communism is that this is, indeed, a rather splendid European city.

I hasten to add that this is not a political judgment but a visual impression. Contrasts between Peking and Moscow, Asia and Europe, are as piquant as the abrupt change in dining cars from sauteed prawn and bamboo shoots to borsch and beef stroganoff. But the mental dimension is more elusive. What is the essence of Europe? Of Asia?

One may wrestle with such problems as one's train rumbles comfortably across the Mongolian grasslands or traverses the thick forests of Siberia. One can also revel in escaping, for the space of five and a half days, the tyranny of time and routine. No newspapers, no broadcasts except of train times, but memories of a Mongol colt, mane streaming, racing our train, or of Siberian peasant women at a station called Zima, shouting at us to buy their neat mounds of tomatoes, carrots, freshly picked berries, or pickled cucumbers.

A trip on the Trans-Siberian is the next best thing to a ship's cruise, and it is much cheaper - just 474.60 Renminbi or $237.30 at the current rate of exchange for a first-class one-way berth from Peking to Moscow via Ulan Bator.

My wife, college-age daughter, and I boarded our train early on a Wednesday morning. Our traveling companions were tourists from Europe, the United States, and Hong Kong, Chinese diplomats newly assigned to Yugoslavia, and - in the second-class compartments - backpacking students from all over the world.

Quietly, matter-of-factly, our diesel train pulled out of Peking's cavernous station at 7:40, bathed in the glow of the same sun that burnished bright the roof tiles of the Forbidden City. And just as quietly, just as matter-of-factly, the following Monday evening at 6:15 we rolled into Moscow's picturesque Yaroslavsky station.

Lao Dou and Lao Liu were our carriage attendants. Lean, quiet, quick, they kept our carriage spick-and-span inside and out. They had worked on the same train for 15 years and knew just about every tree and every stone along the way. ''In 10 minutes you can see the Great Wall,'' Lao Dou said, when we were barely an hour out of Peking. Or two days later, ''Lake Baikal will be on our right in about 40 minutes.'' And it was.

One of the most memorable moments of the trip came on the first night, when we had reached Erlian on the Sino-Mongol border and were waiting for the train's wheels to be changed from standard gauge to the wider Soviet gauge. This is a three-hour process.

During that time we strolled up and down the platform, enjoying the full moon. A long, low line of bluish hills extended to the horizon. Above them hung the clear, clean night sky. The moon lit up the silhouettes of freight trains standing still in their tracks, their engines occasionally sending up clouds of whooshing white. In the stillness of the night, these sleek black monsters with hissing breath, symbols of an age that in the West has passed into history, seemed almost animate beings.

We took a whole day, from midnight the first night to nearly midnight of the next, to cross Mongolia. Once the Mongols ruled both Russia and China. Today they form a nation of 2 million, a member of Comecon and of the Soviet bloc, with several Soviet divisions guarding their long frontier with China.

Our train stopped at Ulan Bator, Mongolia's capital, for half an hour. We tourists scampered off and across the huge, empty station square, past two huge portraits of Mongol Premier Tsedenbal and Soviet President Andropov. We had not gone more than 10 minutes down the broad avenue that leads away from the station before Mongol policemen with maroon shoulder tabs came running after us to herd us back to our train.

We reached the Soviet border at Naushki about 11:00 p.m. the same day. Two unsmiling young border guards in garrison caps and neatly pressed khaki uniforms strode down the corridor of our carriage, ceremoniously saluting before entering each compartment where passengers awaited them with passport, customs declaration, and visa in hand. The guards, with green or brown eyes and curly brown hair, were unmistakably European. Somehow it was startling to think that, as deep in Asia as we still were, we had already crossed an ethnic as well as a political frontier. From Naushki on, we were effectively in Europe.

Irkutsk, the first large Siberian city, occupies a handsome site on the broad Angara River flowing from Lake Baikal. Along with modern factories and office buildings, traditional wooden houses, their window frames decorated with painted Russian carvings, occasionally flash by. Irkutsk station itself bustles with activity. A train on a branch line stands on the other side of our platform, passengers crowding aboard with bicycles, knapsacks, and an occasional guitar. Are they off for an outing in the woods that surround the city? They look curiously at us, and we at them, but there is no contact.

Contact, for me, came much later, on the morning of our fifth day, at a small station called Ishim in western Siberia. It was a raw, misty morning, and as I walked briskly down the platform a voice said to me in Russian, ''Cold, isn't it?'' ''Yes,'' I replied rubbing my hands. We introduced ourselves, me trying furiously to dredge up Russian words imperfectly learned 15 years ago and now almost completely forgotten.

''Aram,'' said my new friend. The only response I could think of was ''Khachaturian?'' ''Nyet, nyet,'' Aram laughed, ''but I am Armenian.''

Aram visited us in our compartment some hours later. He was going from Novosibirsk, Siberia's largest city, to Perm, and would be back home with his wife and six-year-old son by the weekend. He had cousins in Los Angeles but felt most at home in Yerevan, capital of Armenia, where he had been born.

''But I am a trombonist, and there is no work for me in Yerevan, whereas the orchestra in Novosibirsk begged me to come. I get a good salary, 300 rubles a month. I teach at the conservatory. And I have become cultural director at a factory.

''No, I don't have a car yet. My first priority is to get a bigger apartment. I have just two rooms now, each not much bigger than this train compartment.

''In the US, does it take you long to get a passport? Here, I had to wait three months just to go on a group tour - a cruise - of the Mediterranean. Documents, documents. It was lucky I was just a trombonist, not an engineer with secrets - otherwise they'd never have let me go. Altogether there were 330 of us on the cruise ship from Odessa. Thirty of these were from Novosibirsk.

''Yes, I'd like to visit the US some day, but it's not so easy now. On my next trip, I'd like to see Japan. Such beautiful television sets, such wonderful stereos. I bought a Soviet color television for 600 rubles, and already I've spent the same amount in repairs. A Sony costs twice as much, but the minute our local department store gets a shipment, there is a huge queue and the whole supply is sold out in a few minutes.

''I'm glad we are talking with the Chinese again. The whole world needs peace. We lost 20 million lives in the war with Hitler, and no one here wants . . . war again.''

Ordinary words from an ordinary Soviet citizen. To me they were a reassuring reminder that, as a Chinese who had studied in America once said, ''Human beings are much the same the world over. We all have the same longings, we have much the same reactions. Only the systems we live under are different.''

Some time before Perm, Aram shook hands and left us. We exchanged addresses, promising to write each other. ''The next time you visit the Soviet Union, try to include Armenia in your itinerary,'' he said, ''and I will fly there to meet you.''

Our Trans-Siberian trip was rapidly drawing to a close. Long before Perm, we had crossed the Urals into Europe. I had been sitting with Lao Liu in his compartment, eager not to miss the slender obelisk that marks the boundary between the two continents. Lao Liu patiently counted every kilometer marker for me as it flashed by, and then, ''There!'' he pointed, and there it was - an inconspicuous monument on a grassy slope beside the tracks, a group of fair-haired children skipping around it.

When de Gaulle spoke grandly of Europe ''from the Atlantic to the Urals,'' the mountain ridge separating Europe from Asia seemed a portentous barrier. But along this stretch of railway, it is a gentle slope no steeper than the hills of Newton that so bedevil runners on the last stretch of the Boston marathon.

The political boundary between Europe and Asia lies on the Sino-Soviet border , or if one counts Mongolia as within the Soviet bloc, on the Sino-Mongolian border. In the sense in which Tolstoy used the term, however, Europe symbolizes a state of civilization, a state of consciousness. To the Westernizers of Tsarist Russia, their country was indeed far from Europe. Asia, too, has its equivalent of the Westernizer-Slavophile controversy of 19th-century Russia. The Chinese are Communist, but they talk of absorbing the science, the technology, and even the management methods of the West, while retaining their own Chinese spirit.

Still, Chinese or Russian, American or Japanese, we all share the same planet. The Urals, today only a barely distinguishable geographic line without political or ethnic significance, may someday stand as a symbol of the disappearance of other, man-made boundaries, much more rigid, much more formidable, separating system from system, people from people, you from me.