We may be experiencing this week one of those pregnant moments that years later we look back on as history, amazed that at the time we didn't recognize it more for what it was. I am referring to this week's visit by Soviet President Mikhail Gorbachev to the United States. His speech to the U.N., coupled with his meeting President Reagan and President-elect Bush, seem unprecedented. So I wonder, how will these events appear with the hindsight of history?

A month ago I stood on a sidewalk in the heart of Moscow with earmuffs protecting my ears from the sharp night air of an approaching Russian winter. Just the day before, the first snowfall of the season had covered the city with a thin veil of white, and remnants of it earlier in the evening had turned the broad plaza of Marx Prospect into a mirror, reflecting the lights of the city off the broad expanse of wet asphalt in a glistening display.It was near midnight so there were few people in the streets, mainly policemen (more than usual, it seemed) in their long, gray winter coats with red trim and gray rabbit-fur hats. There were soldiers, too, on communications trucks. I had noticed them earlier that afternoon along the curb where the Intourist buses usually park. Young soldiers had been hooking up wires from communications trucks to utility poles, and I had wondered at the time what they were doing.

An hour earlier, when we had emerged from the Metro in front of our hotel, we were confronted by streets jammed with military hardware. Suddenly, it dawned on me:

This must be in preparation for the big parade.

Next week would be the 7th of November, the birthday of the Revolution, when the Winter Palace in Leningrad had been stormed in 1917 and the old order thrown out of power. Their "Fourth of July" is a day when, by tradition, surges of military prowess are paraded through Red Square and Soviet leaders stand along the top of Lenin's Tomb to review the troops. Years of cold war have burnt this image of the Soviet Union into our minds as an ominous stereotype. It was odd to suddenly find myself behind the scenes of its production.

This nocturnal practice session had obviously been staged because of the light midnight traffic when taxis and buses easily could be diverted away from the area around Red Square. Precise formations of tanks and armored personnel carriers lined Gorki Street in front of our hotel. Four abreast, they sat waiting, as far as you could see, filling the street from curb to curb, the sound of their idling engines producing a low, rumbling echo off surrounding buildings. Each had a driver wearing a leather pilot hat with chin strap and head phones. At the end of each column were jeeps with bright red flags on long antennas and coveys of restless officers sitting in them or standing by them exercising cramped legs.

It seemed they waited for the longest time. A small group of soldiers standing by a parked personnel carrier next to us was taking a smoke break. I studied them closely. They were only kids, really, some of them away from home probably for the first time in their lives. It was as though they were playing war and the tanks were the toys and the uniforms were all dress-up costumes.

Finally the signal came, and in no time the whole column was moving forward. After the personnel carriers and tanks came the rocket launchers, their rubber treads rippling the pavement like the amplified sound of a thumbnail rubbed across corduroy. And finally the huge missiles, white 30-foot shafts of weight and power, orchestrated out of side streets and thundering past on massive rubber tires. These were the missiles I had known since childhood, aimed in my mind's eye at Washington, Minneapolis, Salt Lake City and Seattle.

Then as suddenly as they had appeared, they had passed, disappearing as a ribbon of red tail lights and dim grumbling noise across Marx Prospect and up the little rise on both sides of the history museum into Red Square. They passed the GUM department store, splitting again to go around both sides of St. Basil's Cathedral and toward the river, where the sounds became fainter and fainter, and, then, in a moment they were gone.

Standing there in the stillness, I watched a lonely taxi zip into the Marx Prospect from one side, like a little puppy hustling from cover. It came nearer and nearer, speeding up as it came, and then it passed with the quick hiss of tires on wet pavement. Coming toward me from the right were two young couples locked arm in arm. As they passed, the sound of their voices, talking and laughing in indiscernible Russian tones were like mellow music. They turned and went through the park. As they disappeared into the darkness I felt the night progressing toward a calmness that seemed very sensible, human, hopeful and warm.

Similar feelings have surfaced again this week. In light of the political thaws that have begun to occur in recent months, they are feelings I almost dare nurture.