It was Sunday morning. The Americans woke up, brushed their teeth, weighed themselves, made a pot of coffee and opened the paper. Forty-six Marines, said the early report, had been killed in Beirut.

The Americans went through their day, carrying dismay in their back pocket. They pulled it out and looked at it as they raked leaves and made dinner and did the laundry. By the evening news, the count was 140.

On Monday morning, they got dressed for work and school in the October morning darkness, and found out that 161 Marines were dead. On Tuesday morning, they put orange juice on the grocery list and defrosted something for dinner and scrounged up enough money for gas, and the count was 207, then 214. On the way to work there was an odd sun shower and a rainbow over the expressway and the car radio told them that Marines had landed in Grenada. Two were dead.

All week, in between commercials and chores, they saw the televised pictures of boys, forgive me, men, but such young, young men who died in Lebanon. The 19- year-old who wanted to be a Marine captain. The 20-year-old who wanted to come home for Christmas.

There were also words from the families of Marines. The Florida father who was proud that his son died for his country. The Chicago mother who was still waiting for word from Lebanon and asked with bewilderment, "In the first place, what are they doing there?"

In Washington, the men who have to answer such questions put on their ties and suits and serious voices. They talked about the difficulty of getting out of one situation and about the rationale for getting into another. They talked about vital interests, and loss of credibility and toughness.

Behind all these worldly bulletins of dismay and confusion and despair, one word recurred like some subliminal message: Vietnam . . . Vietnam . . . another Vietnam. It echoed in the halls of Congress. It appeared in the photograph of a Marine in Beirut lying near the disaster site reading a book called "Nam." It permeated the atmosphere at Dover, Del., where they awaited the bodies from Lebanon--bodies that used to come there from Saigon.

Does history repeat itself like this? Not so neatly, I'm afraid. The president sees Munich Treaties and Pearl Harbors in every conflict. My own contemporaries see Tonkin Resolutions and Haiphong Harbors everywhere.

But Lebanon isn't another Vietnam, nor is Grenada. They have only one thing in common with that country in Southeast Asia: us. When we use the word Vietnam, we are not talking about another country, but about our own experience.

To us, Vietnam was a war that barely interrupted life and yet totally disrupted it. Those of us who are not veterans or the families of veterans were not called upon to sacrifice so much as a pad of butter or a pair of nylon stockings for the cause. In theory, our daily lives went on the way they went on this week. We made meals and changed diapers and took out garbage and paid bills. While other people died.

But Vietnam was the first war that we saw, really saw. If one thing changed war forever it was the television lens. At night, when the dishes were done, we saw the body bags of people who had died while we were eating lunch. On the weekend, when the football game was over, we saw other mothers asking,"Why?"

There are some who say that our ability to protect ourselves from the direct effects of the war prolonged it. The shells didn't hit our streets. But cameras penetrated every shield.

During Vietnam, at some point, it became impossible to sit eating dinner off TV tables while Charlie Company died. At some point, it became unconscionable to go about our daily lives while the death count went up and up and up. The gap between our own easy lives and the grisly toll of young soldiers grew into a black hole that sucked in everything.

Wars are not edited and cleaned up with glory copy any more. They come bloody, into the middle of our days. We are there within moments. It takes the surest goals, the purest motives to counterbalance one picture of a line of coffins. No politician's bluster can answer one mother's question, "In the first place, what are they doing there?"

This then, is what we call "another Vietnam." Another war watched from the sofa. Daily life chafing against daily death. The politician who cannot read the real "Vietnam" message in the week's news deserves T. S. Eliot's sad epitaph: "We had the experience but missed the meaning."