There is a ritual that accompanies public death, a distinctly American science of public grieving and public reflection and public analysis. Public death has come to be defined as the tragic loss of those so famous or important or singular that their sudden departure triggers the ritual.

John F. Kennedy and Martin Luther King Jr. . . . Elvis and John Lennon . . . The astronauts of the space shuttle Challenger and the kids of Columbine High . . . Princess Di and now JFK Jr., whose body was retrieved from underwater plane wreckage and brought back to land yesterday.

"When you do have people of that magnitude, there is a kind of collective participation that takes place," says Gary Laderman, a professor of religion at Emory University and author of the book "The Sacred Remains: American Attitudes Toward Death, 1799-1883." He is now working on a 20th-century sequel.

"I don't want to overstate this," Laderman says, "but these things mark our history. They are like guideposts. They are moments of collective solidarity in a way that doesn't really happen in other areas of civic life. There is a kind of intimacy between the living and the dead."

Public death has become one of the binding American experiences, giving strangers something to talk about in a culture in which individuals are increasingly distanced. When George Washington died in 1799, there were independent funeral services with empty coffins in villages all over the country, attended by folks who never met Washington or each other but whose hopes for the nation were embodied in him.

"We are not a communal society in the way that we used to be," says Wanda Ruffin, an assistant professor of psychology at Hood College in Frederick, Md., who is working on a book on New Orleans jazz funerals and mourning. "We may not know our neighbor, but we know JFK Jr., so when he dies we want to be a part of that."

When Abraham Lincoln was assassinated in 1865, his body went on tour, carried on a funeral train to 20 cities, where hundreds of thousands of Americans lined up to bid their farewells. There was a need by the citizenry to overcome Lincoln's death, and embalming was the societal development that made the mass catharsis work. Embalming then became the foundation for the funeral industry, which created a "whole class of professionals," as Laderman puts it, "who based their expertise and mediating position in society on their ability to make the dead presentable so the living can get one last look."

Now, more than ever before, society's mediators are the media. The 20th century brought television, which broke new ground in 1963 with the exhaustive chronicling of the assassination of President Kennedy. Now there is 24-hour cable news and the Internet and more ways for Americans to absorb the deaths of the notable and plug into the ritual.

It begins with news anchors coming in on their off-days or flying to the scene to take command of the story for their networks, the first sign that the story is really important.

Saturation TV coverage follows, and when there are no new facts to report, "experts" fill the void. The experts are pushed to push the envelope. They offer theories on the circumstances and causes of death. They perform pop psychology on the victims. They explore the "larger lessons" for society. The search for metaphors is constant: It's like something out of "Macbeth" or "Richard III."

The public feeds off this commentary, and spontaneous debates erupt in office buildings and health clubs and living rooms, where people are keeping track of the latest developments and forming their own opinions. Did Kennedy's reckless urges finally do him in? Was the plane defective? What if he had left earlier in the evening, leaving more daylight for the flight?

Citizens rush to designated mourning sites--in this case so many sites: the John F. Kennedy Memorial on Cape Cod, the Kennedy Library in Boston, the Kennedy grave site at Arlington National Cemetery, the TriBeCa apartment building where John Kennedy Jr. and Carolyn Bessette Kennedy lived. They toss bouquets and cards, and they stare or they cry.

Ministers incorporate messages of healing in their church services. The tributes--and not particularly from the ministers--quickly turn to deification because that is also part of the American ritual, to go way, way over the top. As television critic Howard Rosenberg wrote in the Los Angeles Times, young Kennedy, like Princess Diana, "appears destined to be closely scrutinized, glorified and celebrated far more in death than in life when to most Americans he was less a widely beloved national figure--regardless of what you're hearing now--than a good-looking celebrity with a famous name."

Official grief must be expressed, and the intention here is to say something more profound than you're sorry, to express something more lasting than simple sympathy. Rep. Jesse Jackson Jr. (D-Ill.) spoke of the burdens of inherited fame, of needing to work "oftentimes twice as hard to show people that we are who we are, we're real people and we're trying our very best to make a difference." President Clinton spoke of the uncertainty of life itself.

"We are reminded again that life and its possibilities are fleeting," he said, "that we mortals are obliged to be humble and grateful for every day and to make the most of every day."

This is how we do it.

Then come the funerals and memorial services and the televised shots of solemnity--family members dressed in black, wearing dark glasses, dabbing their eyes. The TV narrators speak in hushed tones . In the case of Kennedy and his wife, Carolyn, whose body also was recovered yesterday, a private Mass is being planned for tomorrow morning at the Manhattan church where his late mother worshiped.

For those not invited to the services, modern technology is marvelous. It heightens the ability to grieve en masse. The Internet has become a giant Hallmark card. As of yesterday evening, more than 20,000 prayers and condolences for the Kennedys and the Bessettes had been posted on American Online message boards. And that is not the first time for this kind of thing. "In the case of Princess Di," says AOL spokeswoman Regina Lewis, "we printed them out and gave them to the family."

Dot Noseworthy, a 60-year-old retiree from New Hampshire, posted this note on the George magazine site through AOL: "All Americans have lost something very special and beautiful. The Kennedy family has endured more than their share of tragedies, but this one seems like the worst since the Sixties."

Later, she described by phone why she felt moved to respond that way. "You feel, because of the media coverage today, that you become a part of the event. And with John-John and Princess Di, they were in our lives a lot. With John-John especially we felt like he was one of our own."

She paused, took a breath, then broke down in sobs.

"Excuse me. You feel a need to express that. If it were a friend, you could pick up the phone or send a note, but in this sense AOL provides a platform. It's part of the process, you have to let your feelings out."

This is how we do it.

But why?

Maybe it's because public death has become for some a reference point for their own mortality.

"This kind of tragedy slows us down," says Ruffin, the Hood College professor. "It allows us to meet some of the needs that go unmet in our day-to-day lives. At the blink of an eye, I could be gone. What does this life really mean? It helps us to address our life again."

And in a world in which unimaginable acts keep happening, the ritual accompanying public death provides a vehicle for making sense of the senseless. As a result, 20 years from now some will remember where they were when they learned John F. Kennedy Jr.'s plane went down, Life magazine will print another Kennedy anniversary issue and some network television special will do a retrospective and show all over again those same pictures of little 3-year-old John-John saluting his father's casket.

Staff writer Richard Leiby contributed to this report.

CAPTION: A makeshift memorial at the entrance to John F. Kennedy Jr. and Carolyn Bessette Kennedy's apartment in New York.