40 years after those 6.9 seconds in Dallas

Forty years ago today, John F. Kennedy was assassinated. Anyone much over 45 remembers hearing the news and the absolute shock of it. How to describe to anyone much under 45 what that experience was like? The obvious comparison is with Sept. 11, 2001 -- except for this difference. Before 9/11, there had been the Kennedy assassination. Before the Kennedy assassination, there had been nothing.

There has been calamitous news throughout our history: natural disasters, untimely deaths, military defeats (What could be more shocking than Pearl Harbor?). Kennedy's death was not even the first presidential assassination, and Lincoln's was more momentous.

It was, however, the first event of such overwhelming significance to be experienced nationwide on television. Only two months before, "The CBS Evening News" had expanded to 30 minutes. If Vietnam would become the nation's first living-room war, the Kennedy assassination became its first living-room death. More would follow -- Martin Luther King Jr.'s, Robert F. Kennedy's -- but as the poet Dylan Thomas wrote of the London Blitz, "After the first death, there is no other."

The Kennedy assassination wasn't just those 6.9 seconds of gunfire on that sunny afternoon. It was the national experience of collective grief over that weekend. It was seeing on television his alleged assassin, Lee Harvey Oswald, being gunned down on Sunday. It was the funeral on Monday, with the black-veiled widow, the two fatherless children, the foreign leaders seeming no less stunned than the average television viewer.

And there were the ways the assassination would not go away, how it kept expanding in the imagination. A vocabulary that had to absorb "Dealey Plaza" and "Texas Book Depository" soon needed room for "Zapruder film," "Warren Commission," and "grassy knoll."

Whether there was a conspiracy to murder Kennedy would come to matter less than the eagerness of so many to seize upon the possibility. It was a way of making sense of something that seemed so senseless.

Forty years is a long time in the life of a nation that began just 227 years ago. Yet for many, even many not yet born in 1963, the assassination doesn't seem far away at all. At least in part, that's because 40 years isn't so long a time when measured against such things as beauty and youth, chance and mortality. The death of John F. Kennedy was as much about those things as it was about America, and never have those things and America so precisely collided as they did in Dallas on Nov. 22, 1963.

Mark Feeney can be reached at mfeeney@globe.com.