Not since the day almost 45 years ago, when word reached Washington that his brother, John, had been cut down in Dallas, has there been news about an individual that struck so deep a blow to so many in this capital. The medical bulletin from Massachusetts General Hospital about Sen. Ted Kennedy was at once a personal tragedy and a political cataclysm.
In his 46 years in the Senate, Kennedy has probably touched more people, in more cherished ways, than any other public figure. And his illness threatens to alter, for the worse, the prospects of every other politician - starting with Barack Obama and John McCain.
Like countless others, I have witnessed over the years the kindnesses Kennedy lavished on colleagues and friends - and even casual acquaintances. It was decades ago when another senator told me that, in complete privacy, Kennedy was sitting for hours with Sen. Philip Hart of Michigan, who had an illness that made him irascible and difficult to manage. Somehow, Kennedy calmed him.
When my beloved friend Mary McGrory, the great columnist at the Washington Star and Washington Post, had a stroke that left her almost robbed of speech, Kennedy and his wife continued to visit her, as before, drinking a glass of wine and regaling her with stories. At Christmas season, he brought along a piano-playing friend and sang Irish ballads for her.
Somehow in his more-than-busy life, he always seemed to be able to find time for those personal touches - and to perform them without seeming to realize how much they meant to the recipients. Their affection and gratitude were all but overwhelming on Tuesday.
But after the first shock at the news began to wear off, the sense kept growing that this was truly a landmark event in the nation's politics and government.
To a person, the men and women who share the responsibility of governing with him fervently hope that the prognosis implied by the words "malignant brain tumor" is not as ominous as it sounds.
But they have to reckon with the possible alterations in politics and government if Kennedy is sidelined for any period of time.
Kennedy has been the most respected Democratic senator for so long that no one comes close to his influence. He has also been one of the most energetic, always prodding and pushing his colleagues, undiverted by any other political ambitions or concerns since his one presidential campaign ended in 1980.
On issue after issue, but particularly on civil rights, health care, labor law, Vietnam and Iraq, Kennedy has set the direction for his party and mobilized the necessary support.
Even when the cause seemed lost, that bullhorn voice summoned Democrats to battle - and more often than seemed plausible, they achieved at least some of their goals.
He is clearly eager to play that role for Barack Obama, his choice for the nomination. Obama will search far and wide to find another Senate ally as committed and capable.
But it may still be true that McCain would find Kennedy's absence even more of a handicap than would Obama. It is doubtful that anyone could name another Democrat more willing to become a partner for the Republican nominee than Kennedy.
It is not simply that those two have legislated together on health care, immigration, campaign finance and ethics laws. Equally important, Kennedy consistently has searched for compromises that can bring Republican votes - as he did for President Bush on education reform. And at 76, he is far less inclined to seek partisan victories that poison the legislative well.
Truly, there is no one like him.
E-mail nationally syndicated columnist David Broder at email@example.com.