Change is in the air this political season -- in the ever-increasing likelihood that an African American will stand as the Democratic nominee for the presidency, and in the near-certainty that Edward M. Kennedy of Massachusetts, the Senate's liberal lion, soon will exit the institution he has bestrode like a colossus for nearly 50 years.

Just as Barack Obama's primary victories remind us that change often goes hand in hand with progress, so the sudden news of Kennedy's illness is a somber reminder that change also is inevitably loss. Call it tragic wisdom.

Watching the outpouring of emotion from both sides of the aisle Tuesday at the news of Kennedy's condition, it was clear that his senatorial colleagues already are stricken by his impending departure. Partly, of course, that's because Kennedy's tenure in that chamber spans one of the most tumultuous eras in this nation's history. He will exit the Senate as its third-longest-serving member ever. When he first took his seat in 1962, Jim Crow and its de facto shadow were a fact of American life, and women's rights barely extended beyond the franchise. This year, Kennedy enthusiastically endorsed and campaigned for Obama in his contest against Hillary Rodham Clinton.

A new world, surely, and one he helped usher in. But also one that seems to be unfolding without three qualities that distinguished Kennedy's long service.

The first is empathy. It's shocking just how tenuous belief in the possibility of empathy as a public emotion has become. Kennedy's brother, Bobby, was fond of quoting the ancient Greeks. One of them, Thucydides, once was asked, "When will there be justice in Athens?" He replied, "There will be justice in Athens when those who are not injured are as outraged as those who are."

If Ted Kennedy's 46 years in the Senate have stood for anything, it is for the enduring power of that antique insight. He is a rich, wonderfully connected Boston Irishman, and yet his life's labors have been on behalf of blacks and women and Latinos, for people who sweated for a minimum wage and couldn't pay their sick child's doctor's bill and asked for nothing more than a public school good enough to give their child a fair foothold on the ladder's next rung. Their slights and injuries were his own.

Today, increasing numbers of Americans and their politicians are lost to narcissism and its communal expression -- identity politics. We believe that no one can feel our pain but us, and we care for none outside our tribe. Kennedy's career has been a half-century reproach to that crabbed notion of the American condition. He believed unshakably in solidarity and the common good, and if that now seems quaint, the fault -- and the loss -- is ours and not his.

Child of privilege that he undoubtedly was, Kennedy also stood for a second quality that is fading: the belief that after the accumulation of wealth came an ambition -- indeed, an obligation -- for public service. It's a notion this new Gilded Age finds slightly ridiculous, but not long ago we expected our national leaders to amass their fortunes before taking office and not during or immediately after. There is a meanness of spirit to an age that commoditizes elective office into an economic opportunity.

Finally, one of the reasons Kennedy's Senate comrades will feel his departure so acutely is that he always stood for a civil partisanship. There was no more committed liberal Democrat in that chamber.

A struggle with Kennedy was a bare-knuckle fight to the finish, but always according to traditional politics' version of the Marquess of Queensberry Rules. It was never personal, and differences never precluded friendship, which is why the senior Massachusetts senator could work with George Bush or John McCain or Orrin Hatch, and will leave office with a record as one of the most effective lawmakers of all time. Nothing deforms our contemporary politics in quite the way the loss of Kennedy's old-fashioned civility does.

In his recently published memoir, Ted Sorensen, John Kennedy's special counselor, recalled how the president secretly dispatched him, along with Bobby, to assist his youngest sibling in his first run for the Senate. Teddy's opponent was the favorite nephew of Democratic House Speaker John McCormack, whose help JFK desperately needed, so it was necessary to maintain fictional neutrality.

Sorensen thought Teddy a callow candidate. But his brothers' murders and personal tragedy changed that. For a time, it seemed he might become an American Parnell, a leader of vision and skill undone by personal appetites. That too was surmounted. Today, Sorensen judges him thus: "More respected and effective today than some presidents have been, Ted long ago came to terms with the fact that he need not be president to fulfill his portion of the Kennedy legacy. ... I think he will ultimately die in the Senate. More active and at home in that body than either of his brothers, Ted was -- and still is -- the most relaxed campaigner of the three, with an easier style on the public platform, the best politician, better able to work with other senators in both parties.

"Always the liberal lion, he has proven to be a courageous battler on the cutting edge of issues both domestic and foreign, maintaining the liberal tradition of his brothers, even when others in the Democratic Party showed less courage. ... Jack and Bobby would have been proud."