In the duel of King Holiday weekend speeches, there is no question that Barack Obama won.

Indeed, on Sunday, he delivered the finest speech of a campaign that has heard the senator from Illinois deliver many fine speeches.

Obama did so by talking about deficits.

No, he did not return to the horrible, managerial language of the Clinton era, which tried to make the mere business of paying bills and balancing accounts into some sort of moral mission for the Democratic Party.

Nor did he simply deliver the kitchen-table economics address that he can and will master — with a few loans from John Edwards — if he is intent upon winning the Democratic nomination and the presidency.

Rather, in his Sunday speech at the Rev. Martin Luther King Jr’s Ebenezer Baptist Church in Atlanta, Barack Obama went to a higher ground — to that mountaintop that King occupied until his death on April 4, 1968, and that Bobby Kennedy stood for a brief and remarkable political moment that played out between April and June of that fateful year.

“Unity is the great need of the hour – the great need of this hour. Not because it sounds pleasant or because it makes us feel good, but because it’s the only way we can overcome the essential deficit that exists in this country,” Obama told a audience that hung on the every word of the most emotionally-effective orator to seek the presidency since Kennedy.

“I’m not talking about a budget deficit. I’m not talking about a trade deficit. I’m not talking about a deficit of good ideas or new plans,” explained Obama. “I’m talking about a moral deficit. I’m talking about an empathy deficit. I’m taking about an inability to recognize ourselves in one another; to understand that we are our brother’s keeper; we are our sister’s keeper; that, in the words of Dr. King, we are all tied together in a single garment of destiny.”

Obama used this notion of a deeper and more fundamentally-damaging deficit to frame the message of a campaign that is only now beginning to distinguish itself not just from the failures of the Bush era, with its immoral embrace of the economics of inequality and imbalance, but of the Clinton era, with its adherence to a technocratic economic vision that while sounder than Bushism still treated moral concerns as footnotes to a broader project.

Of course, it is appropriate to balance budgets. But there is nothing appropriate or moral about balancing what are at their root statements about our values — for what else can a budget that by its very nature picks winners and losers be? — on the backs of the poor.

“We have an empathy deficit when we’re still sending our children down corridors of shame – schools in the forgotten corners of America where the color of your skin still affects the content of your education,” said Obama, who continued:

“We have a deficit when CEOs are making more in ten minutes than some workers make in ten months; when families lose their homes so that lenders make a profit; when mothers can’t afford a doctor when their children get sick.

“We have a deficit in this country when there is Scooter Libby justice for some and Jena justice for others; when our children see nooses hanging from a schoolyard tree today, in the present, in the twenty-first century.

“We have a deficit when homeless veterans sleep on the streets of our cities; when innocents are slaughtered in the deserts of Darfur; when young Americans serve tour after tour of duty in a war that should’ve never been authorized and never been waged.

“And we have a deficit when it takes a breach in our levees to reveal a breach in our compassion; when it takes a terrible storm to reveal the hungry that God calls on us to feed; the sick He calls on us to care for; the least of these He commands that we treat as our own.

“So we have a deficit to close. We have walls – barriers to justice and equality – that must come down. And to do this, we know that unity is the great need of this hour.”

It will take more than just interest-rate shifts or macro-economic strategies to close the “empathy deficit.”

And, to his immense credit, Obama recognizes this.

“Unfortunately, all too often when we talk about unity in this country, we’ve come to believe that it can be purchased on the cheap,” the senator says. “We’ve come to believe that racial reconciliation can come easily — that it’s just a matter of a few ignorant people trapped in the prejudices of the past, and that if the demagogues and those who exploit our racial divisions will simply go away, then all our problems would be solved. All too often, we seek to ignore the profound institutional barriers that stand in the way of ensuring opportunity for all children, or decent jobs for all people, or health care for those who are sick. We long for unity, but are unwilling to pay the price. But of course, true unity cannot be so easily won. It starts with a change in attitudes – a broadening of our minds, and a broadening of our hearts.”

The call for “a broadening of hearts” is more than just rhetoric. It is a practical necessity. Obama can win the Democratic nomination and the presidency only if voters make a great leap. It is not a strategic leap. It is an emotional leap — motivated by faith and hope rather than compromise or cold calculation. To inspire it, Obama must avoid the pits and valleys of those squabbles into which the Clintons seek to draw him. That is the petty politics of the past, the politics that cost him a win in Nevada and could well cost him the nomination.

Instead of arguing about who closed which casino door in Las Vegas or who said what on a radio ad, Obama should be shouting from the mountaintops about this “empathy deficit” and about our ability to leap across it if we make the right choices.

This is the speech Obama has needed to deliver.

This is the speech America has been waiting for since that awful and glorious spring of 1968.

Barack Obama has found the language for a politics that transforms rather than merely transitions. He should not retreat from the mountaintop. He should hold the rhetorical ground he has finally captured, and call us to join him upon it.