President Obama's supporters sometimes wonder where the inspirational candidate of 2008 has gone. The answer is to the White House. Obama's presidency is about smaller, less inspiring questions than his 2008 campaign.

Obama's presidency is bounded by the limits of the office and the demands of the moment. It is about what America needs to do right now — the next budget, the next bill, next year's taxes, the last war. Candidates can muse. Presidents must govern.

Obama's 2008 campaign was about what kind of country America is; how to read its past to best guide its future. His speech in Selma — which is really worth reading in its entirety — was among the best of his presidency precisely because it had almost nothing to do with his presidency; it was a return to the central topic of his campaign.

Historians who want to understand Obama will find few better summations than the two paragraphs at the core of this speech:

We do a disservice to the cause of justice by intimating that bias and discrimination are immutable, or that racial division is inherent to America. If you think nothing's changed in the past fifty years, ask somebody who lived through the Selma or Chicago or L.A. of the Fifties. Ask the female CEO who once might have been assigned to the secretarial pool if nothing's changed. Ask your gay friend if it's easier to be out and proud in America now than it was thirty years ago. To deny this progress — our progress — would be to rob us of our own agency; our responsibility to do what we can to make America better. Of course, a more common mistake is to suggest that racism is banished, that the work that drew men and women to Selma is complete, and that whatever racial tensions remain are a consequence of those seeking to play the "race card" for their own purposes. We don't need the Ferguson report to know that's not true. We just need to open our eyes, and ears, and hearts, to know that this nation's racial history still casts its long shadow upon us. We know the march is not yet over, the race is not yet won, and that reaching that blessed destination where we are judged by the content of our character requires admitting as much.

Those 230 words are a precise distillation of Obama's view of America, and the role politics must play in it.

The first paragraph is Obama's case for hope: America is improving; it has always been improving, and to deny that improvement is to steal from Americans a belief in their country that they have more than earned. "To deny this progress — our progress — would be to rob us of our own agency," he said.

The second paragraph is Obama's case for change: America's sins are not vanquished; its hatreds remain real; its racism still breathes. "We know the march is not yet over," Obama said, "the race is not yet won, and that reaching that blessed destination where we are judged by the content of our character requires admitting as much."

Hope and change. These are the two ideas that form the steady core of Obama's politics. But, more than that, they are the two ideas that define, for Obama, what kind of country America is — and what it means to serve it.

Obama's critics question his love for the country he governs. "I do not believe — and I know this is a horrible thing to say — but I do not believe that the president loves America," former New York Mayor Rudy Giuliani said in February. They look at Obama's steady belief that America is not yet good enough, not yet pure enough, not yet perfect enough, and they see a skeptic, not a patriot.

In this speech, Obama's answer to this criticism was direct:

Fellow marchers, so much has changed in fifty years. We've endured war, and fashioned peace. We've seen technological wonders that touch every aspect of our lives, and take for granted convenience our parents might scarcely imagine. But what has not changed is the imperative of citizenship, that willingness of a 26 year-old deacon, or a Unitarian minister, or a young mother of five, to decide they loved this country so much that they'd risk everything to realize its promise. That's what it means to love America. That's what it means to believe in America. That's what it means when we say America is exceptional.

There is an implicit radicalism in what Obama is saying here. To believe America is good enough is to abandon the tradition of criticism and activism that has made America great.

Obama's answer to Giuliani is that Giuliani has mistaken uncritical adoration for the hard work required of true love. Patriotism is active, not passive. Those who love America prove it by working to perfect America. They continue marching.