So if Obama’s Trayvon moment was not the debut of a new, more activist president, was it at least the beginning of a national conversation about race? If so, I doubt it will be a conversation led by the president. When race came up in an interview published in Sunday’s Times, he promptly segued into a discussion of economic strains on the social fabric.

And that’s O.K. President Obama has an economy to heal, a foreign policy to run, a daunting agenda blockaded by an intransigent opposition. Randall Kennedy, another Harvard law professor who has studied Obama and criticized him for a lack of audacity, says frustration should be tempered by realism. “My view of Obama is as a Jackie Robinson figure,” Kennedy told me. “Jackie Robinson breaks the color barrier and encounters all sorts of denigration, people spitting on him, and because he was a pioneer he had to be above it all. … People expect Obama now to all of a sudden jump into this totally messy issue of race and the administration of criminal justice? It’s completely implausible. To do it would require a major investment of political capital.”

And, come to think of it, why is that his special responsibility anyway?

“There’s sort of a persistent misperception that talking about race is black folk’s burden,” said Benjamin Jealous, president of the N.A.A.C.P., when I asked him about Obama’s obligation. “Ultimately, only men can end sexism, and only white people can end racism.”