This was not supposed to be as big a moment as the last one. President Obama’s second inaugural would be witnessed by a smaller crowd than his first. It would not be as historic because it would only be the second time an African American took the presidential oath, not the first.

And the speech, coming as it did after four divisive years of partisan battling and a tough re-election campaign, would not carry the same emotional message of hope. Gridlock is not going away, and the optimistic idea that we can all work together to solve our collective problems seems hopelessly naive.

Well, the crowd might have been smaller, but it was still huge. And even though we have already seen an African American take the oath, a black president standing on the steps of a building made with slave labor — on the day we celebrate the memory of a civil rights leader who gave his life for a moment like this — is still historic.

The president’s hair may be grayer than it was in 2008, and he may have been bruised in the political back-and-forth of the past four years, but his formulation that no problem is too great for our country when we work together is still a powerful message of hope for our future.

There is a change of tone this time around. This President Obama is not asking a divided nation to stop fighting, but he is not satisfied to fight to a draw.

“For now decisions are upon us and we cannot afford to delay. We cannot mistake absolutism for principle, or substitute spectacle for politics or treat name-calling as reasoned debate. We must act, knowing that our work will be imperfect. We must act, knowing that today’s victories will be only partial and that it will be up to those who stand here in four years and 40 years and 400 years hence” to complete them.

This message may be less hopeful, but it’s more realistic and mature than the rhetoric of 2008.

It welcomes the fight ahead, connecting the debates over gay rights, climate change and immigration reform with the great battles of the past that ended slavery, won women the vote and gave full rights of citizenship to all Americans.

It’s important to remember that Martin Luther King Jr., whose birthday was celebrated Monday as a national holiday, was a controversial figure during his lifetime, one known as much for his militancy then as he is known for his dream of unity today.

The big issues we face are not going to disappear in a cloud of consensus. Obama is right to hope, but he is also right to be ready to lead the fight.