Four years ago, as Barack Obama took the oath of office, the economic world was collapsing all around him. On Monday, he began a second term in a more stabilized economy but amid a political environment — and nation — paralyzed by deep ideological divisions.

His response was to offer an eloquent inaugural address that laid out an ambitious legislative agenda and sent a strong message — that despite the stalemate, he is not going to waste his renewed voter mandate. And he is ready to fight to see more accomplished in Washington.

"For now decisions are upon us and we cannot afford delay," he said. "We cannot mistake absolutism for principle, or substitute spectacle for politics, or treat name-calling as reasoned debate. We must act .<TH>.<TH>."

He stood in defense of entitlement programs, saying "the commitments we make to each other through Medicare and Medicaid and Social Security, these things do not sap our initiative, they strengthen us. They do not make us a nation of takers; they free us to take the risks that make this country great."

He made a strong push for more action in confronting climate change, noting that "the failure to do so would betray our children and future generations."

"Some may still deny the overwhelming judgment of science," he said, "but none can avoid the devastating impact of raging fires and crippling drought and more powerful storms."

He called for immigration reform, saying the nation needs to find "a better way" to welcome immigrants and to ensure "bright young students and engineers are enlisted in our workforce rather than expelled from our country."

And he made history by becoming the first president to mention gay rights in an inaugural address, in anticipation of what surely will be a major U.S. Supreme Court decision on gay marriage in the coming months. "Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law," he said. "For if we are truly created equal, then surely the love we commit to one another must be equal as well."

Overall, it was a hopeful address, memorable for both its ambition and conviction. Progressive and moderate Democrats alike can take hope that those things they wished Obama had championed during his first term may yet be accomplished. Conservative Republicans, on the other hand, who were hoping to continue stonewalling the president for another four years — much as was the case during the first term — should take his inaugural address to mean it's time to move past the politics of old. If not, they will have a battle on their hands.

The nation can take comfort in that. There are some things that are worth fighting for, and the president did a good job of identifying them on Monday — another landmark day in the life of our nation and our 44th president.