We may be reaching an inflection point, the moment when the terms of the political argument change decisively. Three indicators: An important speech by Rep. Paul Ryan, the increasingly sharp tone of President Obama's rhetoric and the success of Occupy Wall Street in resisting attempts to marginalize the movement.

The most telling was Ryan's recent address at the Heritage Foundation. House Republicans regard Ryan as their prophet, their intellectual and their resident wonk. Usually, he carefully lays out the numbers and issues visionary promises of how cutting government (and taxes on the wealthy) will lead us down a blissful path to prosperity. He's sunny when everyone else is grumpy. So it was jarring to see Ryan used as the principal counterattacker against the president's efforts to make the injuries of class inequality clear.

Ryan spoke of his "disappointment" that "the politics of division are making a big comeback." He accused Obama of using "divisive rhetoric" and of "going from town to town, impugning the motives of Republicans, setting up straw men and scapegoats, and engaging in intellectually lazy arguments."

"Instead of working with us on common-sense reforms," he declared, "the president is barnstorming swing states, pushing a divisive message that pits one group of Americans against another on the basis of class."

Ryan would not have given this speech if the Republicans were not so worried that they are losing control of the political narrative. In particular, growing inequalities of wealth and income -- which should have been a central issue in American politics for at least a decade -- are now finally at the heart of our discourse. We are, at last, discussing the social and economic costs of concentrating ever more resources in the hands of the top sliver of our society. Ryan offered the classic defense of inequality, arguing that what really mattered was upward mobility, and that the United States had more of it than those horrible welfare states in Europe.

The only problem is that upward mobility has declined as inequality has grown, and social mobility is now higher in Europe than it is in the United States. That's shameful. And don't believe me on this: Republican presidential candidate Rick Santorum brought this up at a recent debate, backed by a study from the Economic Mobility Project. It's hard to justify more tax cuts for the wealthy in a country that is becoming more rigidly stratified by class.

All of which explains why efforts to taint Occupy Wall Street as nothing more than a bunch of latter-day hippie radicals haven't worked. It's why Obama, by sharpening his arguments about what's fair and what's unfair, has finally stopped his slide in the polls.

A recent survey by the Washington Post and the Pew Research Center showed Occupy to be more popular now than the tea party, which keeps losing ground. And as my colleague Greg Sargent has documented tirelessly, on many of the core issues (favoring higher taxes on millionaires and believing in a more even distribution of income and wealth) public opinion strongly supports the anti-Wall Streeters.

Obama's aides have a habit of congratulating themselves too much when things start going well. The president has a long way to go, and he is pursuing a strategy now that he resisted for a long time. But it ought to encourage the president that Ryan is terribly upset. Telling the truth about inequality is politically wise, and morally necessary.