I saw "Lincoln" over the weekend and thought it was both great fun to watch and weirdly amateurish, as if Hollywood's A-list had all decided to pitch in on a community theater production about Abraham Lincoln. 

Bill O'Leary/The Washington Post

At the same time, I've been reading Stephen B. Oates's Lincoln biography, "With Malice Toward None." Early on, Oates recounts Lincoln's courtship of Mary Ann Todd (later to become Mary Ann Lincoln). At the time, Lincoln is, by any stretch of the modern imagination, a catch: Born to nothing and still a young man, he's built himself a thriving legal practice, gotten himself elected and reelected to the Illinois legislature, and already achieved some national renown as a Whig orator. This isn't just a young man on the make. It's a young man who seems to have made it.

In 1840, Abraham Lincoln and Mary Ann Todd "reached an 'understanding' and evidently became engaged." Then, Todd's family stepped in and killed the budding romance. Lincoln, they felt, came from "nowhere," while the Todd family was wealthy and educated. Lincoln was informed he was no longer welcome to visit Mary Ann Todd, and the engagement, at least for a time, was off, throwing Lincoln into a particularly black depression.

"Lincoln was devastated," writes Oates. "The hostility of the Todd and Edwards families -- especially [Mary Ann's older sister] Elizabeth -- caused incalculable pain in one so insecure about himself and so resentful of his own family that he hadn't visited in over nine years. One of Lincoln's greatest sorrows -- from his view -- was that he'd worked himself to the bone for recognition and success and yet carried a social albatross about his neck: the lack of family respectability."

Abraham Lincoln and Mary Ann Todd would eventually marry. But what's remarkable about this vignette is the tensions you see in the American class system. On the one hand, there was -- and, to a lesser degree, is -- an American class system. The idea that America is a classless society is now, and has always been, a myth. On the other hand, a guy who wasn't initially thought good enough to marry into the upper crust was nevertheless able to become president. That part of the American story is real, too.

One accelerant to American social mobility has always been that our class system was weaker than the European class system, in part because our country was younger than the aged civilizations of Europe. It might be difficult for an Abe Lincoln to marry a Mary Ann Todd, but it was nevertheless possible for an Abe Lincoln to become a successful politician by the age of 25, and a successful president thereafter.

But the European class systems have weakened, too. And with that accelerant gone, our historical edge in social mobility is eroding, too. The Pew Charitable Trusts' project on economic mobility looked at 16 studies on the subject and concluded that in "the United States, there is a stronger link between parental education and children’s economic, educational, and socio-emotional outcomes than in any other country investigated."

Part of the genius of the American system has been the recognition that the country benefits from a less ossified class of elites. Where the class systems of other cultures held that there was a certain segment of the population that was born to rule and everyone would suffer if the common man rudely shouldered his way to the front, Americans believed we were better off if men like Lincoln -- men born to illiterate parents in log cabins -- had the ability to lead the nation. And we were right. Those who are born to rule often beget children who are born to spend down their parents' fortune and besmirch the family name.

The sweep of American inequality is not as broad as it once was. But there is still a vast distance from the top to the bottom, and it's becoming harder to traverse here than it is to traverse elsewhere. In part, this is due to what Christopher Hayes, in his book "Twilight of the Elites," calls "the iron law of meritocracy," which holds that "eventually the inequality produced by a meritocratic system will grow large enough to subvert the mechanisms of mobility . . . those who are able to climb up the ladder will find ways to pull it up after them, or to selectively lower it down to allow their friends, allies, and kin to scramble up."

America is a country that not only permits its log cabin presidents, but celebrates their humble origins. It's also a country that just chose to reelect an African American president who was born to an absentee Kenyan father rather than the son of a former governor. Even Lincoln would raise his eyebrows at that.

But it is also, at this moment, a country in which many are eagerly looking toward a 2016 presidential race in which the Republican frontrunner is a Bush and the Democratic frontrunner is a Clinton. And, further down the ladder, it is a country that is falling behind its peer group in social mobility. Class is less binding today than it was in Lincoln's time, but circumstance is more binding than it was fourscore and seven years ago.