If you want a good illustration of America's gaping class divides, look no further than the University of Michigan. In that school's newspaper, Michigan Daily, student Jesse Klein last week wrote a controversial op-ed about what she characterized as her family's modest means. Here's how it began:

My family's household income is $250,000 a year, but I promise you I am middle class. I live in a $2 million dollar house, but I promise you I am still middle class. It has one story, doesn't have a pool or its own movie theater. It is a modest three-bedroom, two-bath.

Klein explained that her view on money changed when she got to college, as she found that Michigan residents spend differently from people in California, her native state — partly due to the cost of living, but partly because she thinks the people in Ann Arbor use money more as a status symbol.

The piece (judging from the comments section) elicited no shortage of outrage. But it also provoked a thoughtful response from another student, Jenny Wang. Her piece wasn't so much a takedown of Klein's op-ed but instead focused more what her experience with money has been, writing that Wang's mother earned $30,000 until being laid off, and now makes "an inconsistent $900 a month." In it, one sentence gets at perhaps the most important point about what it means to be rich or poor in America (emphasis mine):

And that, I think, is my main point: how money gives people options. It sounds like such a cliché, but the thing to remember is that clichés originate from an experience that is true, regardless of how many times they are uttered ... I think it's important to keep in mind that there's a difference between having a family who needs to save some money here and there to afford an out-of-state school, and having a family who knows that the out-of-state institutions are not even up for consideration.

Wang is getting at something very important here — often we write (and think) about wealth or incomes in the abstract, just as how many zeroes are on a person's paycheck and what quintile of the income distribution that puts them in (are you a 1 percenter? 10 percenter?). Or we focus on what people are able to buy, like opulent homes or cars. But Wang is talking about perhaps the most important (and invisible) accessory that comes with wealth: opportunity. Poorer Americans disproportionately spend their money on necessities like groceries, as I found earlier this month, while the rich have more options of what to do with their money, and end up spending on luxuries and retirement accounts. Likewise, while richer kids may have had their pick of schools nationwide, Wang writes that financial aid and scholarships are what gave her the option to study computer science at the University of Michigan, located in her home town of Ann Arbor.

Wang's story squares well with something writer Linda Tirado told me last year about her former life below the poverty line:

It's the question of startup capital, really: if you can spend your money up front in the right places wisely, then you'll save money in the long term. But if you're constantly struggling just to kind of patch it up and make ends meet, you're taking whatever the most convenient option is, which is inherently going to be more expensive.

Tirado was talking about investing in everyday objects like cars and groceries, but she may as well have been talking about education. It's less expensive right now for someone like Wang to work instead of going to college, but given the option, college is a far better long-term investment and puts a lower-income student in a far higher income bracket, as my colleague Libby Nelson recently wrote.

Having money gives you the option to invest, which creates more options. That's true not only in education, but in other important investments, like retirement.

Meanwhile, higher-income families may continue to consider themselves middle class, which isn't all that unusual. Curiously, up and down the income spectrum, many Americans are predisposed to think of themselves as middle class, the Wall Street Journal has found. And both Obama and Romney at some point during the 2012 election cycle classified American families earning around $250,000 or under as middle class. It's also true that a family earning $250,000 can feel strapped for cash, and Klein is definitely right that cost of living makes a huge difference there, particularly in a super-high-cost place like Palo Alto, where she's from.

But there are people who make only a fraction of that who are also in that "middle-class" swath of Americans. There's a huge gap between those two groups of people, and at its most basic level, it's not about numbers or percentiles or even the stuff they can buy; it's about the freedom that comes with a higher income.

[h/t The Billfold]