President Trump has always understood the power of symbolism. As a real estate developer, he counted on it to turn his ambitions into reality: Create physical manifestations of what you want people to believe, and eventually they'll believe it. Put your name in 20-foot-high letters on the side of a building, and people will think you're a giant.

Despite his many business failures, Trump never lost faith in that kind of symbolism. When he ran for president, one symbol rose above them all: a big, beautiful wall on our southern border. And who's going to pay for it? Mexico! It isn't too much of an exaggeration to say that wall put Trump in the White House.

But as you may have noticed, 14 months into Trump's presidency the wall remains unbuilt. He still dreams of it, though; just on Monday, he made it one of the centerpieces of his speech on the opioid crisis, saying he "will build the wall to keep the damn drugs out." And he's still trying to make a deal. As Burgess Everett of Politico recently reported, over the weekend the White House tried to reach an agreement with Democrats to allocate $25 billion to the wall, in exchange for extending protections for the DREAMers until the fall of 2020. The Democrats balked, demanding that those protections be made permanent, and no deal was made.

Trump is getting ready, though. He recently went to California to inspect border wall prototypes, although not all of them satisfied his oft-stated desire that the wall be see-through, so you can tell what those crafty Mexicans are up to on the other side. After reviewing the proposals, he noted that the wall needs to stop Mexicans who are like "professional mountain climbers," and for the Spanish speakers in the crowd, explained that "we want to make it perfecto."

While the wall won't ever extend over 2,000 miles of border, it's a good bet that eventually Trump will be able to build enough new border fencing here and there to proclaim that he built his wall (in case you weren't aware, he's not above the occasional exaggeration when it comes to his accomplishments). Trump immediately saw the kind of reaction he got on the campaign trail when he mentioned a wall, and with his keenly honed sense for white people's grievances, he knew he had a winner. The wall would be not just an impediment to illegal immigration, but a way of stopping change itself. It would keep out the foreigners who prevent our communities from being frozen in time, bringing their unfamiliar language and food and music to the point where nothing is like it was when you were a kid.

When Trump said he would make America great again, he was promising to turn back the clock, to transport you to whenever you thought times were simpler and better. But before you can turn back the clock you have to stop it, and that's what the wall would do.

And Mexico paying for it? That was far more than a throwaway line. It was at the core of Trump's appeal to "the forgotten men and women," particularly the men. It was about us asserting our dominance, forcing the Mexicans to bow down before us in abject humiliation, not only submitting to a project they despise but forking over the money to pay for it.

It was central to the larger argument that Trump made to his most ardent supporters. You don't have the job security you once did, life has become uncertain and unsettling, the world is changing in ways you don't understand and don't like, and you walk through your days feeling diminished and ignored. But elect me and you can stand tall again. We'll show everyone who's boss — we'll even make the Mexicans pay for the wall that shuts them out. That Mexican payment will be like Popeye's spinach coursing through our muscles, restoring us to our former powerful self. Everyone will see, and everyone will know.

Of course, Trump always knew it would never happen. Just a week after taking office, he had a phone call with Enrique Peña Nieto in which he begged the Mexican president to stop saying publicly that he'd never pay for the wall. "If you are going to say that Mexico is not going to pay for the wall, then I do not want to meet with you guys anymore because I cannot live with that," he said, imploring Peña Nieto to evade the question by saying "we will work it out."

But Peña Nieto was not fooled. "This is an issue related to the dignity of Mexico and goes to the national pride of my country," he said, which was exactly the point — a public blow to Mexico's dignity and pride was just what Trump wanted, because as far as he's concerned, if you're not dominant, you're submissive. America pre-Trump was submissive (note how often he says other countries are "laughing at us"), but now with him in charge we're the ones who push other countries around.

Yet when he's asked about the wall these days, Trump tends to be vague and evasive, or try to insist that even if the Mexicans are not paying, they're really kind of paying, or at least they will. "The Wall will be paid for, directly or indirectly, or through longer term reimbursement, by Mexico, which has a ridiculous $71 billion dollar trade surplus with the U.S. The $20 billion dollar Wall is 'peanuts' compared to what Mexico makes from the U.S. NAFTA is a bad joke!" he tweeted in January, which isn't exactly the emphatic language of the alpha male exulting in the submission of his vanquished foe.

But now Trump wants American taxpayers to shell out $25 billion for a wall, or part of a wall. Even if we do, and even if some more wall-like fencing gets built, the underlying justification will not be satisfied. America will keep changing, and being changed by immigrants, just as it always has. The old will feel angry and alienated by those changes, just as they always have. Things will not one day be as simple as they were when you were a child, because you're no longer a child.

And no wall will give anyone back what they've lost.