“Something there is that doesn’t love a wall, that wants it down,” wrote Robert Frost many years ago in “Mending Wall,” one of his greatest poems. It’s also one of his least understood.

How often have my hackles raised as some letter-to-the-editor writer or Internet poster has tried to justify political isolation, missile defense systems, or social exclusion by ascribing to the poet the aphorism, “Good fences make good neighbors.”  What Frost’s poem actually says is that those who love walls are relying upon principles from the Stone Age.

Human societies have been building walls from time immemorial. They exist on every continent except Antarctica. They were all, as far as we know – except, perhaps, the Berlin Wall – built for defensive purposes. And against all reason, we appear to be about to do it again.

The Great Wall of China is the most famous, for good reasons.  Actually several walls built over about two thousand years, and approximately 4000 miles long, it was meant to exclude and control the nomadic, marauding “others” from the north – what’s now Southern Mongolia.  Its construction required the expenditure of immense resources and cost an estimated two to three million workers’ lives.  It was much embattled and occasionally breached.  In the end it failed from within, when a disgruntled general in charge of defending a corrupt government opened the gates to the Manchus, who defeated the existing Shun dynasty, instituted their own, and started building yet another wall, in the south this time, to protect against aliens from southeast Asia.

Roman soldiers and engineers built walls on almost every frontier of the Empire, again at vast expense.  The best-known of them is Hadrian’s Wall, begun just after a visit to Britain by the emperor Hadrian in 122 AD.  The empire had by that time passed its zenith, and was being pressed on all sides, from Egypt to Libya to Germania.  Its reaction could have been inclusive, but its instinct was to wall out what we would call undocumented aliens and keep them out with a heavy military presence along Rome’s borders.  Quite naturally, the empire collapsed from within.  When during the winter months around 400 AD the rivers north of Rome froze over, there was no one left at home to defend it against the hungry, aggressive Germanic tribes who crossed on the ice and sacked the Eternal City. Hadrian’s Wall is today a popular tourist attraction and hiking trail, much cherished by the people it was originally intended to exclude and control.

There are massive walls in the Andes, most notably at Machu Picchu and Sacsahuamán, near present-day Cuzco. Their huge stones, up to 450 tons apiece, were fitted together with incredible precision by sophisticated engineers and stonecutters. The purpose, again, was defensive; they probably were built during the early days of the Spanish Conquest. And again, in the end, they were ineffective: The Inca are no more.

Even West Virginia has ancient walls, on ridges above the Kanawha River. They’re several miles long, apparently built as a refuge when the settlements in the valley were attacked, and were occupied probably three times between 500 and 1500 AD. Whether they performed their purpose we will never know. The builders and defenders were gone before the European immigration.

Consider all the impregnable walled cities that are no more as they were – Babylon, Nineveh, Carcassonne; the list is virtually endless.  You’d think that over the centuries somebody would have tumbled to the fact that, in the end, walls don’t work; that, actually, they seem to attract unwelcome attention – because they’re attempting to protect what many people outside them want.  One of my favorite stories is of Urquhart Castle on Loch Ness, Scotland, now a romantic ruin. It was attacked and taken and fought over so many times that its last occupiers apparently looked at each other one day in 1692 and agreed that defending it was becoming a never-ending drag.  So they blew its defenses to bits and marched away.  Nobody has fought over it since.

We’re still building walls today, of course, in defiance of millennia of history. The Berlin Wall that scarred Germany from 1961 till 1989 was built not to keep aliens out, but to prevent East Germans from escaping. It disintegrated, not because Ronald Reagan famously inveighed against it in a speech, but when the political and military will to maintain it dissolved from within. We Westerners considered it an excrescence constructed by an “evil empire.”

So what do we make of the newest ones, between Israel and Palestine and the United States and Mexico? We’re told they’re responses to “security issues” – though how the family who picked the tomato we had for lunch is a security threat is not clear. It just seems to me that after all the attempts we human societies have made to wall out our problems, and considering the results, we might for a change try something someday besides the traditional political/military response. Leaders who advance their own ideologies and protect their fortunes by playing on citizens’ fears are serving them dishonorably. They’re like Robert Frost’s wall-mending farmer neighbor: I see him there bringing a stone grasped firmly by the top in each hand, like an old-stone savage armed.  He moves in darkness as it seems to me, not of woods only and the shade of trees.  He will not go beyond his father’s saying...He says again, “Good fences make good neighbors.”