For three years, we've read much about walls in your newspaper.

Our president is determined to have a really big one along the southern border, and The Republic won a deserved Pulitzer examining the topography of the border and the challenges facing the building of such a wall.

Physically, however, isn't the idea a non-starter because we all know it won't actually work?

As Janet Napolitano joked, for every 6-foot wall there's an 8-foot ladder.

Have any walls ever been successful? I lived for 20 years on one side of Hadrian's Wall. It was built in A.D. 130 and marks the boundary of the Roman Empire. Rather than prevent people crossing, it functioned as an early warning system so if the savage Scots decided to attack, the Roman legions stationed in York had time to march out to meet them.

But as the empire crumbled, the Vikings moved in. The need for a wall disappeared and its stone was used to build cottages.

The Great Wall of China was another feat of engineering and was, over the centuries, part defense system, part territorial definition and philosophically the spirit of China itself.

If this is what we want, then we better get started - the Great Southern Wall of America would take a few hundred years. If it is to express the spirit of the United States, we'll need a wall that doesn't look like my next-door neighbor's picket fence.

Since the president is not getting worked up about building a Great Northern Wall, I can only assume that Canadians are not looked on as threatening, probably because most are white, reasonably wealthy, whipped two armies America sent to take them over, and they have little desire to escape from their own country, except when the weather gets too cold.

To the south, however, there are numerous countries that are poor and are not inhabited by Caucasians. The desire of these people to come to a safe country is a powerful incentive. The U.S., having accepted the poor of Ireland and Italy and the persecuted of Eastern Europe, now seems unwilling to open its doors to the poor south of its border.

The obvious solution is to help these poorer countries develop their own infrastructures and natural resources.

To help develop these countries is in our own interests; eventually, we may all own holiday apartments in Nicaragua or Guatemala or Panama.

The property market in Mexico is doing well. Half of Texans seems to live there. Surely it would be more sensible to invest the billions we were going to spend on a wall building up poorer countries south of the border.

If all this talk of walls is not about physical walls, could it be a mental attitude, the same attitude that branded the Irish and the Jews as subhuman when they came off the boats?

What are we saying? "We don't like people who are different. This is OUR piece of the Earth, and even if we stole is from the native populations and devastated them with diseases, we are not going to share it!"

The irony is that most of us are descended from immigrants, that our ancestors came over the fence at one time or another, that Arizona was once part of Mexico and that we need immigrants to sustain and grow our economy.

If there is to be a solution, then we all need to get over our fear of foreigners and give our support to an orderly process that controls legal immigration, offers citizenship to those who have worked and paid taxes here, brings illegal immigrants out of the shadows and, above all, educates and develops the potential of all.

At the same time, by helping our southern neighbors, we can build a prosperous future for everyone.