I was once a stone mason. I know something about walls.

Some walls I built still stand in Texas, walls to keep floodwaters under control, fireplaces for heating houses, columns to support roofs, foundations for a public school. They exist because they have a useful purpose. Some rock structures were built to satisfy a property owner’s concept of beauty. One of many cut-stone fenceposts in a decorative fence around a mansion now supports a mailbox. Other things I built were torn away decades ago.

As part of a scientist exchange program with China, I was one of the first Americans in decades to visit China’s Great Wall. I visited it with some of China’s best scientists. The Great Wall as we know it is made up of about 3,900 miles of wall, over 200 miles of trenches and about 1,400 miles of natural barriers such as hills and rivers. The “wall,” with its many starts and stops is estimated to be about 13,000 miles long.

Some walls may have been built as early as the 7th century BC. These joined together with later walls are now referred to as the Great Wall. Some of a wall built around 220–206 BC by the first emperor of China remains. Walls have been rebuilt, maintained and enhanced for centuries. Some of what we call the Great Wall is from the Ming Dynasty, about the time Columbus discovered America.

Forty years ago, I sat on the western end of that Great Wall. It was a mound of strange soil and broken household items. There the Great Wall was not made of stone, but adobe blocks. Chinese scientists told us that for five centuries people from Chinese towns and villages were forced to build structures that never really provided safety from enemies or admiration from friends.

I watched a camel caravan pass to the east of us and thought about what our scientist friends had told us. The main purpose of the Great Wall was not for safety from enemies, but for regulation of trade and control of immigration and emigration. It served as a transportation corridor with watch towers, troop barracks, garrison stations and communication centers. What we now call the Great Wall is probably remains of many walls used for various purposes. The Great Wall, or Walls, are mainly a tourist attractions today.

Chinese are not the only people who built walls in ancient times. Roman Emperor Hadrian, who ruled the northern British Isles from A.D. 117 to A.D. 138, built a wall about A.D. 128 that stretches between the North and Irish seas near the border of England and Scotland. No one really knows why ancient Chinese or Hadrian built walls between them and their neighbors.

Our current president says he wants to build a wall between us and Mexico to protect our borders. He justifies it by saying the action is like an individual building a human-proof fence around his house.

Decades ago I was nominated to be director of the International Livestock Center for Africa (ILCA). They flew Jenny and me to Addis Ababa, where the institute was located. The position came with a car, driver, servants, a fully furnished historical mansion, a beautifully landscaped estate of about 20 acres surrounded by concrete fence four meters tall. Rare birds and animals were fed imported food.

It was an island of beauty surrounded by hundreds of starving people in makeshift camps cleared out occasionally by the military. They offered me the job, but we declined. It would have been a cool place in hell where we lived in luxury and people starved only a thin wall away.

I was never more proud of my country than when Ronald Reagan, a Republican president I did not vote for, stood by the Berlin Wall and said, “Mr. Gorbachev, tear down this wall.”

And I have never been more ashamed of an elected official than the current occupant of the white house who wants to build a wall that violates the very attributes that make our country great.

Thad Box

Thad Box is professor emeritus in the Quinney College of Natural Resources at Utah State University, serving as dean of the college from 1970 to 1990.