In my last year of high school, we briefly studied the Great Wall of China. We learned that the first emperor of the Qin (Ch’in) dynasty had walls built as a defense against raids by nomadic peoples. Construction began centuries before the sections most people recognize today, and later dynasties repaired, rebuilt, and extended the fortifications. Much of the Great Wall that survives today dates from the Ming dynasty (1368–1644).

During one class, our teacher mentioned that despite the wall’s remarkable strength, parts of it were crumbling. He asked us what materials the Chinese might have used to hold the masonry together, pointing out that modern cement was not available to them.

I raised my hand and said, “Maybe they used dirt and rice.”

The teacher looked shocked.

“What a stupid answer,” he said.

He dismissed my suggestion and explained to the class that China had many hungry people who needed rice for food. I was humiliated. I hated being belittled in front of the class, and after being labeled stupid, I stopped raising my hand.

Years later, I learned something that brought that moment back to me. Researchers studying ancient Chinese construction discovered that builders had, in fact, used sticky rice in some mortars. The rice was combined with lime to create a remarkably durable mortar, helping explain the strength and longevity of certain structures.

I would have loved to go back to that teacher and tell him that my supposedly “stupid” answer had not been so stupid after all. Unfortunately, he died years ago.

But what stayed with me was not simply that he had been wrong. Everyone is wrong sometimes. What troubled me was his unwillingness to consider an unexpected possibility—and the damage that can be done when someone in a position of authority dismisses an idea before examining it.

That experience taught me something about the danger of closed minds.

Years later, I encountered something similar in the mental-health profession. I consulted a psychiatrist who seemed unable to look beyond the theories she had learned. Instead of trying to understand my experience on its own terms, she appeared to be searching for a theory into which I could be fitted.

At one point, she asked me, “Which theory fits you?”

That question has stayed with me.

I spent considerable time and money on those sessions, yet I felt I made little progress. Instead, my feelings of guilt increased, and I became increasingly hopeless. I began to believe that depression was simply something I would have to live with.

The two experiences were very different, but for me they shared an important lesson. Knowledge matters, and expertise matters, but neither should close the door to curiosity. A theory can help us understand reality, but it can also become a barrier when we insist that reality must conform to the theory.

Sometimes the possibility that sounds foolish at first deserves a second look.

Sometimes there really is rice in the wall.