Read the passage
[1] On my third afternoon in the pottery studio, I was still measuring my progress by the number of bowls I could finish. The instructor, Lena, measured something else. She would lift a bowl, turn it in her hands, and ask where I thought the clay was thickest. I usually pointed at the rim, where I could see the unevenness. She usually pointed at the base, which I had hurried to hide beneath a neat circle.
[2] By Friday I had made a bowl whose rim looked level from every direction. I set it on the shelf by the window, away from the practice pieces that leaned and sagged. When Lena asked whether I wanted to cut it in half, I thought she was joking. The bowl was still soft enough to slice, she explained, and a cross section would show how the wall changed from bottom to top. I told her I would rather keep it. She nodded and went back to the wheel beside mine.
[3] The following afternoon, my bowl had developed a crack near its base. I turned the damaged side toward the wall before Lena arrived. She noticed the movement but said nothing about it. Instead, she took a wire through a bowl she had just made. The two halves fell apart with almost no sound. Inside, the clay walls were thinner than I had expected and nearly even all the way down. She put one half on my table and asked me to compare it with my bowl by touch.
[4] I pressed a thumb inside my bowl and held my fingers beneath it. There was more clay between them than I had imagined. I had mistaken the narrow foot on the outside for a thin base on the inside. The shape I could see had concealed the part I needed to understand. Lena did not announce that the mystery was solved. She asked what I would change in the next bowl, and I described a slower movement of my fingers near the center.
[5] A week later, I made two bowls from equal lumps of clay. One looked better than the other. Before either could dry, I sliced the better-looking one in half. Its wall narrowed abruptly just above the base. The other bowl, still turning on the wheel, suddenly seemed less like a disappointing copy and more like an opportunity to try a correction while the clay was workable. I moved my fingers lower and watched the curve change.
[6] At the end of the month, I took three finished bowls home. I also took the half bowl Lena had given me, wrapped carefully in newspaper. It was too rough at the cut edge to use for anything. On my desk, however, it reminded me of a distinction I had not understood when I first admired that level rim: finishing an object and finding out how it was made were not always the same achievement.