Liu Li spent several days flipping through the "Metal Technology" book that Fu Jingchen had given her. The book said that copper is soft and the shape of the file teeth affects cutting. She studied the diagrams for a long time, but when she picked up a file, something still didn't feel right. Theory is theory, but her hands just couldn't keep up. It was like groping in the dark with her eyes closed. She knew where to go, but she just couldn't place her feet correctly.

That afternoon, after finishing a rushed job, Liu Li stared at the several crookedly filed key blanks on the table, feeling a tightness in her chest. Just as she was lost in thought, Master Wang came over carrying an enamel mug and banged the lid on the workbench, interrupting her reverie.

"Pack your things and come with me." Master Wang's tone was curt, leaving her no room to ask questions.

Liu Li was stunned: "Master, where are we going? I want to practice some more..."

"Practice? With your current restless and impatient attitude, you'll be wasting your time practicing until next year!" Master Wang snorted. "Wash your hands and hurry up!"

Liu Li had no choice but to wipe the oil off her hands with cotton gauze and follow Master Wang out of the machining workshop. Instead of going to the technical department or the factory headquarters, she turned into the adjacent machine repair workshop—it was even more stuffy there than the machining workshop, with the smell of machine oil mixed with the metallic odor of hot iron. Several disassembled machine parts were piled on a large table, and several experienced workers were busy working around them.

Master Wang didn't go over there, but led Liu Li to a corner. There was an old fitter there, his hair mostly white, his hands calloused thicker than copper coins, squatting there scraping a large cast iron plate.

The rough iron plate in front of the old fitter was very rough, covered with knife marks. He didn't rush to cut it; first, he rubbed the surface of the plate with his palm, as if handling some treasure. Then, he scooped some red ink from an old tin can, spread it evenly on a smooth, standard flat plate next to it, placed the flat plate on the cast iron plate, pressed it gently, pushed it back and forth a couple of times, and lifted it up to see—the iron plate was marked with many small red dots, which were the marks of high-point contact.

Only then did he pick up the scraper. The old fitter's movements were slow, yet frighteningly steady. The scraper seemed to have eyes in his hands, landing precisely on the small red dot. With a gentle twist of his wrist, the iron filings floated down like thin sheets of paper. After scraping a few times, he would apply ink, grind it, and check the red dot, over and over again, without haste or impatience.

“Look at his hands,” Master Wang whispered in Liu Li’s ear, his voice softer than usual. “Don’t be fooled by his slowness; he knows what he’s doing. He’s not scraping iron; he’s scraping the 'flatness' in his mind. He knows where his hands are high and low, how much force to apply, and how to deflect it—it’s all in his mind.”

Liu Li held her breath and stared intently. The old fitter sometimes even closed his eyes, relying entirely on the feel of his fingers to guide the scraper. His breathing was as even as a pendulum, and the "swish" sound of the scraper scraping against the iron plate was as light as the wind blowing through the leaves. The originally rough iron plate slowly became smooth, and the small red dots became denser and more even.

"Only when the water is still can you see things clearly, and only when your mind is calm can you use your tools effectively," Master Wang said. "What you were doing before was just busywork, but this is what you call 'doing work'—putting your heart into it."

Liu Li's heart skipped a beat. She suddenly realized that all she had been thinking about was "getting the key filed quickly," and she was struggling with the tools and copper. How could she possibly do a good job? The experienced fitter was breathing smoothly with the scraper, but she hadn't even broken in her hands and the file.

Master Wang didn't linger. He took her to the window of the heat treatment workshop to watch the master judge the temperature by the color of the furnace fire—that was based on decades of experience, not something you could learn by looking at a watch.

Back in the workshop, Master Wang didn't ask her to get a file right away. Instead, he picked up the old file she used and ran his fingers along the teeth: "This file has been with you for so long. Have you figured out its temperament? The coarse teeth are suitable for filing quickly, and the fine teeth are suitable for smoothing. If you use too much force, the teeth will break easily, and if you use too little force, it will be inefficient."

He picked up another piece of brass blank and weighed it in his hand: "This brass is soft, so you can't cut too hard, or it will chip easily; but you can't cut too lightly either, or you'll file for a long time without any change. These things are in the books, but the books don't tell you how to adjust the force in your hand - you have to figure it out yourself."

“Don’t just think about ‘making a key’.” Master Wang looked at her one last time, his eyes deep. “First, think about ‘how to use the file smoothly’ and ‘how to file the copper comfortably’. Focus your mind on the things in your hands, forget about the competition, forget about winning or losing, and even forget about yourself. When you feel that you are not ‘using’ them, but working with them to ‘get the job done’, you will get through this hurdle.”

After saying that, Master Wang turned around to pack up his tools, picked up an oilstone and slowly sharpened his chisel, as if he hadn't said anything at all.

Liu Li stood there, pondering her master's words for a long time, and then she remembered the old fitter's scraping and grinding. Suddenly, she understood. She sat down again, not in a hurry to take the key blank, but first picked up the old file, closed her eyes and felt its teeth, and could even feel the patina on the handle; then she picked up a new copper blank, held it in her hand and felt its weight and edges.

When she started filing again, she stopped focusing on the result of "it must go in" and instead started to think about the feel of the file – if she pushed too hard, the copper filings would be coarse, and if she pushed too lightly, it would be too slow; if the angle was a little off, the bevel would not be round; when she switched to a fine-toothed file to polish, she had to walk slowly close to the surface, otherwise it would be easy to create sharp edges.

As darkness fell, she was left alone in the workshop, but she felt neither tired nor annoyed. The file moved, the "reaction" of the copper material entirely in her hands. She adjusted it accordingly, trying again if necessary, her mind as calm as still water.

Finally, she picked up the key that had been repaired again and again, and inserted it into the "lock cylinder"—

"Click".

With a soft, almost inaudible click, the key slid smoothly to the bottom without any jamming, fitting perfectly.

Liu Li wasn't overjoyed, but she felt incredibly at ease, as if a long-standing stone had finally been removed. She finally understood what her master meant by "a hand with a sense of touch, a mind as still as water"—it wasn't about mastering any particular technique, but about truly becoming "familiar" with the tools and materials in her hands, calming her mind, and naturally making the work go smoothly.