Yin Wujou stared at the small characters "abandoned canal" on the map, a strange feeling suddenly welling up inside him. This discovery was too coincidental, so coincidental that it seemed as if someone had deliberately left clues here for them to discover. But then he thought, when A Yao's father made the atlas back then, he must have pieced together the truth bit by bit from old documents and on-site investigations in the same way. The Spirit Vein Bureau's skills were half on paper.
"Let's go to the abandoned canal first tomorrow," he said. "There are three springs; let's start with the closest one."
The next morning, the two left their horses at the inn, taking only dry rations, water bags, and a map, and walked eastward out of town. On the Hetao Plain in early autumn, most of the crops had already been harvested, leaving only stubble of wheat in the fields, gleaming pale gold in the morning light. After walking for about an hour, the terrain began to undulate, with farmland turning into wasteland, and wasteland then into gentle slopes overgrown with weeds.
A Yao compared the ley lines on the map with the actual terrain, stopping occasionally to make marks. Yin Wujou followed behind, observing the surrounding terrain. The soil layer in this area was indeed very thick, and the soil underfoot was dark brown and felt very solid. But the further east they went, the more gravel was mixed in with the soil layer. By the time they reached the top of the slope, the ground under their feet had turned into gravel and sand.
"It should be just ahead," A Yao said, pointing to a depression at the bottom of the slope. "The abandoned ditch is located on the north side of the depression."
The two walked down the slope into the depression. The depression was not large, and the surrounding slopes enclosed the land in a shallow bowl shape. Sure enough, there was a shallow ditch on the north side. The ditch walls were mostly covered by weeds and shrubs, but the outline of the bottom of the ditch was still visible. A Yao squatted down, pushed aside the grass on the ditch wall, and revealed the soil underneath.
"Brother Yin, come and see."
Yin Wujou walked over. A Yao pointed to a section on the canal wall where the soil was a distinctly different color from the surrounding area—a layer of dark gray silt on top, a layer of yellowish-brown sand below, and a thin layer of bluish-gray clay in between. A Yao picked up a small piece of clay, smelled it, and then rubbed it between her fingers.
"This is brought out by the spring water," she said. "The bluish-gray clay is only found near springs, which means this canal does indeed originate from a spring."
Yin Wujou squatted down to examine the layer of clay, then stood up and looked around. The terrain on the south side of the depression was even lower, so if the spring was here, the water should flow south. But the canal was heading north—up the slope. This meant that the people who built the canal were not diverting the water to lower ground for irrigation, but rather to higher ground.
"Water flows uphill?" A Yao had clearly noticed this as well, and she frowned. "Why would the people who built the canal do that?"
Yin Wujou did not answer immediately. He walked uphill along the canal for a while and found that the canal walls became narrower and narrower as he went up, eventually disappearing completely into the pile of rubble at the top of the slope. Standing at the top of the slope, he looked down and could see the entire depression. Suddenly, he noticed that there was a patch of grass at the bottom of the depression that was growing particularly lush and was much darker in color than the surrounding grass, maintaining its bright green even in the withered yellow of early autumn.
He walked down the slope and came to the patch of green grass. The grass was growing in the very center of the depression, forming an irregular circle about two zhang in diameter. He squatted down and pressed the ground with his hand, feeling a very thin, hard shell under the soil, which had a slight elasticity when pressed.
" A Yao," he called out.
A Yao ran over and was stunned when she saw the patch of green grass. She squatted down, touched the ground, and then flipped through the picture book to check the location. An expression of disbelief appeared on her face.
"There's something down there," she said, her voice a little strained. "The third spring marked on my father's map book is located right down here."
Yin Wujou stood up, pulled a short knife from his boot, and used the tip to dig a few times in the ground at the edge of the green grass. The soil layer was very thin; he dug less than a foot deep before hitting a hard object. He carefully brushed away the loose soil, revealing a bluish-gray stone slab. The surface of the slab was very smooth, and the edges showed signs of artificial polishing—this was not a natural stone slab; someone had deliberately laid it here.
A Yao also squatted down to help. The two cleared away the soil around the stone slab and found that the slab was about three feet square and its thickness was unknown. In the center of the slab was a fist-sized round hole with smooth walls, as if it had been washed by water.
"It's blocked." Yin Wujou looked at the round hole. "Someone sealed the spring with this stone slab."
"Why?" A Yao's voice was filled with confusion and anger. "Why block the spring?"
Yin Wujou did not answer. He inserted the dagger into the edge of the stone slab and tried to pry it open. The slab moved slightly, but it was very heavy and could not be pried open by one person. He straightened up and looked at the sky—the sun had risen high overhead, and the sunlight shone directly on the hollow, making the green grass look exceptionally bright.
"That's all for today," he said. "Remember the location, and bring your tools tomorrow."
A Yao nodded and drew a detailed sketch in her notebook, marking the location, size, and direction of the round hole on the stone slab. The two packed up their things and headed back. A Yao didn't say a word the whole way, only glancing back at the depression from time to time.
It was already evening when they returned to the inn. A Yao spread the sketch on the table and examined it over and over again by the light of the oil lamp. Yin Wujou sat beside her, reviewing the events of the day in his mind.
" A Yao," he began, "What were the labels for the first two springs like on your father's map book?"
A Yao turned to the corresponding page. "The first annotation is 'suspected spring revival,' dated last spring. The second annotation is also 'suspected spring revival,' dated the autumn of the year before last. Neither mentions the stone slab."
"That means the first two places recovered naturally, without any human intervention," Yin Wujou said. "Only the third place was sealed off. And it was sealed off hastily—the edges of the stone slab were roughly polished, and the position of the round hole was not correct. It seems like a decision made on the spot."
A Yao looked at him, something shifting in her eyes. "You mean, someone discovered the spring and then quickly blocked it?"
"Yes." Yin Wujou nodded, "Moreover, the people who blocked the spring know about the Spirit Vein Bureau. They know what the spring's revival means."
A Yao was silent for a while, then suddenly said, "Brother Yin, do you think... the disbandment of the Spirit Vein Bureau wasn't just because of the imperial court?"
Yin Wujou did not answer. He recalled what the Snow Empress had said— the Spirit Vein Bureau used to do this, to observe the direction of the earth's veins, detect anomalies in the earth's energy, record the changes in the spiritual veins of the world, and pass them on to future generations. This matter cannot be interrupted; if it is interrupted for ten years, many places will lose their connection. If someone is deliberately blocking the earth's veins, then the decline of the Spirit Vein Bureau will not be merely the result of court struggles.
"Rest first," he said. "Tomorrow we'll pry open the stone slab and take a look."