Lu Ban? Of course, I know him, the patron saint of carpenters. It’s said he invented the ink marker and the Lu Ban ruler. Later generations have a saying: “Wielding a big axe before Lu Ban’s door,” which mocks those who overestimate themselves and show off their skills in front of experts.

Shen Gun said, “He was much more than just a carpenter. Have you heard the legend about him? They say he once built a wooden bird that could fly in the sky for three days and three nights without landing.”

Luo Ren laughed out loud. He had heard the story, but wasn’t it just a legend? How could something made of wood fly in the sky? And for three days and three nights—even airplanes couldn’t manage that.

Shen Gun became quite angry: “Little Radish, you people just have no culture, no imagination. How sad! So very sad!”

He demanded that Luo Ren admit his shallowness, or else he would stop talking.

Leaning against the car, Luo Ren couldn’t help but smile. People were coming and going on the busy street, shadows moving inside the mobile service center. On the other side, Cao Yanhua was haggling with a seller, tugging on a rooster’s tail—Shen Gun truly wasn’t a person living in the mundane world, actually demanding an apology for an unsubstantiated legend.

Luo Ren played along: “Most of the time, I am indeed quite shallow.”

Shen Gun seemed to feel better, snorting through his nose before finally continuing.

“So later, there was a saying that the wooden bird became Lu Ban’s symbol. Many of the ingenious contraptions he created afterward would bear the mark of the wooden bird.”

He told Luo Ren about his discovery in the beam at Yin Erma’s house.

The information seemed rather overwhelming: something built by Lu Ban over two thousand years ago, appearing in a groove on Yin Erma’s house beam, and made of wood—after all these years, it hadn’t decayed?

Luo Ren had many questions but held them back. Otherwise, Shen Gun would scold him again for being shallow and ignorant.

When conversing with Shen Gun, it was best to just listen quietly.

“Lu Ban was a real historical figure. Chronologically, he came after Laozi, around the same time as Mozi. Some people called him Gongshu Ban or Gongshu Zi. I think calling him a carpenter somewhat diminishes him… Have you heard the story of Mozi stopping Lu Ban from attacking a city?”

Luo Ren had heard it. There were even films and TV dramas based on it. Supposedly, Lu Ban made scaling ladders to help the Chu State attack Song, and Mozi came to stop him to prevent suffering. After a verbal battle of simulated attacks and defenses, Lu Ban was convinced and made peace with Mozi.

“After that, Lu Ban had a realization. He studied all kinds of mechanical devices and was fascinated by various mechanisms, which led him to enlightenment. In his view, everything in the world was part of some mechanism.”

At this point, Shen Gun paused. These past few days, in his own words, his mind had been full of this matter. He was “thinking,” and wasn’t sure if he could explain it clearly.

“Let me put it this way: a flash flood dislodges a rock, the rock falls and kills someone, after that person dies, no one feeds their chickens, so the chickens run out looking for food and end up being caught and roasted by passersby. In this chain of events, the initiating mechanism was the flood dislodging the rock… Do you understand, Little Radish? I’m already explaining this in very simple terms.”

Luo Ren was confused, but he could follow the logic: “Isn’t that just like the butterfly effect? A butterfly in the Amazon rainforest occasionally flaps its wings, and perhaps two weeks later it causes a tornado in Texas—according to your theory, the butterfly flapping its wings is also a type of mechanism.”

Shen Gun gasped: “That’s exactly it!”

The butterfly effect comparison—why hadn’t he thought of it himself? This Little Radish was somewhat cultured after all.

Shen Gun cleared his throat and continued: “Another example: tides. The changing distance between the moon and the Earth causes changes in the ocean water. This, too, is a mysterious mechanism that you cannot see.”

Luo Ren frowned: “Gravitational force between celestial bodies? Wasn’t that discovered by Western scientists? Did Lu Ban already observe this back then?”

The slight appreciation Shen Gun had developed for Luo Ren because of the “butterfly effect” comment instantly vanished: “That’s why I asked you at the beginning if you believe that the wisdom of the ancients surpassed that of modern people. Lu Ban might not have known what gravity was called, but he knew that within the mysterious workings of heaven, such mechanisms exist! Mechanisms!”

Fine, if he says mechanisms, then mechanisms it is. Luo Ren voluntarily admitted his error: “It’s my lack of imagination. I’m shallow.”

Shen Gun wasn’t a fool and heard the reluctance in his tone: “Have you heard this folk rhyme? ‘Cangjie created characters worth one dan of millet, passed to Confucius nine dou and six. Four sheng were kept secret, left for Daoist priests to draw talismans. Confucius learned characters worth nine dou and six, and passed to his disciples a full eight dou. Since then, being learned means five carts, since ancient times, talent means eight dou.”

Luo Ren had never heard this before: “What does it mean?”

“It means that your ‘great talent’ merely amounts to knowing eight dou of characters. Cangjie created characters worth one dan of millet, and even Confucius only knew nine dou and six—you haven’t even learned all the characters, yet you readily question whether our ancestors were as wise as you!”

That was quite an accusation, but Luo Ren could see that Shen Gun had been “thinking” about this issue for the past few days, inevitably becoming mentally and physically exhausted, overheated, and irritable.

Luo Ren was good with words: “I wouldn’t dare. The legacies of our ancestors—the Eight Trigrams, Purple Star Astrology, the Book of Changes—we later generations still haven’t fully understood them.”

Knowing one’s mistakes and being willing to correct them is a great virtue. Shen Gun found him agreeable again: “Then let’s continue talking about tides.”

Why discuss tides again? Was there a connection to what was happening now? Luo Ren was somewhat distracted, suddenly thinking: someday he should take Mu Dai to walk on the beach and see the ebb and flow of the tide…

Shen Gun said something that Luo Ren didn’t catch clearly: “What?”

“I said, the human body is also eighty percent liquid, so if the moon’s gravity can affect the ocean, it will also affect the human body. Scientific research has found that during full moons, people’s emotions are more easily stirred—crime rates increase, illness rates increase, incidents of blood vessel ruptures increase, and so on.”

Luo Ren blurted out: “You’re talking about science now?”

Shen Gun jumped up: “What’s wrong with talking about science? I’m going to be a department chair at a university someday—there’s a famous saying that the supernatural and the paranormal are sisters to science. Haven’t you heard that?”

He hadn’t. Luo Ren asked: “Who said that?”

“I did.”

Luo Ren put his hand to his forehead.

Shen Gun finally got to the main point: “In the letter left by Yin Erma, it says that Lu Ban spent almost the rest of his life observing these mechanisms that permeate the human world and the universe. He discovered a vast mechanism that, once formed, leaves no way out. Lu Ban called it the Seven Star Death Formation.”

Seven stars? Luo Ren felt a jolt in his heart, almost instinctively straightening up from where he was leaning against the car.

“Is it related to the seven ominous bamboo slips?”

Shen Gun gave a dry laugh.

“What happens next should be familiar to you. After discovering this secret, Lu Ban couldn’t eat or sleep properly. He sought out a good friend to discuss this important matter. This friend, whom we mentioned earlier, was the leader of the Mohist School, Mozi.”

“Although these two had previously quarreled over the city attack, as they say, fighting leads to mutual understanding. They admired each other’s abilities and became friends. Strangely, after hearing Lu Ban’s worried account, Mozi wasn’t surprised at all. He told Lu Ban that a great sage had glimpsed this heavenly secret over a hundred years earlier.”

Luo Ren had a thought: “Laozi?”

“Yes!”

Even in this situation, Shen Gun still had the mood to speak English. Luo Ren didn’t know whether to laugh or cry: “So what happened next? What is the Seven Star Death Formation?”

“I don’t know.”

“You don’t know?”

Shen Gun exclaimed, “How would I know? Yin Erma’s letter doesn’t say anything. The fact that I’ve told you this much is completely due to my wisdom and deductive reasoning over the past two days, understand?”

If Yin Erma truly had a secret, he should have considered the possibility of unexpected disaster and left a backup in a secure place—the item found on the main beam confirmed Shen Gun’s guess.

But that letter wasn’t written by Yin Erma. Shen Gun guessed that perhaps the original letter was on thin, fragile paper that had decayed, so Yin Erma had copied it word for word.

—Gongshu Zi advanced from craftsmanship to mechanical ingenuity, and then glimpsed the mysterious workings of heaven and earth, death formations and dead ends, with the Seven Stars at the forefront. Fearing great calamity, he urgently invited the Mohist leader. The leader smiled and said: The sage came before, and made arrangements early. After a night of discussion by candlelight, his mind was finally at ease. Now, seven secret keys remain. Whenever the seven stars shine continuously, the reader of this letter must hasten to deliver them beneath Cloud Ridge, to observe the Four Archways.

Shen Gun murmured: “I remember once, Yin Erma talked in his sleep, saying ‘keys, observe Four Archways.’ If I’m not mistaken, Yin Erma was just a resident of Yin Village, guarding the Eight Trigrams star-gazing platform, monitoring the movement of the seven stars. His education was average, and he might not have fully understood the short letter left by his predecessors. But he remembered one thing: once the seven stars shine continuously, he must arrange to send those seven keys somewhere beneath Cloud Ridge, to observe the Four Archways.”

However, where exactly beneath Cloud Ridge to observe the Four Archways was, they had no way of knowing yet.

While pondering this, Luo Ren ended the call.

Shen Gun had said earlier: You can’t simply deal with each bamboo slip as it appears. You need to think about why they’re appearing, what causes and purposes lie behind them.

Now, the heavy fog had finally lifted just slightly, but new mysteries immediately followed.

…

“Luo Ren!”

Luo Ren looked up to see Mu Dai hurrying out of the service center.

Mu Dai had received a call from her senior brother Zheng Mingshan—their master, Plum Blossom Ninth Lady, was gravely ill.

She was flustered and somewhat incoherent.

“Master is almost eighty years old and has been sick for a long time. This time it seems serious. Even the senior brother has gone back. He told me it might be time… Luo Ren, are you a fast driver? No, wait, I think the train would be faster on this route. I need to ask my senior brother to book a ticket for me…”

She questioned and answered herself, clearly very nervous and acting somewhat disorganized. Luo Ren took her hand to calm her down. Suddenly, she looked up: “Luo Ren, will you come with me?”

Luo Ren was taken aback.

Mu Dai explained: “Master is the person closest to me besides Hong Yi, sometimes even closer than Hong Yi—if it is time, I want her to meet you, because…”

Luo Ren hesitated: “Mu Dai, I still have things to do.”

Mu Dai half-opened her mouth, and a string of words suddenly stopped midway. She stared at Luo Ren blankly, as if not comprehending. A moment later, she quickly nodded: “Yes, yes, you have things to do too. Then I’ll go by myself… Oh, Chubby Cao, would you like to come with me?”

She turned midway to address Cao Yanhua.

Cao Yanhua had just paid and was holding a rooster, looking blankly at Mu Dai: “Go where?”

Mu Dai stomped her foot: “My master is seriously ill. You’ve taken me as your master, but whether you can be formally accepted into the sect depends on my master’s final approval…”

Cao Yanhua was also infected by her anxious panic and nodded repeatedly: “Go, go, go. Yes, let’s go.”

Yi Wansan poked his head out from the car and looked at Cao Yanhua: “Chubby Cao, I don’t think they allow live chickens on the train?”

“I’ll stuff it in my bag.”

“Do you think the scanners are blind? They won’t detect a chicken in your bag?”

At this moment, Huo Zihong came out from the supermarket with bags of shopping, not understanding how the situation had changed in the time she’d been shopping: “What’s going on?”

Luo Ren felt somewhat guilty toward Mu Dai but couldn’t explain, so he just tried to make conversation: “Has your master’s health always been poor?”

Busy sending her ID number to Zheng Mingshan, Mu Dai replied: “It’s never been very good.”

So, when she heard the news, although shocked, she was somewhat prepared.

“Then, shouldn’t you and your senior brother be by her side? You should visit regularly.”

Mu Dai sighed: “You don’t understand my master. She’s peculiar and doesn’t like company. Throughout the year, my senior brother and I only visit her on her birthday and during the New Year. Even then, if we stay too long, she chases us away…”

“Are you going just like this? Without any luggage?”

Most of Mu Dai’s belongings were still in Cao Village, but she didn’t seem too concerned: “You haven’t met my senior brother. He says that wherever you go, as long as you have money, an ID card, a phone, and a charger, you can just put them in a plastic bag and leave…”

Luo Ren drove Mu Dai and Cao Yanhua to the train station. Along the way, he wanted to talk to Mu Dai but didn’t know where to begin.

At the security check, Cao Yanhua’s live chicken became a problem as expected. The security officer refused to let him carry it on board. People queuing behind started complaining, and someone even offered Cao Yanhua a fruit knife: “You’re going to eat it anyway, just kill it now. Once it’s dead, you can take it on board.”

Cao Yanhua refused, telling Mu Dai to wait: “Little Master, I’ll go outside and give the chicken to Brother San to take back. Wait for me, okay?”

Only at this moment did Mu Dai consider the issue of Cao Yanhua buying a chicken: while she was getting a new phone, why had Cao Yanhua bought a chicken?

She couldn’t help but find it funny, but then remembered her master’s condition and felt inexplicably uneasy again. Luo Ren watched her and said, “Come here, Mu Dai, let’s have a hug.”

Probably a farewell embrace, Mu Dai smiled, reached out to wrap her arms around his waist, and as always, buried her head against his chest.

Luo Ren held her, bending down to kiss the top of her head, suddenly reluctant to let go.

He had thought he could accompany her back, but unexpected matters arose. Mu Dai could never have imagined he would be traveling across the ocean. With the leopard’s trail reappearing, the road ahead seemed treacherous no matter how he looked at it. If something went wrong, would this moment, this place, be the last time he ever saw Mu Dai?

A chill suddenly rose in Luo Ren’s heart.

In his daze, he heard Mu Dai sigh in his arms, saying: “Little Knife Luo, you have something on your mind that you don’t want to tell me.”