Chapter Nine: Essential Wisdom for Survival

Xiang Shan knew full well why Youji was so excited.

The boy was thrilled because Xiang Shan had promised to teach him some skills.

Xiang Shan admitted that revealing his identity was a bit of a gamble. He had even considered the worst-case scenario: that the concept of "chivalry" had been so thoroughly distorted in this era that "knights-errant" no longer held any prestige. In such a case, he might have had to knock Youji out and flee the town.

However, he truly lacked common sense regarding this strange era. He genuinely needed someone from this time to assist him. Furthermore, certain modifications involving the brain were impossible for him to perform alone. To regain his martial arts prowess, he needed a helper.

Youji was the only person Xiang Shan could trust for now. Having spent several months with him, he knew the boy was kind-hearted and intelligent. He also possessed enough curiosity to want to understand this world. In Xiang Shan's eyes, the boy had the potential to be cultivated into an assistant or even a disciple.

Xiang Shan had deliberated carefully before revealing his identity. After weighing the risks and rewards, he had chosen to be honest. Minutes ago, he had witnessed the expression on Youji’s face shift from shock and fear to relief.

"I saw that you were angry at how the workers were treated," Youji had said. "I believe you are a good person, a true knight-errant."

Subsequently, Xiang Shan asked where he could purchase parts and borrow a set of specialized tools. Youji then brought him to Dr. Schulz.

"Hmm, most of the parts you need are quite common. I have most of them here," Dr. Schulz said after glancing at the list Xiang Shan had prepared, then nodded. "However, a few of these are quite expensive. In that case..."

"Don't worry, I have a way to pay." Xiang Shan took a spine from the bag he carried. The spine shimmered with a silver-gray luster and felt heavy, not like an accumulation of calcium and protein; its density was closer to metal.

This was a relic left behind by Will Grand-Dog: a spinal column.

Humans could indeed grow such spines. This was something Xiang Shan had just remembered. In the 21st century, humanity had made massive strides in molecular biology and genetic engineering. Humans could use genetic modification to synthesize proteins containing metallic elements within their bodies.

If an individual used modified viruses to graft new gene fragments into their body and persisted in taking anti-immune drugs for a period to suppress the rejection between their original body and the new proteins, the cells composed of these proteins would gradually replace the primitive ones. This would eventually evolve a human from "Homo sapiens" into a new species.

This new hominid species, evolved from Homo sapiens, possessed a much stronger adaptability to cybernetic prosthetics. The metal-based proteins within their body formed natural wires and resistors, infinitely lowering the threshold for "brain-computer interfaces." Simultaneously, the cells' resistance to mechanical damage skyrocketed, and hardware implanted into the body would no longer cause necrosis in surrounding tissues.

Perhaps this was why Xiang Shan was able to wake up after being in a coma for countless years.

From a certain point on, the process of human prosthetic integration had galloped ahead like a wild horse.

Xiang Shan no longer remembered the finer details, but he recalled that in his era, the spine remained a crucial component. A metal-based spine served as a natural data transmission line with massive channel capacity, perfectly compatible with neural signals without requiring further adjustment. Many cybernetic modifications preserved the brain, cerebellum, medulla oblongata, and spine as a single unit.

And now, Will Grand-Dog’s martial artist prosthetic still utilized this technology.

Xiang Shan remembered that Youji’s mother, Yuliya, had sold spines. This item was still very valuable today.

Dr. Schulz was startled. "You want to sell this?" He looked at Xiang Shan’s stick-figure-like prosthetic. "You don't intend to use it yourself?"

Xiang Shan feigned indifference. "I don't have the medicine."

"Medicine?"

"You know... the stuff you need when replacing a spine... what was it called?" Xiang Shan asked tentatively.

After accepting metal-based genetic fragments, cells gained increased resistance to apoptosis, and receptors on the original cell membranes were rewritten, making the new humans largely immune to earth-native viruses. Additionally, the rise in body temperature made humans immune to most old germs, fungi, and parasites. But this did not mean there was no rejection. Using someone else's spine would still trigger a reaction.

Of course, this was based on the era in Xiang Shan's memory. He didn't know how much technology had progressed since he went into his coma. Youji didn't know the answer to such technical questions, so he had to test Dr. Schulz.

Dr. Schulz nodded. "Indeed... 'Anti-Messenger Soaking Agent' is quite hard to come by."

He didn't harbor much suspicion. After all, ordinary people rarely needed to replace their spines.

"Yes, yes, Anti-Messenger Soaking Agent!" Xiang Shan nodded, pretending to have a sudden realization—fortunately, he was currently faceless and skinless, and his voice synthesizer was a cheap, emotionless model, so he didn't need to act.

*Anti-Messenger Soaking Agent... a term I’ve never heard of. Is 'messenger' related to messenger RNA?*

Xiang Shan was an engineer, but he vaguely remembered a biologist friend discussing related topics. *The Central Dogma: DNA transcribes genetic information into messenger RNA, which is then translated into long peptide chains; the peptide chains fold via organelles into proteins... Reverse transcriptase? No, that shouldn't be it... Is this process now reversible?*

It seemed technology had indeed advanced, Xiang Shan concluded. In his era, aside from exceptions like prions, other life activities basically followed the "Central Dogma" of genetic expression. It was nearly impossible to reverse such life activities within the cells of a higher organism.

"However..." Dr. Schulz flipped the list to the end and looked it over. "I really don't have these parts... these specifications shouldn't be applicable to prosthetics, should they? And the last item, iron sheets with a thickness of no more than one millimeter and a width of less than three centimeters? If you want to find these, you’d best go to the scrap collection bin at the east end of town."

Xiang Shan explained, "These are for making some... auxiliary tools."

"Looking at this list, you haven't had professional training, have you?" Dr. Schulz shook his head. "Many of your specifications are written in non-standard ways. I don't know what kind of prosthetic you plan to build, but professional martial artist prosthetics are rare and hard to come by. I don't want you to waste hard-won, good parts. How about this? Would you like to go online and check some design blueprints?"

"Go online?" Xiang Shan was startled. He remembered that the internet had once vanished due to war. He truly hadn't expected this dilapidated-looking world to still have network signals.

"Our town is a bit run-down and lacks public network signals. However, I have a private one set up at home. If you sit in the center of the living room, you should be able to receive it. I can give you a one-time access password..." He paused here. "However, it’s best if you don't download things randomly, and don't open previews for holographic signals..."

Xiang Shan was indeed tempted. But in the end, he shook his head. "No, Doctor, thank you for your kindness. The internet must be very expensive; I cannot take advantage of you."

"That spine has already earned me quite a bit," Dr. Schulz patted Xiang Shan’s shoulder. "Besides, you saved my town; I truly owe you my thanks."

"No, I’m not used to accepting favors for nothing. If I have a need, I’ll come back to borrow your network." Xiang Shan refused Dr. Schulz’s offer once more.

Dr. Schulz did not insist. He quickly gathered the parts Xiang Shan needed and lent him a set of professional biological tissue surgical tools.

After confirming that Xiang Shan had walked away, Schulz went upstairs. The mayor was in a room on the second floor.

"Uncle, he didn't go online." Schulz looked puzzled. "Why did you want me to remember to invite him to go online?"

Dr. Schulz truly didn't understand his uncle’s request, but he had complied nonetheless. His uncle was the most knowledgeable person in town, having traveled far and wide in his youth and learned of various secrets.

"Dresden..." the mayor called out to Schulz. "First, turn off the network."

Schulz nodded and issued a command through his brain-computer interface to disconnect the home network. He was used to saving on network fees anyway.

"Do you know, Dresden?" The mayor seemed to be reminiscing about the past. "When I was young, I offended an official and had to leave my hometown."

Schulz nodded. "Indeed, but you were lucky; that official died later..."

"He was assassinated by a knight-errant," the mayor said after a moment of silence. "That knight-errant was someone I summoned..."

"What?" Schulz shrieked. Colluding with a knight-errant was a grave crime violating the Dyson Principles!

"I didn't collude with them. I just happened to meet a knight-errant in the wilderness and requested help," the mayor scoffed. "Your grandfather, my father, once told me that these thugs—knights-errant—are actually quite easy to utilize. As long as you appear humble before them, they won't give you trouble. On the contrary, they will assassinate officials they deem guilty for the sake of some twisted sense of honor. They are very easy to use. This is a very important survival wisdom for us."

Schulz exclaimed, "You never told me that..."

"That was before... the fewer people who know this secret, the better." The mayor paused. "But now, the situation is different. The tax collector only took eighteen infants, below the standard ratio. We don't know how he plans to deal with us. Perhaps we have no choice but to rely on the power of a 'knight-errant'."

Schulz immediately understood. "You mean... Shan is a knight-errant?"

"I don't know what Mr. Shan did before he lost his memory, but I know that all knights-errant share a habit: they don't connect to the network casually. I spent a few days with one once; they always undergo lengthy preparations before going online," the mayor said in a low voice. "Whether Mr. Shan is a knight-errant, I’m not sure. However, he is certainly capable of fighting—especially now that he has obtained that martial artist prosthetic."