Seeking Truth with a Sword
Chapter 55 - 53 Variables

Chapter 55: Chapter 53 Variables

Li Ang raised his eyebrows in surprise. Song Shaoyuan and the others also frowned, looking displeased in the direction the voice had come from.

In the adjacent private room of the tavern, Qiu Jing, a Medical Officer from the Imperial Medical Bureau, a Taiji Palace waist token hanging by his side, couldn’t help but shake his head with a wry smile. He looked at his friend across the table, who was dressed as a Confucian Scholar, his face etched with indignation. 𝒻𝓇𝑒𝘦𝘸𝑒𝒷𝓃ℴ𝑣𝘦𝑙.𝒸ℴ𝘮

It was no wonder the middle-aged man opposite Qiu Jing wore a displeased expression. Laid out on the table between them was a vast paper map of Chang’an City, meticulously detailing its workshops, canals, wells, farmlands, streets, bridges, and even the Imperial Palace.

A map of Chang’an—or maps in general—ordinary citizens were not qualified to possess privately, or even handle, due to suspicions of treasonous intent.

But the Confucian Scholar in green harbored no such concerns. He was Tantai Leshan, one of the Masters in the Academic Palace who taught talismanic magic and engineering.

This map was a redesign blueprint for Chang’an City, conceived by Tantai Leshan and his students at the invitation of the Ministry of Industry, part of the Ministry of Supervision.

"Brother Leshan..."

Qiu Jing coughed lightly. He knew very well how much effort Tantai Leshan had poured into the redesign plans for Chang’an City recently. The plan had to account for the traffic, housing, drinking water, transportation, and city defenses for three million people. To maximize convenience for the city’s common people, Tantai Leshan and his students had surveyed every corner of Chang’an City. They repeatedly discussed, deliberated, experimented, and refined solutions for all identified issues.

This map was the culmination of Tantai Leshan’s tireless work for over a year. He found it hard to tolerate unwarranted criticism of it, especially concerning his proudest achievement: the planned water channel system intended to cover all of Chang’an.

However, those seated in the adjacent room were clearly scholars who had traveled from afar to participate in this year’s Academic Palace entrance examination. As a Medical Officer from the Imperial Medical Bureau and an Academic Palace Director respectively, they had inadvertently overheard the students’ conversation. This was already somewhat improper; confronting the students directly would be even more awkward.

"Mm."

Tantai Leshan nodded, signaling with his eyes to the servant standing in the corner. The servant understood immediately. Moving silently, he stepped out of the room, went to the adjacent one, and knocked to offer an apology.

"We are terribly sorry for disturbing the scholars’ feast," the servant said, clasping his hands, "but my master was simply wondering why building more drainage ditches would supposedly lead to more disease?"

"Ah, that... it’s nothing. We were just joking. Sorry to have disturbed your master." Yang Yu quickly sensed trouble brewing and, smiling, tried to gloss over it with a laugh.

The servant, however, whose hearing was evidently sharp, continued in a gentle tone, "My master says that the Academic Palace Disciples’ approach to scholarship is to respect the principles of Heaven and Earth, to hypothesize boldly, and to verify meticulously. There is no absolute truth or authority; rather, truth and authority exist to be constantly questioned and verified. If one feels something is illogical, one should point it out directly and discuss it rationally..."

Yang Yu’s eyelid twitched. There were many prominent families in Chang’an City, but not every one of them had servants capable of articulating the Academic Palace’s scholarly tenets with such eloquence and ease. No matter who was sitting next door, they spelled trouble.

For a moment, no one in the private room spoke. The atmosphere suddenly grew cold, leaving only the sound of Chai Cuiqiao gnawing on ribs.

CRUNCH. CRUNCH.

Perhaps Chai Cuiqiao’s bone-gnawing was too loud. Ji Linglang and the others unconsciously glanced at her, making her aware of the awkward atmosphere. She nervously continued to chew, but much more quietly.

CRUNCH. CRUNCH.

How mortifying.

"Um... I was the one who said that." Li Ang placed his chopsticks on his bowl and said casually, "The ’Inner Canon of the Yellow Emperor·Basic Questions·Yin Yang Manifestation’ says: ’The central region engenders dampness, dampness produces earth, and earth generates sweetness; the liver gives birth to the spleen, the spleen gives birth to flesh, and flesh gives birth to lungs; the spleen governs the mouth... Thinking injures the spleen, anger conquers thought, dampness injures flesh, wind prevails over dampness, sweetness injures flesh, sourness overcomes sweetness.’

"Since ancient times, the common people of the Central Plains have feared low-lying, damp places. Dreading moist, chilly, and shadowed environments, they all wished to live on higher ground. Consequently, land in the higher terrain of North Chang’an commands even higher prices than in South City. This instinctual fear among citizens of dampness and low-lying areas is, in fact, the result of accumulated long-term experience: people living in higher places are less prone to illness than those in lower areas. Everyone should be able to understand this point, right?"

"Hmm." Before anyone else could speak, Yang Yu nodded.

The higher real estate prices in North Chang’an were no secret. In fact, the Former Sui had built the Imperial Palace on the high ground in the northern part of the city precisely to avoid dampness. The "Treatise on the Origins and Manifestations of Various Diseases · Volume One · Wind Paralysis," compiled by the Former Sui Doctor Chao Yuanfang and others, directly states that the causes of wind paralysis include wind, dampness, and cold. According to the construction standards of the Former Sui Imperial Palace, it was possible to avoid wind and cold, but to avoid dampness, it was essential to build on elevated, dry land.

"Low-lying terrain, dampness, disease—these three have long been linked. But if one believes that low-lying and damp areas are the direct cause of disease, that would be like a constable arresting the bloodstained Broadsword found at a murder scene and calling it the murderer."

Li Ang stated casually, "Low-lying and damp areas are indirect causes of disease. The direct causes are water and vegetation. More precisely, it’s the mosquitoes that breed in stagnant water and among overgrown vegetation."

"Mosquitoes?"

Everyone present, including the servant, looked surprised. It was commonly believed, both by the populace and in medical circles, that illness was largely due to the invasion of ’external evils’ into the body. These external evils—factors that could harm body and mind—were understood to be wind, cold, dampness, dryness, fire, and ’pestilential qi,’ but they did not include mosquitoes.

"That’s correct." Li Ang nodded. "In the 22nd year of Jian’an, pestilence was rampant. Every family suffered the pain of stiffened corpses, and every household cried in mourning. Some families were wiped out entirely; others lost whole clans. This horrifying epidemic was malaria.

"And the cause of malaria... I recall my father mentioning a medical case. In a certain village, twin brothers had married twin sisters. The two couples lived as neighbors, worked in the same place, and ate largely identical meals each day. However, in the autumn, one couple died of malaria, while the other remained unharmed. If malaria is caused by external evils, then why would the other couple, with such similar physiques and nearly identical living environments, be unaffected?

"After careful investigation, the sole distinction between the two couples was this: the household that contracted malaria kept a water urn in their courtyard and usually drew water from it. The other household, however, fetched their water daily from the river. Yet, the water in the urn also came from the river. So, the only remaining difference was the mosquito larvae breeding in the stagnant water of the urn.

"When all factors in two scenarios are identical except for one, and the outcomes differ, that single differing factor is the variable responsible for the decisive effect. This is known as the control variable."