Chapter 132: Great Wisdom Turns Out to Be Monk Yixing

To Ye Chang's surprise, the problem only baffled Zhang Xiu for a short moment before he pulled a handful of bamboo sticks from his travel pouch and, with a few swift moves, reported the exact answer.

Ye Chang looked at him with sudden amazement.

His gaze toward Zhang Xiu shifted entirely.

The problem of chickens and rabbits in the same cage was merely introductory, but this drainage and filling puzzle was far more difficult. In this era, anyone capable of solving such a problem could truly be called a mathematician.

What mathematicians were there in the Tang Dynasty?

At least in Ye Chang's memory, he could not recall any prominent mathematicians of the Tang Dynasty, let alone this Zhang Xiu... Perhaps in the currents of history, he had died in obscurity, leaving no trace behind?

China had abounded with wise men and sages since ancient times, yet only a small fraction of them were known to posterity. The vast majority vanished into the long river of history just like ordinary people.

"Are there any more puzzles?" After finishing this problem, Zhang Xiu was eager to try his hand at more. "Can you make them harder?"

Ye Chang pondered for a moment, then stated a sequence of numbers while leaving a gap in the middle.

This was a permutation and combination problem, requiring the solver to find the underlying pattern of the sequence and then deduce the missing numbers based on that rule.

Just like the previous two problems, this one tested logical thinking skills.

This time, Zhang Xiu pondered for a long time, shuffling his counting rods back and forth for quite a while before finally reporting the correct numbers.

"Splendid, absolutely splendid!" Jia Maoer had originally looked down upon this lean and sharp-featured man, but now he could not help pressing his thumbs up in praise.

He was a shrewd observer, and it was obvious that Ye Chang intended to recruit this man. Since that was the case, he naturally had to offer assistance from the sidelines.

"In the art of calculation, I am afraid no one in the world can compare to Master Ye. Tut tut, magnificent!"

"My late uncle and Lord Liang far surpassed me. They could calculate more than just these; even the movement of the sun and moon and the shifting of the stars were within their calculations."

At Zhang Xiu's words, Ye Chang merely smiled it off, recognizing it as obvious boasting, but Jia Maoer beside him frowned.

Unlike Ye Chang, whose total time spent in Chang'an didn't even add up to two months, Jia Maoer had lived in Chang'an for over thirty years. Many historical anecdotes and figures unknown to others were familiar to him.

"Wait a moment. You just said your uncle was Great Wisdom Master Chan? Could he possibly be... Master Yixing?"

Yixing.

This name made Ye Chang's expression change in astonishment.

If one spoke of the most renowned Tang Dynasty astronomers remembered by later generations, aside from Li Chunfeng, it would surely be this monk Yixing. However, Ye Chang was curious: Yixing was the religious name of this Tang astronomer, so what was Great Wisdom?

"He is indeed my late uncle."

"Great Wisdom is Yixing?" This time, Ye Chang no longer concealed his profound shock.

"Yixing was his religious name, and Great Wisdom is the posthumous title bestowed by the Emperor," Jia Maoer said in a low voice. "As for that Liang Lingzan, I remember him now as well. He was once a scholar awaiting decrees at the Hall of Assembling Worthies, and possessed craftsmanship as miraculous as Heaven's own creation alongside Master Yixing."

At this moment, Ye Chang vaguely recalled that Yixing, together with a man named Liang Lingzan, had constructed the Water-Driven Armillary Sphere—a device that utilized the earliest form of an escapement mechanism.

What an escapement mechanism meant was something others might not know, but Ye Chang understood it very clearly: clocks.

And what clocks would mean in an era that relied on hourglasses for timekeeping—what they would mean for the great age of navigation Ye Chang wished to develop, and even for precise military operations—was immeasurable.

Even just for making a fortune, the watchmaking industry would become an endless stream of wealth.

He had never expected that this lean Zhang Xiu would actually be the nephew of Yixing.

Yixing had passed away more than a decade ago at the age of just over forty, and Liang Lingzan, who had collaborated with him, had also long since departed this life. That was why Jia Maoer had not immediately made the connection.

Upon closer inquiry into Zhang Xiu's background, he was indeed Yixing's nephew by blood. Although Yixing had claimed Zhang Gongjin, the Duke of Tan and one of the twenty-four meritorious officials of Lingyan Pavilion, as his great-grandfather, he was actually only a distant grand-nephew of Zhang Gongjin's clan. Their Zhang family, having multiplied down the generations, remained prominent officials in the Tang Dynasty, and Yixing's attachment to their lineage was customary for the times.

As Yixing's clan nephew, Zhang Xiu had followed by Yixing's side as a young novice monk after Yixing gained the favor of Li Longji and his fame spread throughout Chang'an. Influenced by Yixing, he developed a deep passion for mathematics and mechanics. Following Yixing's death, he continued to follow Liang Lingzan. But after Liang Lingzan passed away as well, he drifted about with no one to rely on, making a living through the relief of his clansmen while stubbornly continuing his bitter study of mathematics and calendrical science.

"Where are the artisans who originally built the Water-Driven Armillary Sphere and the Ecliptic Ring and other such devices now?" Ye Chang suppressed his inner excitement and asked calmly.

Those men were the most precious treasures of this era!

In this age, anyone who could write poetry or paint was considered a talented scholar, yet these scholars could only create spiritual wealth. While they were indeed immortalized, they contributed little to the overall progress of society. Ye Chang certainly respected them, but if he had to choose, he would still prefer to recruit more artisans to research mechanics together.

"Most of those artisans belong to the Directorate for Palace Buildings..." Zhang Xiu's single sentence dashed Ye Chang's hopes.

"This Directorate for Palace Buildings, what is it about?" Clinging to a glimmer of hope, Ye Chang asked Jia Maoer. He knew that the Directorate for Palace Buildings was the agency governing artisan affairs, but he still needed to ask someone of this era about the details.

Jia Maoer was familiar with Chang'an and happened to know the Directorate for Palace Buildings well. As he explained in detail, Ye Chang nodded repeatedly.

It turned out that the Directorate for Palace Buildings and the Directorate of Palace Armament were the two central government agencies managing artisans, largely staffing them with convicts. The number of artisans under their jurisdiction was massive. The Directorate for Palace Buildings had fifteen thousand craftsmen, while the Directorate of Palace Armament had nineteen thousand eight hundred and fifty, not even counting the artisans controlled by local prefectures and provinces. Moreover, both directorates actively trained new artisans. The completion time for every apprentice was strictly regulated; their administrative codes stipulated that an apprentice must finish his training anywhere from four years to forty days at the longest, or face punishment. Craftsmen specializing in complex handiwork such as gold, silver, copper, and iron carving and inlay had a four-year apprenticeship, while garment makers and hat makers had a nine-month period.

Ye Chang knew that artisans belonging to the Directorate for Palace Buildings and the Directorate of Palace Armament had no personal freedom whatsoever. He contemplated acquiring a batch of artisans through Princess Yuzhen, but immediately dismissed the notion: Princess Yuzhen also had her own selfish motives, the ball-game market being a prime example. Artisans obtained through her would have questionable loyalty to anyone else; it was entirely possible that as soon as he developed a new technique, Princess Yuzhen would summon the craftsmen away.

He didn't mind cooperating with Princess Yuzhen or other members of the Tang imperial clan to start new industries—he also needed the industrial bourgeoisie to grow rapidly and replace the agrarian bourgeoisie to attain mainstream status. However, the prerequisite was that the other party's interests were deeply bound to his own, much like the knight-errants brought by Jia Maoer. Figures like Princess Yuzhen had too many independent interests, and at times their objectives would conflict with Ye Chang's. Therefore, until he possessed sufficient self-protection capabilities, Ye Chang would not consider launching new cooperative projects with her.

"There's no way to invite them over..." Thinking of this, Ye Chang scratched his head and sighed.

"If Lord Ye wishes to invite them, it is not entirely impossible." Zhang Xiu suddenly spoke up again.

"Oh?"

"The artisans who originally built the Water-Driven Armillary Sphere all had their names engraved upon it and rendered great service. Later, the Emperor issued two major amnesties successively, and their names were removed from the criminal registries and reclassified as miscellaneous commoner households."

Hearing this, Ye Chang was overjoyed.

The household registration system of the Tang Dynasty was very strict; once someone was on the criminal registry, there was no hope of getting off it. Miscellaneous households were different. Although miscellaneous households were still craftsmen and barred from taking the imperial examinations, at least relocating or being hired out was not as troublesome as being on the criminal registry, and it did not require navigating deep bureaucratic channels.

"Do you know them?"

"In the past two years, since Lord Liang passed away, my interactions have decreased. But back when Lord Liang was still alive, I often went to see them."

Ye Chang was extremely satisfied. This Zhang Xiu was not only a research-oriented talent himself, but he also possessed such vital connections among the artisans!

"I have a new book recently; have a look at it first."

Without directly discussing further matters with Zhang Xiu, Ye Chang called Chunming and instructed him to retrieve a manuscript from his study. Shortly after, Chunming ran over and handed the manuscript to Zhang Xiu.

Zhang Xiu opened it, and on the frontispiece, a lengthy piece of prose was copied out.

Qu Yuan's *Heavenly Questions*.

Although Zhang Xiu's interests did not lie in poetry and literature, he was very familiar with Qu Yuan's *Heavenly Questions*. His clan uncle, Yixing, had once expended considerable effort trying to answer the puzzles posed within it.

Zhang Xiu looked at Ye Chang in surprise. Could it be... that Ye Chang had actually found answers to these questions that had stumped so many brilliant minds?

Ye Chang smiled.

During his time teaching in remote mountain regions in another life, Qu Yuan's *Heavenly Questions* and Liu Zongyuan's *Heavenly Replies* were also the texts he recited to dispel his loneliness.

The era in which Liu Zongyuan lived was not far behind the present, and anyone reading Liu Zongyuan's *Heavenly Replies* without knowing the context would truly find it shockingly heresy-inducing, bound to bring severe official punishment upon the author.

However, although Liu Zongyuan had been demoted, it had nothing to do with these *Heavenly Replies*.

For the sake of caution, Ye Chang had not brought out those *Heavenly Replies* just yet. Therefore, when Zhang Xiu turned to the second page, it shifted to the subject that truly interested him.

"Heat and Cold?"

The second page discussed heat and cold. Based on the empirical knowledge summarized by carpenters and others, Ye Chang pointed out that furniture warped during winter and summer precisely as a result of thermal expansion and contraction. He then boldly proposed that the space surrounding human beings was not a vacuum, but filled with air; air expanded and became lighter when heated, acting just like a boat floating on water to lift a Kongming lantern. Once the candle flame in the air extinguished, the air cooled down again, causing the Kongming lantern to descend.

"After parting ways in Chang'an, I pondered this problem, guessed this conclusion, and then conducted several experiments which verified it," Ye Chang added.

"So... so that is the principle. There is air all around us?" Zhang Xiu thought for a moment. "Indeed, there must be air. What we inhale and exhale are both currents of air. If an empty cloth bag is submerged in water with a single hole poked in it, bubbles will escape as well. Furthermore, the balls used in the capital are also inflated by pumping air into pig bladders..."

In an instant, he entered a state of complete absorption and began muttering to himself once again.

Ye Chang knew he would be lost in this book. This was a textbook he had originally compiled to teach his students some basic physical common sense. As for Qu Yuan's *Heavenly Questions*, it was merely meant to spark the students' enthusiasm for exploring the unknown world; if any literati criticized him for teaching unorthodox subjects, he could use that as a pretext to brush them off. He had never expected that before the textbook manuscript had even been compiled for many pages, he already had a reader.

"Brother Maoer, I'm afraid I must trouble you to make a trip back to Chang'an." Ye Chang turned to Jia Maoer. "As for those artisans, invite as many as you can for me. If you cannot get the men themselves, their sons, nephews, or apprentices will do. As for their wages, within a hundred guan per year, you have full discretion."

"A hundred guan?" Jia Maoer was astonished.

These artisans working for the court received nothing more than basic rations, and wages were completely nonexistent. Whenever they took on outside odd jobs on the side, they were heavily exploited from all directions. If they were truly offered a hundred guan, they would undoubtedly come crying and shouting to join.

"Yes. Control the numbers so as not to stir up too big a commotion; this matter must be done in secret." Saying this, Ye Chang gave Jia Maoer a meaningful look.

Jia Maoer understood and nodded.

Although those artisans had been amnestied and reclassified as miscellaneous commoner households, their names were still registered with the Directorate for Palace Buildings and the Directorate of Palace Armament, and they could not easily leave Chang'an City. Ye Chang's implication was for him to use extraordinary methods.

With tens of thousands of craftsmen, a dozen or so running off was something that happened every year, and the court wouldn't investigate too closely. Naturally, this would involve bribery, sneaking through checkpoints, and other illegal means—methods that were second nature to Jia Maoer.

"The settlement of these artisans..." Ye Chang pondered. These craftsmen could not be housed in Wolong Valley; on the one hand, too many eyes were fixed on Wolong Valley, and on the other hand, Wolong Valley was spatially restricted. If a school were established there, there truly wouldn't be any open land left to accommodate these artisans.

It seemed necessary to expand further into Mount Fufu.

Ye Chang was not particularly anxious about this. Mount Fufu was a branch of the Taihang Mountains, which had once harbored tens of thousands of bandits, and even now, wild folk still lived within the mountains. He could open up another valley not far from Wolong Valley to serve as an artisan district. Then, guarding it strictly would double as a practical training exercise for the youths of his clan, teaching them how to handle real-world matters.

He had long since harbored the notion of expanding Wolong Valley, so as he pondered, a location came to mind: another valley about four miles away from Wolong Valley, perfectly nestled between the mountains and the Wuze Marshes. With the lake on one side and the mountains on the other, transportation was highly inconvenient, making it ideal to set up a single ferry crossing for the sake of secrecy and defense.

Just as Ye Chang was mulling over these details, Zhang Xiu suddenly leaped forward with movements swifter than the monk Shanzhi. He grabbed Ye Chang by the arm: "What's next? What's next? Are there more?"

"Ah?"

As it turned out, the book Ye Chang had compiled over the past few days only amounted to a few pages. Zhang Xiu had finished reading them instantly and found himself unable to stop, naturally rushing over to pester Ye Chang for updates.

Ye Chang paused, then laughed.

The other man's expression made Ye Chang realize that this fellow had boarded his ship.

Since he had boarded, he needn't think about getting off.

Just as Ye Chang was about to further secure Zhang Xiu's stay, a commotion broke out outside. Immediately afterward, a single horseman came galloping furiously toward them.

The Kunlun slave Wuguli chased wildly behind the rider. Although he was swift on his feet, he couldn't outrun a horse, and the distance between them kept growing.

The horse came to a halt with a dramatic neigh right by Ye Chang's group. Shanzhi's wax-tipped pole was already on the verge of tapping the rider between the eyebrows when the passenger vaulted down from the saddle, bowed deeply toward Ye Chang with a voice choked with tears: "Lord Ye, save me!"