Chapter 127: Zhu Qiyu is a False Emperor

"Master Guo, is this really necessary? There are many errors and omissions in this orbital calculation guide; it is deeply flawed and absolutely not to be trusted!" Gao Mian hurriedly tried to dissuade him upon hearing the suggestion.

The work Xue Rui had written was disjointed and appeared hastily pieced together, lacking credibility. If Guo Gui failed to notice these issues and went so far as to seek advice from Xue Rui, it would be humiliating.

However, Guo Gui shook his head and said, "At the time, I thought Xue Rui was just spouting nonsense, so I never took his streamlining of the orbital calculations to heart. It was only after reading these drafts that I realized he had actually achieved something of substance. In my view, he has deliberately simplified some of the processes; to fully grasp the mysteries within, I fear I must consult him."

"This..." The few official supervisors looked at each other in dismay. Asking for advice from a student of astronomy who had only entered the Bureau two months ago? If this were to get out, wouldn't they be the laughingstock of the entire Bureau?

Noticing their hesitation, Guo Gui proposed, "Since it is inconvenient for you all to step forward, let me first test the depth of his knowledge. If he has truly invented a more concise algorithm, that would be a remarkable achievement, and there would be no harm in us learning from it."

"Let us follow Master Guo's suggestion. As the saying goes, among any three people walking, there is a teacher to be found. As long as we can improve our level of astronomical calculation, even if we lose a little face, it is of no great consequence," Xu Dun said with a nod.

Without further delay, Guo Gui left Xu Dun’s office and headed straight for the archives to find Xue Rui.

At that moment, Xue Rui was writing furiously. Seeing Guo Gui enter, he instinctively gripped his paperweight, his face full of vigilance.

"Student pays respects to Master Guo." Seeing that Guo Gui’s expression was calm and that he had no intention of reprimanding him, Xue Rui breathed a sigh of relief and bowed behind his desk.

Ignoring Xue Rui’s defensive posture, Guo Gui went straight to the point: "I have read your streamlined orbital guides. There are many obscure points in them, and I have come to ask you about these issues. Are you free now?"

Having a request, Guo Gui could not afford to put on airs and spoke to Xue Rui in a calm and conciliatory tone. He assumed that since he had lowered himself to ask, Xue Rui would naturally take the opportunity to set aside their previous unpleasantness.

To his surprise, Xue Rui shook his head: "Master Guo, please forgive me, but I have urgent matters to attend to and currently have no time to answer your questions."

"You..." Guo Gui’s face flushed red instantly. He had not expected such a blunt refusal from Xue Rui and felt a surge of indignation in his chest that nearly choked him. Staring at Xue Rui for a long time, Guo Gui suppressed his anger and said in a deep voice, "Then when will you be free? I can be at your beck and call."

He had already humbled himself enough; if Xue Rui didn’t want to offend him to the point of no return, he would surely grant him this face. Unfortunately, Xue Rui still shook his head: "Forgive me, Master, but I have no time for the next few days..."

"Fine, very well." Guo Gui now understood clearly that Xue Rui was deliberately humiliating him.

Just as he was about to turn and leave, he heard Xue Rui say, "Master, wait. The previous wager is over. I believe I have the slight upper hand. Does the Master acknowledge this result?"

Regardless of anything else, the results Xue Rui had calculated were correct. No matter how thick-skinned Guo Gui was, he could not deny this fact. Stopping in his tracks, Guo Gui looked at Xue Rui: "I am a man of my word. Whatever request you have, speak it. If it is within my power, I will not refuse."

"Master Guo is indeed a man of his word." Xue Rui said happily, "Tomorrow, I will be giving a lecture in the archives for the hereditary students on the new algorithm used in the orbital guide. Since you are a man of your word, could you please help me invite the various masters of the Bureau to attend this lecture?"

Guo Gui was slightly stunned and asked in confusion, "Since it is a lecture on a new algorithm, that is a good thing. You can just invite them yourself; why do you need me to step in?"

"I am afraid the masters would not do me the honor." Xue Rui gave a bitter smile. Officials of this era were obsessed with face. If these supervisors were to attend a lecture given by a mere boy like him in the archives, wouldn't they effectively become his students? This was something the supervisors could not accept.

Xue Rui had given this lecture careful thought. Guo Gui’s thirst for knowledge made him feel that the knowledge he possessed should serve its purpose in this era. In the process of streamlining the orbital guide, he had applied a great deal of modern mathematical knowledge, which could significantly advance the field of astronomy. Within the Bureau of Astronomy, the supervisors held the ultimate authority, and if Xue Rui wanted to promote a Western mathematical system, he needed their support. This lecture was a trap to draw them in; if they didn't come, the lecture would have little meaning.

Guo Gui was much more cautious this time, nodding only after a long pause: "I can only try my best. If some masters refuse to come, you cannot blame me."

"That is only natural," Xue Rui nodded hurriedly.

Glancing at the stack of papers covered in writing on his desk, Guo Gui said quietly, "I hope you do not disappoint me!"

"Please wait and see, Master," Xue Rui said with a confident smile.

After seeing Guo Gui off, Xue Rui continued working on his lesson plan. The content on the paper was based on his memory of the opening chapters of *Elements*. *Elements* was a mathematical treatise written by the ancient Greek mathematician Euclid around 300 BC, which had a profound influence on the development of mathematics in later generations. In history, this work was introduced to China in the late Ming Dynasty, translated by the famous scientist Xu Guangqi and the missionary Matteo Ricci.

Xue Rui’s original intention was to introduce Western mathematics in its entirety, but after thinking about it for a few days, he felt that ancient Chinese mathematics had its own established system, and a rash introduction might lead to rejection. He then thought of geometry, which was closely related to astronomy, reasoning that it would be easier to popularize starting from there.

To introduce geometry, one naturally could not bypass *Elements*. Although Xue Rui could not recall the entire content, with his mathematical expertise, he had no problem clearly explaining points, lines, planes, circles, and triangles. These foundations alone were enough for the students and officials of the Bureau of Astronomy to study. In this era, most of the best mathematical talent was gathered in the Bureau, providing a solid foundation for promoting geometry. Once these basics took root, they would inevitably spread to every corner of the Ming Dynasty, which would have far-reaching significance for social development.

The next day, when Xue Rui arrived at the Bureau, he brought a blackboard two meters long and one meter wide. He had specially commissioned a carpenter to make it a few days earlier, painting it with black lacquer and using white limestone from a pharmacy to make chalk. These items were, naturally, to facilitate his teaching.

Back when he first became the archive manager, he had found that the teaching style of the era was very rigid; the supervisors taught in a highly abstract manner, leaving many students confused and unable to grasp the point of the lessons. To change this and improve the quality of education, Xue Rui had come up with the blackboard and chalk. If he could write what he was teaching on the board, turning the abstract into the concrete, it would be much more helpful for the students' understanding.

When the blackboard was moved into the archives, the hereditary students were very curious. Xue Rui had someone bring over a table, placed the blackboard on the dais, and began to review his lesson plan. The students had learned yesterday that Xue Rui would be lecturing, so they arrived early. As Xue Rui finished his review, Guo Gui and Guo Heng entered the archives one after another.

In the back row of the room, several sets of tables and chairs had been prepared, specifically reserved for the supervisors. Xue Rui personally stepped forward to lead Guo Gui to his seat. Guo Heng had no objections to being seated in the back, but the subsequently arriving Dong Guan Zheng (Director of the East Office) Gu Bin and Xia Guan Zheng (Director of the Summer Office) Bu La complained repeatedly that Xue Rui was being disrespectful and questioned why they hadn't been given front-row seats. Xue Rui could only apologize repeatedly, claiming he had been inconsiderate and would certainly improve next time. Fortunately, Gu Bin and Bu La were easy-going and reluctantly accepted the arrangement.

Within the next two quarters of an hour, all the officials of the Bureau had arrived, with the exception of the Vice Director Gao Mian. Even Xu Dun came under the guise of an inspection to see what was happening.

Seeing that the time was right, Xue Rui stood on the dais and said in a clear voice: "It is a great honor to have you all here today. As you likely know, I have streamlined the orbital guide. Many processes were omitted, not out of intent, but because they involve a complex field of study which I call 'Geometry.' To understand the omitted processes in the orbital guide, one must grasp the fundamental knowledge of geometry. Now, I will start from the basics..."

Following this, Xue Rui used the chalk to write and draw on the blackboard as he spoke. This novel way of teaching allowed the students to intuitively understand the content, and even the supervisors sitting in the back listened with great interest.

The lecture lasted for an entire hour. The hereditary students felt little, but the expressions of the supervisors grew increasingly serious as they listened. Some of the concepts in geometry were mentioned in ancient Chinese mathematics, but they were scattered and fragmentary. Even someone as well-read in mathematical treatises as Guo Gui had never seen a book that was as thorough, concrete, and possessed such a complete logical system as what Xue Rui was presenting.

What Xue Rui taught today was very simple, but to the supervisors, it was as if a door to a new world had been opened, leaving them utterly captivated.

*Clang, clang, clang—*

The bell for the start of the Si hour rang. Xue Rui finished his final point, set down the chalk, and announced that the lecture had concluded.

Guo Gui, hearing this, hurriedly said, "Xue Rui, it is still early. Why not teach more? I still want to hear about the relationship between the sides and angles of a triangle that you mentioned."

Xue Rui gave a bitter smile: "Master, the previous session was during the students' self-study time, so it was fine for me to occupy it, but the next class must be taught by the Vice Director. It would be inappropriate for me to overstep my bounds."

Guo Gui then remembered that the hereditary students in the archive were taught by the supervisors in rotation, and it was now Gao Mian’s turn to teach.

"Very well. Next time you lecture, remember to notify me. I must not miss it," Guo Gui said as he stood up, still feeling unsatisfied. He had felt enlightened by Xue Rui’s lecture, and many new ideas were already forming in his mind. If he could attend a few more of Xue Rui’s lectures, he might gain even greater inspiration.

"Indeed, this geometry of yours has opened my eyes. Perhaps one day this field of study will shine brilliantly. I just wonder, did you come up with these things yourself, or did you see them in some book?" Bu La was quite elderly, but his mind remained sharp. The content Xue Rui had presented in this one hour alone was enough for him to realize its immense academic value. If this was a system created by Xue Rui himself, it was a truly remarkable achievement.

Xue Rui had already prepared an answer for this question. He could never be so shameless as to claim the entirety of geometry as his own creation. However, to avoid suspicion, he answered vaguely: "In truth, most of this knowledge was gleaned from other books, which I then summarized and made my own."

"And what is the name of that book?" Xu Dun asked, eager to follow up. If he could find such a book to study, he wouldn't have to lower himself to attend Xue Rui's lectures—a task that harmed the dignity of the Bureau Director.

"I happened to pick that book up on the street. Its cover had already been torn off, and after I finished reading it, I used it as scrap paper..."

"What?!" The supervisors cried out in shock, their eyes burning with a desire to see Xue Rui incinerated. That such an important book had been used as scrap paper was truly an offense against both man and god!

Xue Rui smiled bitterly: "It was my own youthful ignorance that destroyed such a work. However, the good news is that I remember most of the content. If there is sufficient time, I will write down the parts I remember. With you all to help check for errors and omissions, it should not be difficult to restore it to its original form."

"Sigh, then you must write it down as soon as possible, lest you forget it over time." Xu Dun shook his head helplessly and left with the other supervisors.

Once they were gone, Fan Yan and the others crowded around, holding their notes and asking about the parts they didn't understand. This intense enthusiasm for learning brought Xue Rui great comfort. He did not seek fame or fortune in spreading geometry; he only wanted more people to master it. And these hereditary students were the best vessels for that knowledge. With them bearing the burden forward, he would have a much easier time.

...

While the craze for "Geometry" was sweeping through the Bureau of Astronomy, the Wara army, after marching for days, arrived once again at the foot of Datong City.

This time upon arriving at Datong, Esen did not have Zhu Qizhen call out to the gates. Instead, he sent the Zhiyuan (Director) Archi, accompanied by the Ming traitor Xi Ning and the captured Ming interpreter and commander Yue Qian, to call out to the city.

The Datong Regional Commander, Guo Deng, had long known that Esen would come and had been waiting on the ramparts for some time. Seeing Archi and the others approach, Guo Deng shouted, "This is the territory and fortress of the Great Ming; you are not permitted to approach!"

Archi and his group stood their ground and had Yue Qian translate their words.

"General Guo! Grand Preceptor Esen says that the Wara have come to return the Zhengtong Emperor to the capital! The false emperor in the capital obtained his position illegitimately and will surely be abandoned by both men and gods! If General Guo considers himself a loyal subject, why not join with the Wara to drive the false emperor from power and restore the Zhengtong Emperor to his throne? If not, the Wara will take ten years if they must, but they will certainly kill the false emperor Zhu Qiyu, who has usurped the throne!"

The soldiers on the ramparts were shocked. They had not expected the Wara to return to drive out the new Ming monarch, Zhu Qiyu, and to harbor delusions of restoring Zhu Qizhen.

Hearing Yue Qian’s words, Guo Deng realized the situation was dire. The Wara were truly persistent, attempting to use the return of the Emperor to sow discord between the Zhu brothers. If Zhu Qiyu were truly provoked by the Wara’s instigation, he feared a great storm would arise within the imperial court.

On the ramparts, the soldiers began to discuss which of the two emperors would hold power if Zhu Qizhen were returned, and some even began to argue over it.

Guo Deng realized he could no longer remain indifferent. He ordered his personal guard to fetch a heavy bow, drew it with all his might, and fired an arrow directly at Archi and his men.