Life at fifty is monotonous.

Bai Zongnan, also known as Hualuo, was twenty-nine years old and a mathematics teacher by profession. The path he had chosen was entirely shaped by the influence of his father—himself a mathematics teacher. From childhood, Bai Zongnan excelled in mathematics: whether it was elementary-level Olympiad problems or the competitions of middle and high school, he always ranked first.

To his peers, mathematical formulas and intricate symbols, the tangled lines and complicated geometric figures, seemed daunting; yet in Bai Zongnan’s eyes, they appeared as captivating as masterpieces to an artist, just as romantic, just as enthralling.

Upon graduation, Bai Zongnan made a resolute decision: he would pass on his “art” to the next generation. He turned down the opportunity to study abroad and dedicated himself to the calling of teaching. With chalk and marker, he continued to express his “art” upon the blackboard, imparting his mathematical understanding and insights to his students without reservation. Watching class after class of students leave school behind and apply mathematical thinking in various fields filled him with a profound sense of happiness.

Yet the life of a teacher was monotonous. Though he loved his profession, the daily repetition wore on him, leaving him weary at times.

Sometimes, Bai Zongnan wondered: had he chosen differently, had he gone abroad for further study instead of becoming a teacher, would he now be a mathematician?

Elsewhere, mathematicians enjoyed a prosperous life. Perhaps, in another reality, he would be lounging on the sands of his seafront villa, counting the waves as they rose along the horizon, calculating the ebb and flow of the tides, deriving formulae that harmonized with nature, continuing his romance and artistry in a different form.

With this thought, Bai Zongnan sighed softly and entered his modest two-bedroom apartment.

Wait—what was that on the floor? A letter, slipped under the door?

Curious, he picked up the envelope and opened it. The words, printed in Song font on A4 paper, immediately caught his eye:

Dear Teacher Hualuo,

My name is Fei Hua, and I am the father of a child. My wife passed away early, and my child is now in the third year of junior high.

In past years, I was wholly absorbed in my career, neglecting both family and my child’s education. Now, my son Xiao Chai’s grades are declining across all subjects, especially mathematics. He ignores both my words and his teachers’, spending all his time addicted to computer games. I am at my wits’ end.

Here in City C, I have long heard of your outstanding teaching and your unrivaled mathematical expertise. Therefore, I write to you today, on the off chance, to invite you to visit my home and meet my son. If possible, I would very much hope you could become his tutor, help him improve his grades, and set him back on the right path.

As for remuneration, please do not worry. My years of hard work have not been fruitless—I will ensure you are well compensated.

You are cordially invited to visit my home this Saturday at 9 a.m. I would be deeply grateful.

On the reverse of this letter is a small token of my respect. Whether or not you accept my invitation, please accept it.

My address: No. 588, Jinxiu Avenue, Jinxiu Manor, City C.

Fei Hua

Fei Hua… The name sounded familiar.

Of course!

Bai Zongnan remembered now. Fei Hua was that self-made entrepreneurial genius who had often appeared on television in recent years; his wealth was renowned throughout City C.

Bai Zongnan turned over the letter and found a thin check affixed to it.

One hundred thousand yuan!

Jinxiu Avenue was famous as a wealthy district, home to the city’s elite. Bai Zongnan realized this was no prank.

And really, who would send a check merely for a prank?

A wave of hesitation swept over him.

What moved Bai Zongnan, perhaps, was not the check or even the sincerity in the letter, but rather a yearning within himself—a longing for another kind of artistic life in mathematics, a life of his own imagining.

Perhaps his life would change because of this letter.

On Saturday morning, as agreed, Bai Zongnan took a taxi to the address in the letter—Fei Hua’s manor.

The car sped along, and as they entered Jinxiu Avenue, the traffic thinned. The low buildings and apartment blocks vanished, replaced by clusters of villas and estates.

It seemed everything in the letter was true. A vague unease settled in his chest.

The taxi stopped in front of a manor, where a middle-aged man in a tailcoat was already waiting. He opened the car door for Bai Zongnan and nodded with a polite smile.

Bai Zongnan stepped out, feeling at a loss as he beheld the manor for the first time. He smiled back politely and was about to introduce himself when the man addressed him.

“You must be the guest our master invited. I am the butler of this estate. You may call me Afu. Please, come with me.”

Bai Zongnan was surprised, but followed him into the manor.

Stepping inside, Bai Zongnan felt he had entered a realm straight from his dreams. The rows of houses were all constructed with the golden ratio—the ideal proportions of length, width, and height. Between a pair of bronze lions, a pendant hung at the perfect center, like the vertex of a central angle in a circle.

Is that an isosceles triangle? No, wait—it’s an artificial hill.

Now this was art.

Silently, Bai Zongnan followed the butler to a villa.

The villa itself was a rare, perfect pentagonal prism. Every edge and every step leading to the door was calculated according to the Pythagorean theorem’s right-angle rule, giving the whole structure a sense of uprightness and poise.

In front of the villa stood several others.

The butler, Afu, stopped, turned, and nodded to Bai Zongnan, signaling that they had arrived. He walked toward the entrance, facing the six people assembled, including Bai Zongnan, and addressed them.

“Thank you all for accepting our invitation. On behalf of my master, I offer you our gratitude and welcome. You are all teachers hired by my master, but please don’t misunderstand—your assignments do not conflict; you are teachers of different subjects. It is now 8:47, a little over ten minutes before the appointed time. This is a good opportunity for you all to get acquainted, as you may be working together for some time. Oh, and my master instructed me to give you this once everyone has arrived.”

So Fei Hua had not invited just one teacher. That made sense—he had mentioned in his letter that his son’s grades were poor in every subject. What a difficult child, Bai Zongnan thought.

As he pondered this, he watched the butler distribute sheets of paper, handing one to each of the six teachers present.

Bai Zongnan accepted his and read:

Welcome to my home. Thank you all for your hard work. In a moment, the servants will escort you to the lounge, where coffee, milk, juice, tea, and all sorts of snacks will be available.

Teachers, my son is truly hopeless. I have hired tutor after tutor, but his grades remain abysmal. You are my last hope.

He used to do quite well in his previous class, but ever since he transferred schools, his grades have plummeted.

As the saying goes, “If a child is not taught, it is the father’s fault.” My son’s state is mostly my responsibility.

So I implore the most outstanding teachers to give your best efforts and help my child improve his grades. Rest assured, your rewards will exceed your expectations. I beg you!

After this brief introduction at the door, a homeroom teacher was chosen, and the teachers exchanged greetings and began to get to know one another.

At exactly nine o’clock, the villa’s doors opened. Guided by the butler, the teachers entered.

The villa’s grand hall was circular, with two elevators and a spiral staircase. A towering chandelier spanned all three floors. It was as magnificent as a palace.

A middle-aged man in opulent attire descended the staircase. His features were unremarkable, but he radiated authority. Upon seeing the teachers, he broke into a warm smile.

“I am Fei Hua. Welcome, teachers, to my humble home. Let us be frank: my son’s grades are terrible, and you know the reason you are here. I have drawn up a schedule, which I hope you will review.”

Bai Zongnan realized he was about to be caught in the same old cycle once again…