Mid-April.

The letter was sent from Provincial Normal University.

The handwriting on the envelope was elegant—each stroke neat and precise, as if printed. When Niannian saw the sender's name, her fingers paused.

Su Xueqing.

This name occupied a unique place in her memory.

A teacher at Provincial Experimental Middle School. Someone who had helped her during middle school. Later, she went to teach at Provincial Normal University.

Niannian opened the letter.

The letter was not long. One and a half sheets of letter paper, the front fully written, and three lines on the back.

"Niannian: Seeing this letter is like seeing you in person.

I learned from Professor Han that you won the silver award in the National Youth Mathematics Talent Selection, and I am happy for you. You have walked from Chengjiawan to where you are today, and every step has not been easy. When I first saw you at Provincial Experimental Middle School back then, I felt there was something about you—not just intelligence, but that drive of 'no matter what, you must keep moving forward.'

This year, I applied for a master's degree at Provincial Normal University, with a focus on Mathematics Education. You know my advisor—Professor Han Zhengyuan. Yes, that is Han Zimo's father. What a small world.

Professor Han has mentioned you to me. He said that you use elementary methods to solve problems that can only be handled by higher mathematics, a capability that is extremely rare among your peers. He also said that your weakness lies in your knowledge base, not your thinking—filling the knowledge gap is just a matter of time.

Niannian, I have something I want to tell you. Not as a teacher, but as someone who has walked the same path—

Academia is a long journey. Do not rush, take it slow.

You are fifteen years old now. You think you must finish all your battles by fifteen, but in reality, the road ahead of you is still very long. Those gaps you cannot catch up with for now, those bits of knowledge you cannot fill immediately, are not the end. You only need to maintain your direction and keep your rhythm.

Time is on your side.

Xueqing. April 8, 1986."

Niannian read the letter twice.

After finishing the second reading, she folded the letter and put it back into the envelope.

Then, she rummaged through her drawer for a roll of clear tape and took out the sheet of paper with the key sentences—not the whole letter, just that last paragraph.

She taped that paragraph onto the wall above her desk.

It was taped right next to "Niannian's Rules" written by Song Wanqing.

The two pieces of paper hung side by side.

One was from her mother. One was from her teacher.

One looked after her body. One looked after her mindset.

Niannian sat at her desk, looking at the two papers on the wall, her fingers tapping unconsciously on the tabletop twice.

Fifteen years old.

At fifteen in her previous life, there was nothing on her desk. To be precise, she didn't even have a desk.

She would hunch over a low stool by the stove to write, her fingers frozen stiff, with the crackling of firewood and Wang Guifang's scolding sounds beside her.

At fifteen in this life, her desk had notes, test papers, the higher mathematics notes borrowed from Han Zimo, and the Elementary Number Theory book given by Elder Zheng.

On the windowsill sat half a cup of cold water, and beside it was the thermos that Song Wanqing prepared for her every morning.

She touched the corner of the letter paper on the wall.

"Do not rush, take it slow."

To be honest, she could not "take it slow."

She had a clock in her heart that had been ticking since the day she was reborn.

Tick-tock, tick-tock, reminding her that time was limited, opportunities were limited, and she had missed too much in her previous life.

But that sentence Su Xueqing said—"Time is on your side"—made the string in her heart that had been stretched for too long loosen just a little.

It was not slacking off. It was letting out a breath of relief.

When she returned home in the evening, Niannian mentioned Su Xueqing's letter to Song Wanqing.

Song Wanqing was sewing the ear of a plush dog. Hearing the name "Su Xueqing," her hand stopped.

"Teacher Su?"

"Yes. She is studying for her master's at Provincial Normal University."

Song Wanqing's eyes brightened: "Teacher Su is a good person. When you were at Provincial Experimental Middle School, she helped our family quite a lot."

The images of Su Xueqing in her memory were still quite clear. After all, she was one of Niannian's most crucial supporters during middle school—this memory belonged to the eighty percent that had recovered relatively early.

"It is good that she is studying for her master's." Song Wanqing lowered her head and continued sewing the plush toy, a smile on her lips, "Good people get good rewards."

Niannian sat beside her and took out that Elementary Number Theory book, turning to the fifth chapter.

The mother and daughter, one sewing, one reading.

From the shed came the sound of Gu Yanqiu welding—a "zzzt" sound, and the light of the sparks flashed through the gap in the curtains.

Three people. Three things.

All moving forward.

But as one walks some paths, one will encounter pits.

The pit is already on the road.