February 15th, New Year’s Eve.

When Chinese people welcome the New Year, there are many activities, such as sprinkling flowers, pasting window decorations, and even making dumplings...

But these activities are not available at all in Lao Lin's place.

When Lin Chaoxi got up in the morning, Old Lin just came back from buying groceries.

There were already children in the alley setting off firecrackers, with the crackling sound in the background. She ran out excitedly to look through the vegetable basket and found that Lao Lin had only bought a fish, bean sprouts, and a bunch of green vegetables.

Lin Zhaoxi: “…”

"What's that expression on your face?"

"Dad, it's New Year's Day, don't you want to eat something?"

"With surplus every year and prosperity as you wish, what else do you need?"

"Like, thriving, successful in studies?"

"You are already good enough at studying, you don't need to be better."

Lin Zhaoxi: “…”

As Lao Lin was about to carry the vegetable basket into the kitchen, Lin Chaoxi quickly put on her cotton jacket and pushed Lao Lin out of the house: "Let's buy some more. I want to eat braised beef!"

"I'm already fat."

"Don't worry, you won't be unable to get married." Lin Chaoxi responded with a smile.

The market was bustling with people, as many families were preparing ingredients for the New Year's Eve dinner.

With bacon hanging horizontally and various bright vegetables and fruits, the market is probably the place that has the most festive atmosphere in her mind.

She said she wanted to go out to buy something delicious, and she also wanted to accompany Lao Lin, so she didn't buy anything. But when she passed by the fried chicken stall, the aroma was really tempting, so she pulled Lao Lin and said she wanted to eat some fried chicken legs.

"Master Lin, have you brought your daughter here again?" the stall owner greeted him warmly. "Your daughter looks smart. How many legs do you want?"

"Hello, boss. Three, please." Lin Chaoxi looked at the price tag of 6 yuan each, and three was exactly 18 yuan. "I'll take two and you take one," she said to Lao Lin.

Lao Lin took out 20 yuan, and the stall owner was busy handing them chicken legs. But when he was giving the change, he flipped through his change bag and said, "We have so much business this morning, I don't have any change. Master Lin, do you have any change?"

"no."

"Then come back after the New Year and I'll give you the change."

"Well..." Lao Lin didn't say anything.

Lin Chaoxi was chewing on a chicken leg, feeling a little happy in his heart: "Dad, the boss just now seemed to be waiting for you to say 'no need to look for it'."

"How can I not look for him?" Old Lin said angrily, "I'll be waiting for him on the first day of the new year."

"But he just praised me for being smart."

"Do you know what 'looking smart' means?"

"Has my knowledge infected my temperament?"

"No, usually Mr. Li compliments others on their good looks."

Lin Chaoxi turned and left.

"What are you going to do?" Lao Lin called her.

"Go wait in front of his stall. Someone will definitely pay with change soon. I'll go get the change back from him!"

If it were another parent, they might not accompany their child to go crazy. But Lao Lin was different. Lao Lin was more idle. So when the two of them stood in front of the fried chicken stall, each holding a chicken leg and waiting for change, the boss still broke down. He quickly took out two coins from the money he collected and stuffed them into Lao Lin's hand: "Master Lin, I owe you money. I'm so sorry."

"It's okay." She and Lao Lin said at the same time.

After walking around the market, thinking of Lao Lin’s cooking skills, Lin Chaoxi decided to buy only cooked vegetables.

There was not much that the two of them could eat, so in the end they only had a small bag of braised beef and cold seaweed.

On the way back, Lin Chaoxi had already finished the last chicken leg. Every household in the alley was in the atmosphere of the New Year, some were putting up couplets, some were cooking, but when Lin Chaoxi and Lao Lin walked together, they inexplicably did not have any enthusiasm and excitement that should be there during the New Year, but were very calm. And she suddenly realized that if she didn't speak, Lao Lin would not take the initiative to ask her anything.

In order to ease the cold atmosphere between father and daughter, Lin Chaoxi found a topic to talk about: "Why don't you ask me how I'm doing in the training team?"

"What's the good question?" Lao Lin asked back.

"Then why are you so confident in me?"

"Do you want me to tell you that I am very confident in my daughter, or do you want me to tell you that your team teacher often calls me to report you?"

"I don't want to hear any of it." = =

After walking a few more steps, Lin Zhaoxi looked at Lao Lin. Just as she was about to speak, Lao Lin spoke first: "Comrade Lin Zhaoxi."

"exist!"

"Has your relationship with your old father reached the point where you can't find a topic to talk about?"

Lin Chaoxi felt that there was simply no conversation to have that day. She had finally wanted to be a filial daughter, accompany her father to buy groceries and chat, so that Old Lin could feel the joy of family, but she found that no matter what they talked about, she was the only one who was killed by Old Lin in seconds.

The spring sunshine was warm. As soon as she got home, Lin Chaoxi prepared to go back to her room to continue doing her homework, and treated Lao Lin, who didn't want to chat with her, with a cold attitude.

Unexpectedly, as soon as she entered the house, Comrade Lao Lin, who was sitting on a stone bench in the courtyard, called her while picking bean sprouts: "Such nice weather, why don't you come out and accompany Dad?"

Lin Zhaoxi: "I don't!"

"You said it yourself, you need me to pay attention to your current academic situation."

Ten seconds later, Lin Chaoxi was sitting upright in front of Old Lin, holding books and textbooks.

"How is your study going?" asked Lao Lin.

Lin Chaoxi was silent.

"What's wrong?"

"I'm trying to think of a way to describe it, but no matter how I describe it, you'll say it's not precise enough."

"That makes sense." Lao Lin threw the selected bean sprouts aside. "Mathematics in college is quite difficult, isn't it?"

"Dad, we agreed not to have awkward conversations, but you started it first."

Lao Lin was stunned: "Your father was seriously thinking about what kind of beautiful language to use to lead you into the wonderful world of mathematics. How could you hurt your father's heart like this?"

"I read the book 'Calculus' you asked me to borrow." Lin Zhaoxi took away the notebook, revealing the textbook underneath. "There are many beautiful insights in it."

"That wasn't written by me." Old Lin blushed.

"But the handwriting is yours?" Lin Zhaoxi turned the title page, "If we must say that modern human civilization is built on a definition, then its name must be - limit.

she recited.

"That's all due to our youth and ignorance." Lao Lin coughed.

“I think it’s beautiful.”

"Yes." Lao Lin slowed down his movements of picking bean sprouts. "But as time goes by, it's not enough to just think that mathematics is beautiful. It's not that it's not beautiful anymore. It's still something that people look forward to. But the hard work every day will gradually wear away your love and passion."

Lao Lin's words were very leisurely, and coupled with the movements of him picking bean sprouts, it seemed even more like a casual chat.

But Lin Chaoxi suddenly fell silent. Old Lin specifically told her all this.

He was so smart that he could definitely sense the difficulty she was having in learning these things. Lin Chaoxi didn't know how to describe this difficulty. It never came from the mountains, but from the distance between the climber and the top of the mountain.

"Calculus" is a required course for freshmen in the Department of Mathematics, including many comprehensive science subjects. Everyone knows that it is the foundation and that it should be quite difficult. However, after opening the book, they find that it is a little more difficult than they imagined.

The definition of the limit of light is long and difficult, with a mixture of various symbols, "assuming", "if...exists...so that", and "as long as...and". Compared with the knowledge of light before high school, the length of the definition of light is completely different.

Although Lao Lin had prepared courses on mathematical thinking and mathematical language in advance, which to a great extent alleviated her unfamiliarity with these definitional languages, advanced mathematics was still a very unfamiliar field.

But when she finished reading the book and the notes carefully and thought she understood the extreme definition, she took out a pen and paper and prepared to prove it again according to the notes, but her mind suddenly went blank.

She almost forgot what she had just learned.

When she truly understood the extreme definition, mastered the proof method, and turned to the next page, she suddenly realized that her understanding of the definition might not be deep enough.

She continued to learn little by little, and the repeated cycles of "thinking she had mastered it" and "actually not" even made her panic. After all, calculus was only the foundation of college mathematics.

"Dad..." Lin Zhaoxi said slowly, "Why is calculus so difficult? When you were learning it, didn't you think it was that difficult?"

"Is there a sentence in the book?" asked Lao Lin.

"Which one?"

"He used his almost godlike thinking to first explain the movement and images of the planets, the orbits of comets and the tides of the ocean," Lao Lin emphasized. "I didn't write this."

Lin Chaoxi turned to that page and found that it was written on the exercises of the first chapter with a ballpoint pen, and the handwriting was definitely not Lao Lin's.

"Um?"

"This is Newton's epitaph," Lao Lin asked. "Do you know why this sentence is written on it?"

"have no idea."

"Because some people also find it difficult." Lao Lin said, "Students from Sanwei University."

Lin Chaoxi nodded slowly.

"Do you know how high the IQs of Newton and Leibniz are?" Lao Lin asked her again.

"have no idea."

"Then Archimedes, Fermat, Descartes, Roberval, Desargues, Barrow, Varis, Kepler, Cavalieri..." Old Lin spat out world-famous names one by one. He spoke faster and faster, and there were even some names that Lin Chaoxi had never heard of.

“What are these people’s IQs?”

"I don't know either." Lin Chaoxi sat up straight and answered seriously.

"We don't know." Lao Lin was also very serious, "But what we know is that from the 7th century BC to the 17th century AD, all those great names came one after another, constantly raising questions, thinking about problems and solving problems, so that the man with 'almost god-like thinking power' finally established this discipline in the 17th century." Lao Lin paused, "And he is only one of the founders recognized by history.

"But all this was just the beginning of calculus being called a 'subject'. In the hundreds of years that followed, mathematicians continued to perfect it." Lao Lin stopped what she was doing and looked at him with a soft gaze, which made Lin Chaoxi feel that he was going to touch her head, but in the end he didn't.

He just said: "It is almost no exaggeration to say that it has given you airplanes above your head and railroad tracks under your feet, and that the world has finally become what it is today. Now you can slowly learn about it and understand it. It is such a fortunate process. Isn't 'difficult' the most natural thing?"

Lao Lin’s words made sense, and then he continued to pick bean sprouts.

And for a long time after that, Lin Chaoxi didn't say a word, and there was only the slightest "click" and "click" sounds in the air.

She opened the calculus book again, and she thought that the biggest difference between her and Lao Lin in mathematics might not be talent, but Lao Lin's attitude towards mathematics, which was much more sincere and humble than hers.

After that, she began to calm down and read books and do exercises. She was no longer distressed by difficulties, nor troubled by ignorance. Lao Lin just did her housework.

They sat in the small kitchen, eating a simple New Year's Eve dinner. Lao Lin told her something from time to time and teased her with various words.

However, here, it was the same as usual, with no festive atmosphere at all.

Only after eight o'clock did Lao Lin's phone keep ringing.

His students called one after another to wish him a happy new year. During the busiest time, as soon as one hung up the phone, the next one rang.

There were Huajuan, Lu Zhihao, An Beibei, Yao Xiaotian, Chen Chengcheng, and even Zhang Liang called. Although they didn't talk much, Fan Guzai still said "Happy New Year" very seriously.

In this atmosphere, Pei Zhi's phone calls also became very unusual.

Old Lin didn't talk much to anyone, including Pei Zhi. Lin Chaoxi chatted with him for a few words and hung up the phone naturally.

Crucian carp and tofu soup was warming on the gas stove. It was already very late. Firecrackers kept exploding outside the window, and laughter and joy could be heard from every household.

The clock struck midnight, along with the sound of firecrackers.

Lao Lin brought two cups of dark red liquid in transparent glass cups, which looked very real.

Lin Chaoxi discovered that there seemed to be no bubbles in the cup that Old Lin handed her.

"Coca-Cola or wine?"

“Coca-Cola.”

Lin Chaoxi didn't believe it.

They raised their glasses and clinked them lightly.

"Happy New Year!"

"Have fun together."

Lin Chaoxi took a sip carefully... and almost spit it out. It really was Coca-Cola.

"Minors are not allowed to drink." Old Lin said righteously, "Pei Zhi is to blame. I forgot to put the cap on the bottle when I answered his call yesterday. But it would be a waste if I couldn't finish it."

Lin Zhaoxi: “…”