"Fat Fish?"

At the instant he saw this term.

Xu Yun's heart suddenly skipped a beat.

Although the term doesn't sound very pleasant, a bit silly even.

But across Xu Yun's social circle, there is only one person who would call him that.

And that is...

Isaac Newton, Little Niu.

But...

How did Little Niu's letter end up in his hands?

According to the previous hints from the Halo, wasn't the timeline within the dungeon supposed to be stagnant?

Thinking of this.

Xu Yun couldn't help but take a deep breath, braced himself, and continued reading.

"Mr. Feiyu, open personally:"

"Mr. Feiyu, it's been a full five years since you suddenly disappeared, Uncle William, aunt, and Lilani still miss you dearly."

"At that time, you left only a letter at the stall telling you met your family near the Grantham District, and then left without even paying for the meal."

"However, thanks to you, our tomato sauce sales have been excellent, and with the support of the district quickly occupied a large market."

"According to the original agreement, your living expenses were deducted, totaling Guinea... oh no, now it's called Pounds, sixty-seven in total..."

"Considering that this letter may not reach your hands smoothly, these gold coins are temporarily kept by me, with a storage fee of 0.0008 per day..."

Seeing this.

Xu Yun's eyelid twitched suddenly, and he slapped his forehead.

Good heavens.

You really are something, Mr. Niu, so I have to pay a storage fee to save my own money?

Moreover, a daily interest of 0.0008, even in 2022, could be considered usury.

At least learn from those kind-hearted readers who can defer updates without any interest.

But soon.

Xu Yun managed to calm his emotions.

He still hadn't figured out the method of letter dispatch, and nobody knew if he could receive those Pounds next time.

Plus, the sales of the current "One Insect Extinct" are quite good, Xu Yun is not as desperate for money.

Therefore, compared to those Pounds dividends, he actually cares more about other information left in his heart by Little Niu.

For example.....

The timeline of sending the letter.

According to the situation revealed in Little Niu's letter, the time of writing the letter should be five years after he disappeared.

This is clearly somewhat abnormal.

Because according to the previous hint from the Halo.

The timeline inside the 1665 dungeon should have been paused, continuing until his next return.

But now it seems...

Little Niu and the others seem to be able to 'move' again?

Thinking of this.

A new possibility suddenly emerged in Xu Yun's mind:

Could it be...

This is Little Niu in the simulated timeline?

This guess indeed explains the origin of the letter, but if so, what will his next entry into the 1665 dungeon be like?

If the two timelines influence each other, then the Halo undoubtedly is making a mockery of itself, this is a mistake the Halo should not make.

But if they are independent, what is the meaning of this letter?

Why did it appear at this point in time?

Even...

Could it have some unknown key link with Old Su burning money to mourn him?

"There's still too little information..."

Xu Yun gently shook his head, glanced at the letter in his hand again, and his gaze lingered a bit longer on Lilani's name.

Then he thought of something and his expression relaxed immediately:

"When I first met Lilani, she should have been only five or six years old, even if it's been five years, the girl is just around ten... at most twelve years old."

"Thankfully, thankfully, nothing's happened yet."

Lilani.

She was the mischievous kid in the 1665 dungeon who gave Xu Yun a lump of cow dung upon meeting, and during the simulation process, apart from Hook, the one who affected Xu Yun the most.

According to the Halo's simulation results.

This girl's personality turned increasingly introverted after he left, she dropped out at fifteen to work.

At nineteen, she went to the Netherlands to find him but unfortunately died in a shipwreck at sea.

Even calculating by the maximum age, Lilani is now only twelve at most, there are still a good few years until the tragedy at nineteen, still a lively little girl.

If Xu Yun can contact Little Niu, he completely has the chance to avoid the tragedy.

Thinking of this.

Xu Yun took up the letter again and continued reading.

Just as the letter stated: 𝗳𝗿𝐞𝕖𝘄𝗲𝕓𝗻𝚘𝚟𝕖𝐥.𝚌𝕠𝕞

"...After you left, the plague gradually dissipated, and the school reopened four years ago, I returned to the University of Cambridge."

"I am now the new Professor Lucas at Trinity College, Cambridge University, along with the dividends earned from tomato sauce, I've completely freed myself from that woman's control, achieving economic independence."

"Over the years, relying on the Han Li expansion and Yang Hui's Triangle model, I've built a new set of mathematical tools."

"And have made considerable achievements in theory, the specific formulas are as follows....."

Looking at the flamboyant handwriting on the envelope, Xu Yun could imagine roughly how Little Niu looked when writing these words.

Without accident.

This part should be Little Niu introducing his recent situation, the mathematical tools he mentioned are naturally calculus.

According to the Halo's previous simulations.

Little Niu deduced Han Li (Taylor) expansion's third-order formula in April 1666, laying a solid foundation for calculus.

The time of Little Niu writing the letter should be between 1671-1672, the calculus model must have been completely established.