Yu Tang was lying on the bed and was closing his eyes when he suddenly heard a knock on the door.

He thought it was Yang Xiaoyun who came to decoct the medicine for him, so he opened the door without thinking too much.

Outside the door, stood two men, one tall and one short, in black suits and wearing sunglasses.

"Hello, are you Yu Tang?" The short man stepped out with one foot while asking Yu Tang a question, jamming the bamboo door.

"I am. Who are you? Yu Tang saw these two people menacing, and his feet subconsciously moved back.

"Don't be nervous, we're from the NSA and don't have any ill will towards you. I just need your cooperation, come with us, there is someone who wants to see you. The tall man saw that Yu Tang was retreating, worried that he would make some radical moves, which would cause misunderstanding between the two sides, so he immediately revealed his identity and purpose to him.

When Yu Tang heard this, he stopped. After failing to call for the key of Yue Shi again in his heart, his combat power immediately fell to the point where he was only slightly stronger than Liu Ye, so he quickly examined the situation, and at the moment, the most important thing was to ask the reason and purpose of these two people who claimed to be from the National Security Agency to come to him.

"You say someone wants to see me, who is it?" Yu Tang asked.

"We don't know, but Dean Yang Xiaosheng should know, and then we will be responsible for bringing you and his safety and taking you to the place he designated." The short man replied.

At this moment, Yang Xiaosheng's voice came from behind the two.

"Yu Tang, it's okay, believe me, they're just bodyguards sent to us by the National Security Agency."

When Yu Tang heard Yang Xiaosheng's voice, he immediately relaxed. In the first branch of Chronos, he has already developed trust in Yang Xiaosheng.

Although this is another timeline, this Yang Xiaosheng is not Yang Xiaosheng, but Yu Tang has read it in the knowledge base of the key to the time before, as long as it is a branch line and the time is similar, the growth trajectory of everyone in it is basically the same.

If you compare the main timeline to the trunk of a tree, the branch is like a branch that suddenly extends from the trunk at some point. These branches may grow longer and longer over time, or they may stagnate, but they are all detached from the trunk. Therefore, before they become independent, the events and personality changes of any character in the branch are completely consistent with the main line. Based on this, the ancients divided the timeline into different levels according to different branch states. And they suspect that the main line of time, there is more than one.

But until the day of civilization's decay, no scientist claimed to have discovered a second timeline. Their time travel is limited to branching.

So, who came up with the concept of the main line of time? The vague expression "it" is also used in the key to time.

It's as if from the moment all people are born, they have been instilled with this concept in their minds by this guy who doesn't know whether man is a god or not. After the development of science and technology to a certain extent, everyone tacitly believes that what they are in is the main line of time.

The so-called change of the past claimed by the first generation of time travelers was nothing more than that they changed the development path of a certain branch.

Yu Tang learned from ancient records that "it" was called "Du Yin" in ancient mythology, and in modern expressions, it was "the creator god".

As for why the main timeline branched, what were the conditions for the establishment of the branch, and whether anyone could change the development of the main timeline, these questions were ultimately boiled down to cause and effect in the knowledge base of the key to time.

Thus, this series of studies becomes a Möbius ring—the study of cause and effect and the mysteries of the timeline, like this circle that is always faceted, forming a cycle that is extremely frightening to some but infinitely desirable to others.

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"Okay, I'll go with you." Yu Tang relaxed his body and sat back on the edge of the bed. As he sat down, the sharp pain from the wound that had not yet healed hit him again, and he gasped.

At this time, Yang Xiaoyun's voice came from outside, "Dad, why are you taking him away?" He'll have to heal for a few more days. ”

Yang Xiaosheng turned around, and he didn't know what to say to her, so Yang Xiaoyun's tone became helpless, "Okay, then you have to come back early, I'll give him today's medicine, and he can drink it again when he comes back in the evening." After saying this, she walked into the hut with the firewood.

And Yu Tang was carried behind him by a tall man. The group of four immediately set off and hurried to the mysterious cave non-stop.

A few hours later, Yang Xiaosheng and Yu Tang arrived at the entrance of the cave, escorted by two staff members of the National Security Bureau.

Yu Tang looked around and found that except for a simple fence wall at the entrance of the cave, it was no different from the environment he remembered. After Yang Xiaosheng stepped forward and opened the fence, the four of them entered the hole.

At this time, Yang Xiaosheng's mobile phone rang. He took out his mobile phone and connected to the call, listened to a few words and hung up.

"He said let's just wait at the entrance of the cave, and only Yu Tang was left in the cave." Yang Xiaosheng said the prophet's instructions, and then he turned his head and said to Yu Tang, "That person said you know how to do it. After seeing Yu Tang nodding, the tall man put him down, and the three of them immediately exited the cave.

In fact, along the way, seeing the familiar road, Yu Tang had already guessed who was going to see him. However, the bitter lesson of the previous timeline taught him that more is better than less, and both the Prophet and Yang Xiaosheng's father had instructed him to be cautious in his words and deeds.

Therefore, he did not ask Yang Xiaosheng questions, but kept his silence while his brain was running at high speed.

At this moment, Yu Tang walked towards the depths of the cave, and found the stone hidden in the inner wall of the cave with his memory, and soon after pressing it gently, there was a slight vibration from the stone wall, and it slowly opened to him. And this time, sitting on that stone chair was no longer a projection of the prophet, but a real person!