Ten o'clock on Tuesday night.

　　 Harry and Ron met in the Gryffindor common room at night.

　　 They all looked very tired. At noon today, Professor McGonagall drove them into the school by flying the car and punished them for the injury.

　　 Ron was fined to Filch and helped him wipe all the trophies in the trophy showroom, and was not allowed to use magic.

　　 And Harry was sent to the public toilet in the castle to clean the corridor. They have been busy from three o'clock in the afternoon until now. There is no one else in the common room. They are the last two to come back.

　　 Harry and Ron did not go back to the dormitory first, but lay down on the couch in the lounge near the fireplace.

"I feel that my hand is about to be broken. Filch, that old thing must be deliberate. He stared at me all the time. He only gave me one minute to go to the toilet. Even if I solve it on the spot, It's not enough." Ron grumbled to Harry while rubbing his sore and numb arms.

　　 "You're just tired of your arms." Harry said weakly, "I cleaned at least eight public bathrooms today. God knows how many times I vomited? Even I still feel a smelly smell on my body."

　　 "Ah, then don't lean so close to me, the smell is spreading to me."

　　 "Anyway, I have to take a bath after a while. If I get it, I get it."

　　 They made a fuss for a while, and soon they talked about "business".

　　 "Why haven't you seen Hermione these days?"

"Yes, since the last incident at Quidditch Stadium, she seems to have rarely appeared in the Gryffindor lounge. Even if we saw her, she hurriedly said hello to us. It looks like he's busy with something."

　　 "Very mysterious."

　　 "She must be hiding something from us."

　　 The two of them looked at each other, and they saw the same thoughts as they were in each other's eyes.

　　 "We can investigate her secretly."

"I think so."

　　 Harry and Ron smiled at each other, raised their fists, and when they were about to touch each other, the whole castle suddenly shook!

　　 "Boom!"

　　 A huge explosion sounded like a thunder before the rainy night in a quiet summer, awakening countless little wizards who had just entered their dreamland!

　　......

　　Tuesday at four o'clock in the afternoon.

　　 In Dumbledore’s principal’s room, Lynn sat opposite the desk as usual, watching Old Deng take out a golden luminous timer from the drawer.

　　 "It is not difficult to apply for this thing, but as long as you apply for it, you have to sign it along with the letter of commitment."

　　 Insert a sentence, really good, it is worth installing, after all, you can cache books and read them offline!

　　 Dumbledore gave Lynn a piece of parchment, asking Lynn to promise not to use the time converter for things unrelated to learning. If there is a violation, he will bear the consequences of the accident.

　　 This undertaking is not a contract with magical effect, but just a written agreement with legal effect. This form of agreement means that even if the person who signed the undertaking violates this undertaking, as long as it is not discovered by anyone, then he is not in breach of the contract.

　　 Lynn did not hesitate and signed his name directly on it.

　　 After he bookmarked the promise, Dumbledore did not directly give him the time converter, but said in a deep voice.

　　 "You know that you can use this thing to go back in time, but why has no one ever thought of using it to change past history?"

　　 Lynn scratched his eyebrows, and said in deep thought, "I seem to have seen it in a book. The time converter can only be used to understand history, and cannot change the historical trajectory that has occurred."

　　 "You are only half right. The time converter really cannot change the history that has occurred, but it can change the history that has not yet occurred."

"What's the meaning?"

"The current time converter has basically become a learning tool for Hogwarts. Excellent, but the little wizard who doesn’t have enough time can apply to the professor to obtain it, and the professor will consider the quality of the little wizard. If He is calm, wise, and pays attention to the rules, then he meets the conditions for using the time converter.

After the little wizard gets the time converter, the main purpose is to use it to take time conflict classes. For example, today’s two elective courses-Muggle Studies and Protecting Fantastic Animals, have conflicting class times. Then the little wizard who has got the time converter can turn the time converter after finishing the Muggle research class, and go back to the beginning of this class to take the class of protecting magical animals.

There are two time points in this. The first one is this time after the Muggle Studies class. This little wizard with a time converter has taken the Muggle Studies class. This has become a history. He uses After the time converter has returned to the past, he can no longer change this established fact.

　　 The second point in time was when the little wizard used the time converter to go back to the past, and then finished the magical animal protection lesson. This time is actually the same as the time he used the converter. But at this time, he changed a history that hadn't happened yet, and he took two different classes at the same time by himself. "

　　 Lynn frowned, he didn't understand what Dumbledore was saying.

　　 "About the second point in time, he took two different courses by himself~lightnovelpub.net~ This has happened after the course started. How can what has happened be called history that hasn't happened yet?"

Dumbledore shook his head: "It has indeed happened, but when these two classes are in class, does anyone know that there is now a person who is taking two different classes at the same time? The children in the Muggle studies class I only saw this little wizard come to the Muggle study class. The children who took the magical animal protection class only saw him come to the magical animal protection class. In the memory of all those who saw this little wizard, he just took one. class."

　　 Lynn made a rebuttal.

"Then if the little wizards who have taken these two classes meet after class and tell each other that the little wizard has taken the class they are taking, no one will know that he has taken two different classes at the same time. Is history?"

　　 Dumbledore smiled and looked at Lynn with profound eyes: "Pay attention to the time you said, Lynn."

　　 Lynn was startled.

The point in time he said is already after the two classes. At this time, the little wizard has returned to the time he used the time converter, even though the little wizards in the two classes ventilate after class. Then they know that this matter also belongs to the future after the time converter is used.

　　 And the future means that it hasn't happened yet!

　　 "In other words, the history judged by the time converter does not represent objective history, but people's subjective history?" Lin En asked ponderingly

　　 "The moment you use the time converter, the objective history has been changed."