The corners of the hallway were concealed, and Tom could feel himself flying backward rapidly, turning everything around him into a mosaic of shapes and colors. The flight was so fast that his eardrums swelled.
Fortunately, the sensation lasted only a short while before Tom's feet touched solid ground and everything became clear again. Tom and Hermione stood in front of a portrait, next to which was the staircase leading to the North Tower.
Tom could feel the golden chains of the Time-Turner tightening around his neck, but he didn't have time to do anything else as he ran with Hermione up the narrow spiral staircase.
In the next second, they heard this conversation.
"-I think it's this way." Tom's voice came from outside.
Followed by Hermione's voice, "I don't think so, you see, you can see a bit of the lake from the window, so it's the south side of the castle... let's go to the North Tower."
Tom knew that in a few seconds, they would find that staircase.
It was an incredible sensation: being inside the stairs and outside them at the same time. A straight line made a turn, intersecting with the point where it used to be.
"Let's go!" Hermione's face turned slightly pale. "We can't let our past selves see us!"
Tom led Hermione toward the stairs.
The sound of their movements alerted the past Tom and Hermione, who followed them and found the staircase.
"My instinct tells me this is the staircase to the North Tower..." said the past Tom, standing at the entrance of the staircase. But although he had found the entrance, he didn't rush in. Instead, he took a moment to look at the portraits before entering.
By then, Tom had run to a small window in the tower, had transformed into a phoenix, jumped out of the window with Hermione, and landed softly on the ground.
"Arithmancy?" Tom looked at Hermione for advice as he removed the gold Time-Turner necklace from his neck.
Hermione rolled her eyes, ignored him, and walked through the middle of the castle, passed through the main door, and entered the vestibule. By this time, the vestibule was empty, and a golden sunbeam shone through the outer glass window onto the marble floor, where Hermione stood right in the center. The bright light cast a shadow over her face, making her features even more defined.
She still seemed reluctant to talk to Tom and appeared to be in a bad mood.
He stepped forward, and Tom followed.
"What can I do to calm you down?" Tom took Hermione's hand, and the two of them stopped in front of the hallway stairs.
Hermione turned her head to look at him.
Tom leaned closer and slipped the rolled-up black socks into the pocket of Hermione's robe. "I made a mistake in Divination class..."
A smile finally appeared on Hermione's face, her left hand gently resting on Tom's ear, then she leaned in and touched his lips like a dragonfly.
Tom's eyes widened, and he felt like everything was right again.
"Do you forgive me?"
Hermione's eyes widened, and she adorably shook her head. "It's just a reward for being a good boy who learns from his mistakes."
She turned around, ran like a bird twice, and turned back to Tom. "Next time, you'll have to wear it for me!"
And with that, she sat on the stairs, putting back on the black socks they had taken off.
"- You'll be late if you don't hurry." As Hermione changed her socks and put her shoes back on, a soft voice sounded above their heads.
It was Dumbledore again.
He stood on the first-floor stairs with a smile on his face, looking down.
The old bee! Tom cursed inwardly, dragging Hermione, who was already blushing, towards the Arithmancy classroom.
The teacher of this class was Professor Septima Vector.
Arithmancy is a magical discipline that studies the magical properties of numbers, including predicting the future with numbers and numerology. Those who practice this discipline are called "arithmancers."
It is different from traditional divination, which relies on interpreting vague images, such as crystal balls, tea leaves, or reading palm lines, or on interpreting the internal meaning of things from random figures or randomly written words. It is based on a set of rules and rigorous mathematical calculations. The magical world of Arithmancy is based on knowledge from Kabbalah and Pythagoras's philosophy. They reduced the sum of all letters in the alphabet to a numerical value from 1 to 9 and applied it to divination.
For Hermione, this subject that required rigorous logical thinking was very appealing.
"8:57." Tom took a moment to look at the time when he arrived outside the empty Arithmancy classroom. Thanks to Professor Trelawney, he hadn't delayed the class; instead, he had left much earlier.
If he had stayed until ten, Tom would have had trouble. Since the hourglass turns back one hour, Tom and Hermione had to be careful because instead of staying where they were, they would go back to where they were an hour ago.
This compels the time traveler to be very, very careful and cautious. They have to remember when they are in an isolated environment to avoid going back and finding themselves standing in the Great Hall, in plain view of the entire school—that would be their end.
But here's the good news: as long as it hasn't happened, it won't happen.
This may seem like a meaningless statement, but it's a very intuitive explanation of the problems that arise in time travel: the fact that what the time traveler observes cannot be changed.
In other words, what Tom and Hermione saw in the past must have happened. Tom and Hermione can alter what they don't see, but as long as they see it in the past, nothing can be changed.
For example, if in the past Tom and Hermione saw a reindeer fall on the shore of the Black Lake, then no matter how hard they try, there will be a reindeer that will fall on the shore of the Black Lake.
Because this is an unchangeable fact.
Although Tom and Hermione will save the world during the flashback, they couldn't do anything to change the fact that a reindeer had fallen by the lake.
And what's worse, the more details they have, the harder it will be to change that fact.
Let's take the reindeer example. If Tom wanted to save the reindeer, he could have transformed himself into a deer and fallen by the lake, thus recreating the scene he had seen before.
But if the previous Tom and Hermione had confirmed the reindeer's death, Tom would have had to find a deer carcass to place there and overcome it.
Toying in an unknown space is the key to traveling back in time.
Tom and Hermione pushed open the classroom door and entered. Before entering, Tom's gaze swept over a broom closet in the corner of the hallway, revealing a small smile.