"Today's lesson will uncover a truly thrilling piece of history."
Professor Binns said in his usual lifeless tone.
"The Goblin Rebellion of 1752, and the brilliance and tragedies that emerged during it. More specifically, we will examine the devastating impact this event had on the Wizarding World's milling industry..."
"What are you looking at?" Severus asked.
"My notes from when I was a student," Pomona said listlessly. Heaven knew how someone who loved sleeping so much had managed to stay awake in Professor Binns's class.
He leaned over with interest and glanced at them.
"So colorful," he said, as though in disdain.
Pomona, meanwhile, recalled his Potions textbook, covered in black-ink revisions until it was utterly unrecognizable.
How was she supposed to strike back?
"Did you know that eleven days vanished from September 1752?" Severus suddenly said.
"What?"
"No one was born or died during those eleven days. No one made bets or signed trade agreements. It was as if they went to sleep on the night of September 2 and woke up on September 14," Severus said.
"I remember. It seemed to be because they changed calendars, from the Julian calendar to the Gregorian Calendar," Pomona said.
"Is that so?" he said with a smile.
"What else could it have been?" Pomona asked.
"Like the Quidditch World Cup of 1877. Every ticket had been sold, yet neither the fans nor the players remembered the match. Only Britain's Beater had lost half his teeth, Canada's Seeker had his knees turned backward, and half the Argentina team had been tied up in a British underground pub," Severus said.
Pomona was left speechless, because many people had tried to explain such mass amnesia.
In New York, Newt Scamander had used Doxy venom and rain summoned by a Thunderbird to erase the memories