Harry Potter and the Deathly Hallows (Harry Potter, #7)

by J.K. Rowling

“If you wish to leave with your students, we shall not stop you. But if any of you attempt to sabotage our resistance or take up arms against us within this castle, then, Horace, we duel to kill.”

“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?”