“Tell me one last thing,” said Harry. “Is this real? Or has this been happening inside my head?”
Dumbledore beamed at him, and his voice sounded loud and strong in Harry’s ears even though the bright mist was descending again, obscuring his figure.
“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?”
Harry Potter and the Deathly Hallows – J.K. Rowling