Harry Potter and the Deathly Hallows
"…Goblin notions of ownership, payment, and repayment are not the same as human ones. […] We are talking about a different kind of being," said Bill. "Dealings between wizards and goblins have been fraught for centuries. […] To a goblin, the rightful and true master of any object is the maker, not the purchaser. All goblin-made objects are, in goblin eyes, rightfully theirs." (25.93)
"Karkaroff intends to flee if the Mark burns."
"Does he?" said Dumbledore softly… "And are you tempted to join him?"
"No," said Snape. […] "I am not such a coward."
"No," agreed Dumbledore. "You are a braver man by far than Igor Karkaroff. You know, I sometimes think we Sort too soon…" (33.144)
"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?" (35.96-98)