I am not worried, Harry,"said Dumbledore, his voice a little... - J.K. Rowling, Harry Potter and the Half-Blood Prince

"Snape raised his wand and pointed it directly at Dumbledore."Avada Kedavra!"

"Don't count your owls before they are delivered."

"It was, he thought, the difference between being dragged into the arena to face a battle to the death and walking into the arena with your head held high. Some people, perhaps, would say that there was little to choose between the two ways, but Dumbledore knew - and so do I, thought Harry, with a rush of fierce pride, and so did my parents - that there was all the difference in the world."

"I don't think you should be an Auror, Harry,"said Luna unexpectedly. Everybody looked at her. "The Aurors are part of the Rotfang Conspiracy, I thought everyone knew that. They're working to bring down the Ministry of Magic from within using a mixture of dark magic and gum disease."

"Killing is not so easy as the innocent believe."