How we cite our quotes: All quotations are from Harry Potter and the Half-Blood Prince.
Quote #7
HARRY: I'm going to tell you something. Something others have only guessed at. It's true. I am the Chosen One. Only I can destroy him, but in order to do so, I need to know what Tom Riddle asked you all those years ago in your office, and I need to know what you told him.
Okay. Here, Harry is actually being honest with Slughorn (to get what he wants, of course). Normally Harry doesn't make it a habit to go around advertising that he's the Chosen One, but since he knows it'll get Sluggy chatting, he lets the cat out of the bag.
Quote #8
SLUGHORN: Please, don't think badly of me when you see it. You've no idea what he was like, even then.
This is it: Slughorn is finally going to tell the truth about what happened with Voldemort all those years ago. We're not sure if he's really telling the truth about not knowing Voldemort's true nature, but we'll let that go, since he's at least giving Harry the real memory. And with all the deceit and lying going on, we really needed a moment of truth. Phew.