Some of your classmates... well, let's just say they're unlikely to make the shelf. Shelf,...

Horace Slughorn:
Some of your classmates... well, let's just say they're unlikely to make the shelf.
Harry Potter:
Shelf, sir?
[Slughorn points to a wall of portraits of past "Slug Club" members]

Horace Slughorn:
Anyone who aspires to be anyone ends up here. But then again, you already are someone, aren't you, Harry?
Harry Potter:
Did Voldemort ever make the shelf, sir?
[Slughorn freezes]

Harry Potter:
You knew him, didn't you, sir? Tom Riddle? You were his teacher.
Horace Slughorn:
Mr. Riddle had a number of teachers whilst he was here at Hogwarts.
Harry Potter:
What was he like?
[no response]

Harry Potter:
I'm sorry, sir. Forgive me. He killed my parents.
Horace Slughorn:
I... of course, it's only natural you should want to know more. But I'm afraid I must disappoint you, Harry. When I first met young Mr. Riddle, he was a quiet, albeit brilliant boy committed to becoming a first-rate wizard. Not unlike others I've known. Not unlike yourself, in fact. If the monster existed, it was buried deep within.

How do you do, Tom? Don't. - You're the doctor, aren't you? - No. I am a professor. I don't believe you. She wants me looked at. They think I'm different. Well, perhaps they're right. I'm not mad. Hogwarts is not a place for mad people. Hogwarts is a school. A school of magic. You can do things, can't you, Tom? Things other children can't. I can make things move without touching them. I can make animals do what I want without training them. I can make bad things happen to people who are mean to me. I can make them hurt... ...if I want. Who are you? Well, I'm like you, Tom. I'm different. Prove it. I think there's something in your wardrobe trying to get out, Tom. Thievery is not tolerated at Hogwarts, Tom. At Hogwarts, you'll be taught not only how to use magic, but how to control it. You understand me? I can speak to snakes too. They find me. Whisper things. Is that normal for someone like me?