"[The sorting hat] only put me in Gryffindor," said Harry in a defeated voice, "because I asked not to go in Slytherin…"
"Exactly," said Dumbledore, beaming once more. "Which makes you very different from Tom Riddle. It is our choices, Harry, that show what we truly are, far more than our abilities."
Dumbledore in Harry Potter and the Chamber of Secrets (2002).
