“Doing worse with more knowledge means you are doing something very wrong.”

“Your strength as a rationalist is your ability to be more confused by fiction than by reality. If you are equally good at explaining any outcome, you have zero knowledge.”

“You couldn't changed history. But you could get it right to start with. Do something differently the FIRST time around.This whole business with seeking Slytherin's secrets... seemed an awful lot like the sort of thing where, years later, you would look back and say, 'And THAT was where it all started to go wrong.'And he would wish desperately for the ability to fall back through time and make a different choice. Wish granted. Now what?”

“Do not think that fairness to all sides means balancing yourself evenly between positions; truth is not handed out in equal portions before the start of a debate.”

“Not every change is an improvement but every improvement is a change; you can't do anything BETTER unless you can manage to do it DIFFERENTLY, you've got to let yourself do better than other people!”

“Trying and getting hurt can't possibly be worse for you than being... stuck.”

“- With respect, Professor McGonagall, I'm not quite sure you understand what I'm trying to do here.- With respect, Mr. Potter, I'm quite sure I don't. Unless - this is a guess, mind - you're trying to take over the world?- No! I mean yes - well, NO!- I think i should perhaps be alarmed that you have trouble answering the question.”