“I think therefore I am. ”

“It is not enough to have a good mind the main thing is to use it well. ”

“The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.”

“The reading of all good books is like a conversation with the finest minds of past centuries.”

“I am indeed amazed when I consider how weak my mind is and how prone to error.”

“When it is not in our power to follow what is true, we ought to follow what is most probable.”

“I am all in a sea of wonders. I doubt; I fear; I think strange things, which I dare not confess to my own soul.”

“If you take too long in deciding what to do with your life, you'll find you've done it.”

“Fear and doubt are major stampeders.”

“The truth." Dumbledore sighed. "It is a beautiful and terrible thing, and should therefore be treated with great caution.”

“The truth is rarely pure and never simple.”

“Never tell the truth to people who are not worthy of it.”