"The liar's punishment ... is that he cannot believe anyone else."

"Common sense is instinct. Enough of it is genius."

"The chief objection of playing wind instruments is that it prolongs the life of the player."

"Lack of money is the root of all evil."

"This is the true joy in life -- being used for a purpose recognized by yourself as a mighty one..."

"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man."

"For every person who wants to teach there are approximately thirty people who don't want to learn--much."

"If you would thoroughly know anything, teach it to others."

"The true teacher defends his pupils against his own personal influence."

"Teachers open the door. You enter by yourself."

"Experience teaches only the teachable."

"I never teach my pupils. I only attempt to provide the conditions in which they can learn."