“One should cultivate good habits of memory, for it is capable of making existence a Paradise or an Inferno.”

“Never compete with someone who has nothing to lose.”

“Friendship multiplies the good of life and divides the evil.”

“True friendship multiplies the good in life and divides its evils. Strive to have friends, for life without friends is like life on a desert island... To find one real friend in a lifetime is a goo...”

“Though such authority and respect shouldn't be handed to all and sundry, have in caution's innermost room a confidant, a faithful mirror, whose correction you value when disillusionment is necessary.”

“Cunning grows in deceit at seeing itself discovered, and tries to deceive with truth itself.”

“The truths that matter most to us come always half spoken.”

“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.”