"Insanity: Doing the same thing over and over again and expecting different results."
— Albert Einstein

"The statistics on sanity are that one out of every four people is suffering from a mental illness. Look at your 3 best friends. If they're ok, then it's you."
— Rita Mae Brown

"There's a fine line between genius and insanity. I have erased this line."
— Oscar Levant

"The reason I talk to myself is because I’m the only one whose answers I accept."
— George Carlin

"It is sometimes an appropriate response to reality to go insane."
— Philip K. Dick

"I became insane, with long intervals of horrible sanity."
— Edgar Allan Poe

"The definition of insanity is doing the same thing over and over and expecting different results."
— Benjamin Franklin

"Dispute not with her: she is lunatic."
— William Shakespeare (The Tragedy of King Richard III)

"Insanity is catching."
— Terry Pratchett (Making Money)

"We do not have to visit a madhouse to find disordered minds; our planet is the mental institution of the universe."
— Johann Wolfgang von Goethe

"When you get to the end of your rope. Tie a knot and hang on."
— Franklin D. Roosevelt

"Men have called me mad; but the question is not yet settled, whether madness is or is not the loftiest intelligence– whether much that is glorious– whether all that is profound– does not spring from disease of thought– from moods of mind exalted at the expense of the general intellect."
— Edgar Allan Poe (Complete Tales and Poems)

"Do you think it's possible for an entire nation to be insane?"
— Terry Pratchett (Monstrous Regiment)

"First sign of madness, talking to your own head."
— J.K. Rowling

"Mad hatter: how is a raven like a writing desk?
*squabble*
Alice: so how IS a raven like a writing desk?
Mad Hatter: I haven't the slightest idea."
— Lewis Carroll (Alice in Wonderland)

"Now this is the point. You fancy me a mad. Madmen know nothing. But you should have seen me. You should have seen how wisely I proceeded..."
— Edgar Allan Poe (The Tell-Tale Heart)

"I attributed the incidence to temporary insanity, and in my own defense, I'd like to say I haven't run over anyone since."
— Janet Evanovich (One for the Money)

"Yet mad I am not...and very surely do I not dream."
— Edgar Allan Poe (The Black Cat)

"People can do great things. However, there are some things they just CAN'T do. I, for instance, have not been able to transform myself into a Posicle, despite years of effort."
— Brandon Sanderson (Alcatraz Versus the Evil Librarians)

"Sweet, crazy conversations full of half sentences, daydreams and misunderstandings more thrilling than understanding could ever be."
— Toni Morrison (Beloved)

"Dreaming permits each and every one of us to be quietly and safely insane every night of our lives."
— William Dement

"Crazy people made him crazy. It was as if he personally resented them giving into madness - in part, because he so frequently labored to behave sanely. When some people gave up the labor of sanity, or failed at it, Garp suspected them of not trying hard enough. "
— John Irving (The World According to Garp)

"The only difference between Salvador Dali and a crazy man is that Salvador Dali is not crazy!"
— Salvador Dali

"There are certain people in whom you can detect the seeds of madness - seeds that have remained dormant only because the people in question have lived relatively comfortable, middle class lives. They function perfectly well in the world, but you can imagine, given a nasty parent, or a prolonged bout of unemployment, how their potential for craziness might have been realized."
— Zoë Heller (What Was She Thinking?: Notes on a Scandal: A Novel)

"I lie on the floor, washed by nothing and hanging on. I cry at night. I am afraid of hearing voices, or a voice. I have come to the edge, of the land. I could get pushed over."
— Margaret Atwood (Cat's Eye)

""I have no artistic talent, I'm just visually insane""
— Emma Barry

"I am sitting with a philosopher in the garden; he says again and again 'I know that that’s a tree', pointing to a tree that is near us. Someone else arrives and hears this, and I tell him: 'This fellow isn’t insane. We are only doing philosophy.'"
— Ludwig Wittgenstein (On Certainty)

"To be mad is to feel with excruciating intensity the sadness and joy of a time which has not arrived or has already been. And to protect their delicate vision of that other time, madmen will justify their condition with touching loyalty, and surround it with a thousand distractive schemes. These schemes, in turn, drive them deeper and deeper into the darkness and light (which is their mortification and their reward), and confront them with a choice. They may either slacken and fall back, accepting the relief of a rational view and the approval of others, or they may push on, and, by falling, arise. When and if by their unforgivable stubbornness they finally burst through to worlds upon worlds of motionless light, they are no longer called afflicted or insane. They are called saints."
— Mark Helprin (Winter's Tale)

"Insanity is nothing more than normality, and normality, is surely insanity. "
— Aruna S.

"Sane people did what their neighbors did, so that if any lunatics were at large, one might know and avoid them."
— George Eliot

"Don’t you know what god is? God is everything and God is nothing; for the perfection created by man cannot be anything other than nothing. They decided to give a name to nothingness, and thereby the made it become something. Like you… God, who is nothing, can no longer be nothing since he is God. You could be a god for men. They need to give a body to nothingness so that nothingness can be seen and touched-at least with the imagination."
— Aldo Palazzeschi (Man of Smoke)

"Fat realized that one of two possibilities existed and only two; either Dr. Stone was totally insane – not just insane but totally so – or else in an artful, professional fashion he had gotten Fat to talk; he had drawn Fat out and now knew that Fat was totally insane."
— Philip K. Dick (VALIS)

"and for every statement I make to you pointing out that or any view point, I can give you twenty two more all in conflict with one another. They all belong to me and none of them belongs to me."
— The troops for Trudie Chase