Contemplations On Insanity

I think everyone asks themselves if they are insane from time to time. I feel like the frequency of this idea has gone up for me lately, so I thought I'd get some expert opinions on the subject:

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

Insanity: doing the same thing over and over again and expecting different results.
Albert Einstein

Love: a temporary insanity, curable by marriage.
Ambrose Bierce

When we remember that we are all mad, the mysteries disappear and life stands explained.
Mark Twain

The sanity of society is a balance of a thousand insanities.
Ralph Waldo Emerson

Insanity in individuals is something rare -- but in groups, parties, nations, and epochs it is the rule.
Friedrich Nietzsche

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

In all matters of opinion, our adversaries are insane.
Oscar Wilde

Insanity is hereditary; you can get it from your children.
Sam Levenson