“I'm a pessimist because of intelligence, but an optimist because of will.”

“I guess I'm a hopeful optimist, because to be a pessimist is to be suicidal.”

“Are you an optimist or a pessimist?" "I can't remember. Which?" "Do you know what those words mean?" "Not really." "An optimist is positive and hopeful. A pessimist is negative and cynical." "I'm an optimist." "Well, that's good, because there’s no irrefutable evidence. There’s nothing that could convince someone who doesn’t want to be convinced. But there is an abundance of clues that would give the wanting believer something to hold on to.”

“The difference between an optimist and a pessimist? An optimist laughs to forget but a pessimist forgets to laugh.”

“Both optimists and pessimists contribute to society. The optimist invents the aeroplane, the pessimist the parachute.”

“The the question whether I am a pessimist or an optimist, I answer that my knowledge is pessimistic, but my willing and hope are optimistic.”