We start with the customer and work backwards. And, very importantly, we are willing to be misunderstood for long periods of time.

Quotes from many sources. A particularly good source of quotes on this theme is: The Experts Speak: The Definitive Compendium of Authoritative Misinformation by Christopher Cerf and Victor Navasky (Pantheon Books, 1984).
This started out as a list of negative and pessimistic comments about new ideas, but, to provide some balance, I've begun to add a few overly enthusiastic and optimistic comments.

What's your favourite quote about programming?

People at the top don’t work harder than you. They work MUCH MUCH harder.
—Malcolm Gladwell

For whatever we do, even whatever we do not do prevents us from doing its opposite. Acts demolish their alternatives, that is the paradox.

I do not know they key to success, but the key to failure is trying to please everybody.
—Bill Cosby

The wailing and gnashing of teeth that you hear among Republicans is 68 percent envy and 32 percent sour grapes. Here is an idealistic, articulate young president who is enormously popular everywhere in the world except in the states of the Confederacy, and here sit the 28 percent of the American people who still thought Mr. Bush was doing a heckuva job at the end, gnashing their teeth, hoping and praying for something horrible to happen such as an infestation of locusts or the disappearance of the sun, something to make the president look bad, which is not a good place for a political party to be, hoping for the country to slide into chaos. When you bet against America, you are choosing long odds.

For whatever we do, even whatever we do not do prevents us from doing its opposite. Acts demolish their alternatives, that is the paradox.

"If you die after selling between 250 million and 700 million records you’ll be on the front page of every newspaper while the entire world mourns.
If you die after saving between 250 million and 700 million people from starvation, your death notice will be somewhere near the classifieds section."