People who are crazy enough to think they can change the world, are the ones who do.

Source: "Think Different" advertising campaign for Apple Inc. (1997) Additional Information: This quote from Apple's "The Crazy Ones" advertisement, part of the firm's 1997  "Think Different" campaign, is usually attributed to Steve Jobs; however, it was actually written by Rob Siltanen, the creative director and managing partner at TBWA/Chiat/Day, the company Apple hired to create this advertising campaign. While Steve Jobs did have executive input when it came to the content of the ad, Siltanen is the person who actually composed this text from "The Crazy Ones," with the participation of Lee Clow, TBWA/Chiat/Day CEO and Chief Creative Officer. Here is the full version of "The Crazy Ones":

Here’s to the crazy ones. The misfits. The rebels. The troublemakers. The round pegs in the square holes. The ones who see things differently. They’re not fond of rules. And they have no respect for the status quo. You can quote them, disagree with them, glorify or vilify them. But the only thing you can’t do is ignore them. Because they change things. They push the human race forward. And while some may see them as the crazy ones, we see genius. Because the people who are crazy enough to think they can change the world, are the ones who do.

The influential 1997 ad, used in a TV commercial and print advertisements, helped revive Apple's image at a time when the company was struggling.