We think this world is a “vale of tears,” a “slough of despond” compared with what it could be — and will be in the future — if we do the right things. I’m not an optimist by temperament, but by evidence. That’s what changes my mind. We’re not saying, “Don’t worry, be happy.” We’re saying, “Don’t despair, be ambitious.”

From: Do Humankind’s Best Days Lie Ahead? The Munk Debates
By: Alain de Botton   Malcolm Gladwell   Matt Ridley   Steven Pinker