樂觀者和悲觀者對社會都有貢獻。樂觀者發明飛機，悲觀者發明降落傘。Both optimists and pessimists contribute to our society. The optimist invents the airplane and the pessimist the parachute.

Both optimists and pessimists contribute to our society. The optimist invents the airplane and the pessimist the parachute. 樂觀者和悲觀者對社會都有貢獻。樂觀者發明飛機，悲觀者發明降落傘。 - GIL STERN