Once upon a time, the world's rulers realised that they needed to work to avoid war at all costs. Once, rich people understood that it was good to help poor people everywhere. Once, there were drugs to fight almost every infectious disease. Once, there was ice at both the North and South Pole. Once, people from poor countries weren't so desperate that they crossed dangerous seas to escape. Once, you could walk down busy city streets without fear of terrorist attack.
Don't believe me? Well, it was only a story.