The city of the sun is a magical place that some people talked about a very long time ago. It's kind of like a super special city where everything is perfect and wonderful.
In this city, everyone works together to make sure that everything is fair and everyone has what they need. There are no rich or poor people. Everyone shares everything equally. They also work very hard to make the city clean and beautiful.
The people who lived in the city were very wise and believed that people should be kind to each other and respect each other's differences. They didn't fight or argue because they thought it was better to work together and solve problems peacefully.
Even though the city of the sun wasn't a real place, some people think that it's important to think about it and try to make the world a better place by being kind and working together.