Ruan Ji was a person who lived long ago in China, kind of like a superhero from a long time ago. He was really good at writing poems and playing music, like a very talented musician. He was also known for being a rebel, which means he didn't always follow the rules and liked to do things his own way.
When Ruan Ji was alive, China was ruled by a big government that had strict rules about how people should behave. Ruan Ji didn't like these rules and thought that people should be free to express themselves in their own way. He wrote poems that talked about how people should be able to do what they want and not be judged by others.
But even though he was a rebel, Ruan Ji was really well-respected by the other people in China who liked him for his creativity and his bravery. He inspired lots of other people to be more creative and to stand up against unfair rules.
So, think of Ruan Ji as a really cool poet and musician who lived a long time ago in China, and who inspired people to think for themselves and be creative.