Chengyu are special sayings that come from Chinese literature and history. They are like mini stories that are used to express ideas. Even though they are short, they make it easy to understand an idea or describe a certain situation. For example, if someone wants to say that someone is not being honest, they could say “zai hou mian bu ke bi.” That literal translation is “on the back it is not changeable”. This chengyu is from an ancient story and means that people shouldn’t try to hide their true feelings.