In life, some things should be remembered forever, while others are best forgotten. It is a kind of wisdom to know what to remember and what to forget. Remember what should be remembered and forget what should be forgotten, and your life will be happy and peaceful; on the contrary, if you keep thinking about what you should forget and can't remember what you should remember, your life will be overcast.
what the author tells us to do in the world?
Remember what should be remembered and forget what should be forgotten.