"Everyone makes mistakes in life, but that doesn't mean they have to pay for them for the rest of their lives. Sometimes wise people make foolish  choices. It doesn't mean they're foolish; it means they're improving!" Sometimes mistakes mean something that you are trying new things. It's good to try new things. Because when you are trying new things, you are growing. If you never have a try, you will never make progress. Look around you, everything you see is the result of someone trying new things. I remember clearly what life was like back in 2006. I was 17 years old and in a really bad place. In a chemistry 1ab, I was doing an experiment . I tried twenty times, but I couldn't succeed. So I decided to stop doing the experiment. I felt a little unhappy. Mr. Green seemed to understand my thought. He touched my head with a smile, "Young man, you have done a lot and you've got a lot. At least you know that there are twenty ways you can't use to do this experiment." After hearing the words, I became excited again. I kept doing the experiment and at last I did succeed. What did Mr. Green want to do with those words?
To show how foolish the writer was. To show how strict the teacher was. To encourage the writer to go on making mistakes. To encourage the writer to go on doing the experiment.