even if there is delicious food, you won't know its sweetness until you taste it. Even if there is the best truth, if you don't study, you won't know its benefits. Therefore, only after studying will you know your own shortcomings, and only after teaching others will you know that you also have some inadequacies. Know your own shortcomings, so that you can know how to reflect on yourself; Know what you don't understand, so as to encourage yourself. So: "Teaching and learning are mutually reinforcing. Teaching others can also increase your knowledge. " It is said in "Redemption": "Teaching is half the learning. "Probably said is this truth.