A copper coin also has different meanings. Does anyone know what it means?

The ancients in China said, to be a man, we should cultivate both inside and outside. I used to think that roundness is smooth, and I thought it was hypocritical to be a person like this. However, I didn't know its true meaning until I read the Book of Changes by Ceng Shiqiang some time ago. The so-called inside and outside circle means one inside and one outside, one yang and one yin. On the inside, we should have principles, on the side, quality, on the outside, doing things, and on the outside, tact. In other words, we should have the principle of being a man in our heart and a flexible way of doing things outside. Being a man really needs to be internal, because you have principles in your heart, so you won't do things indiscriminately. I remember my colleagues said I was a very soft person. At that time, I only felt that I was too honest and inferior. I didn't realize that I had no principles until I read the Book of Changes. Without principles, I will become a bad person or give others a very casual feeling. If I am such a person, others will not respect you. Therefore, being a man must have principles, and when it is time to say "no", you must say it. China people are more face-saving, especially northerners. They are embarrassed to refuse others. The more they live for "face", the more tired they are. Therefore, when faced with opportunities, we should learn to fight for them; Learn to refuse in the face of temptation; Learn to give up in the face of vanity. Only principled people can stand up and speak, speak on the floor and be modest. The so-called excircle, the circle here means round, not smooth. Externality is relative to internal. External refers to diplomacy here, that is, communication now, and circle refers to a way of doing things. If the outside is square, you can't get along with others easily because you are too sharp to tolerate others. Therefore, it must be cylindrical, because only a circle can roll. Just like the tires of a car, you can only move forward by rolling. The inner and outer circles are the same as the outer softness and the inner rigidity, and the two should be combined with yin and yang.