"A calm mind is clear, but a calm mind is constant" is a famous saying from The Mean. The Doctrine of the Mean is one of the traditional Confucian classics, and it is a theoretical work about self-cultivation, managing the country and the world. The book emphasizes the "golden mean", that is, to avoid going to extremes and maintain a state of inner balance and stability. On this basis, we can achieve lasting self-cultivation, governance, and peace in the country.

The Doctrine of the Mean, compiled by Xunzi, is a traditional Confucian classic, which is a theoretical work on self-cultivation, managing the country and the world.