2. The Classic of Tao Te Ching, a work before the separation of the pre-Qin philosophers in ancient China, was highly praised by the philosophers at that time and was a philosophical work written by Laozi in the Spring and Autumn Period. The text of Tao Te Ching takes "morality" in the philosophical sense as the main line, and discusses the ways of self-cultivation, governing the country, using troops and keeping in good health, but most of them aim at politics. It is the so-called "inner sage and outer king", known as the king of all classics, with profound meaning and wide tolerance.