Cheng Yi said in "Mr. Ming Dow's Tomb Watch": "Without the Duke of Zhou, the sage's way will not work; Monk died, but the sage's knowledge did not pass down. Without Tao, there will be no good governance, no learning, and no true Confucianism for thousands of years. ...... After Mr. (Cheng Hao) was born 1,400 years ago, he learned from the heritage and will also learn from the people. " Cheng Yi inherited Mencius' orthodoxy from his brother Cheng Hao and erased Xun Qing, Wang Tong, Han Yu and others. Here, Cheng Yi made a preliminary definition of Taoism. He explained Tao and learning separately, and interpreted it as the sage's Tao with Duke Zhou as the last representative and the sage's learning with Mencius as the last representative. The former belongs to the political category, while the latter belongs to the academic category. In the eyes of Confucianism, a Confucian engages in politics when he goes out and gives lectures when he is in office. His official career is nothing more than these two things. However, although there are two items, the content is one. Li Xinchuan's Preface to Tao Sheng said: "A husband's Tao is learning, and learning is Tao, but Cheng Zi's words are different. Why? It is also a matter of sages to cover the righteousness to become the Tao; It is also a matter of sages to learn the Tao. If you don't learn from Tao, you can't learn from Tao. Therefore, "learn to love others", the sage thinks this is training, and advocates Ming Dow to learn. Sages are their own responsibilities and never disagree. " The political purpose of Confucianism is to follow the path of saints, but if we can't "follow the path", we will settle for the second best. But will spread the knowledge of sages to people for the sake of "Ming Dow", and expect future generations to do it according to time. By the Southern Song Dynasty, the word "Tao" had not been explained separately. For example, Lu Jiuyuan said, "The decline of Ji Zhou is impossible; Mencius' absence is unknown. " (Collected Works of Lu Jiuyuan, page 158), while Zhu further defined Taoism. He said in the preface to The Mean: "What is the Mean? Zi Zisi is worried about the loss of Taoism. Since ancient times, the Holy Spirit has stood in the sky, and the spread of orthodoxy has come from itself. When seen in the classics, it is' allow to hold the title', and the reason why Yao granted Shun is also; The human heart is only in danger, and the Tao heart is only tiny, but the essence is unique and dumbfounded. Shun also gave it to. "The" secret letter "revealed by Zhu by the ancient sages is the 16-character in Shangshu Dayu Mo, which is also the" 16-character heart biography "in Neo-Confucianism. Zhu defined Tao with the heart of Tao, so the Southern Song Dynasty said: "The name of Tao did not exist in ancient times, but has developed today. Therefore, Zhu's preface to The Doctrine of the Mean is almost the same as that of Taoism, so it is deeply worried by later generations. "In view of this, Wang Tingzhen's definition of Neo-Confucianism (Taoism) in Qing Dynasty is:" Yuting inherited Taoism with the sixteen-character mind method, while Neo-Confucianism inherited later generations. The learning of scholars is also orthodox. " (Preface to the Complete Works of Xiangshan) defines Taoism (Neo-Confucianism) from the perspective of Taoism, forming the ideological core of Taoist school (including Zhu Cheng Neo-Confucianism and Wang Lu Neo-Confucianism).