Therefore, generally speaking, the meaning of "harmony between man and nature" expressed by the ancients has at least four different meanings. This is also the main viewpoint and basis for modern scholars to explain the so-called "harmony between man and nature". However, there is a problem. Although the relevant records in these ancient books do contain similar meanings or expressions to "the unity of heaven and man", they do not explicitly use the term "the unity of heaven and man", but only express their understanding and views on the relationship between heaven and man.

It is recognized that Zhang Zai, a Neo-Confucianist in the Song Dynasty, really put forward the idea of "harmony between man and nature" at the earliest. It is the famous Mr. Yokogawa who put forward the idea of "making a heart for heaven and earth, making a life for the people, connecting the past with the future, and opening peace for all generations". Of course, Mr. Hengqu's explanation of "the unity of man and nature" is not his first creation, but also the induction and refinement of the thoughts of former sages. However, it was in his book Zhengmeng-Ganzhipian that Zhang Zai first explicitly put forward and used the term "harmony between man and nature". His original words were, "Confucianism is sincere because of Ming, and sincere because of Ming, so heaven and man are one, and they are sanctified because of learning, and they get heaven without leaving people." In short, what he means is that honesty belongs to heaven and Ming belongs to people. Because Ming is sincere, because sincerity is sincere, that is, heaven and humanity are causal, so "heaven and man are one."