 Every creature living between Heaven and earth and within the four seas partakes of the nature [qing 情] of Heaven and earth and the harmony of the Yin and the Yang. Even the greatest sages cannot alter this. How do we know? When they taught about Heaven and earth, they dwelt on the upper and the lower spheres and the four seasons, the principles of Yin and Yang and human nature [ren qing 人情], the phenomena of men and women, birds and animals, and that of the sexes. Even the early kings could not escape from the fundamentals of nature. (Mozi, 6.8; Mei 1929: 26).