Xing (性) mainly referred to human nature in ancient times. The concept of xing has two essential points. First, it refers to the inherent nature of all things, not as a result of nurture. Second, it refers to the common nature of certain kind of things, not the nature of individual things of that kind. Similarly, human nature, too, has two meanings. First, it refers to inherent attributes all people share, including physical features, desires, and consciousness. Second, it is the essential and distinct attribute that distinguishes people from birds and beasts, in other words, human’s moral nature. Scholars throughout history held varied views over the question whether human nature was good or evil. Some believed it was good. Some thought it was evil. Some held that it was neither good nor evil. Some held that human nature could be both good and evil in the same person. Some thought that human nature was good in some people, but evil in others.
To love food and good looks is but human nature. (Mencius)
Human nature is in line with the principles of heaven. (Writings of the Cheng Brothers)