 Under the qi theory, all things are constituted by a particular measure, both quantitative and qualitative, of the yin and yang qi energies. For example, heaven is constituted by a particularly clear and refined form of qi, whereas the solidity of earth reflects its “heavier” qi composition. For human beings, each person has been endowed with an allotment of qi from birth, which informs his or her inborn “nature” (xing). In traditional Chinese terms, the qi endowment of an individual may be “thick” or “thin.” How this is understood bears directly on the conception of the ideal ethical or spiritual life and political community.