When we look out onto a landscape, the eye typically perceives three distinct sections: the sky above, the earth below, and the living beings that exist between them. Historically, these have been referred to as "heaven-human-earth." However, the term "heaven" carries religious connotations that aren't quite relevant here, and "human" excludes other life forms such as animals and plants, which are equally important in understanding the concept.

The lifecycle of plants was used as a framework to understand how the immaterial world ("the heavens, or sky") interacts with the material world ("earth") to create living things that are a mixture of both ("humanity" or the biosphere). A seed, for instance, embodies the potential to manifest this interplay between heaven and earth, illustrating how invisible forces influence and shape the material world. These forces, which could be observed by their effects but not seen directly, were referred to as "qi" 氣.