《淮南子·本经训》
所谓阴阳二气，承受着天地自然中和之气，形成万物千差万别的形体，含蕴着的和气能化育万物；它伸缩舒卷，深入到无法测度的境域，开始时虚空、终至于盈满，周转于没有终始的时空中。
阴阳者，承天地之和，形万殊之体；含气化物，以成埒类；赢缩卷舒，沦于不测；终始虚满，转于无原。
The so-called qi of Yin and Yang is that which bears the harmonious qi of heaven and earth, forms the myriad different shapes of things, and contains the harmonious qi that can nurture all things; it expands and contracts, penetrates into realms that cannot be fathomed, begins with emptiness and ends with fullness, and moves about in a space-time continuum that has no beginning or end.