To return is to revert to the original [substance]. The original [substance] is the mind of Heaven and Earth. […] Thus although Heaven and Earth are vast, possesssing the myriad things in abondance, where thunder moves and winds circulate, and while there is an infinite variety of changes and transformations, yet its original [substance] is absolutely quiet and perfect non-being. Therefore only with the cessation of activities within Earth can the mind of Heaven and Earth be revealed. If being were to be the mind [of Heaven and Earth], things of different categories will not be able to exist together.

(Wang Bi)