In Buddhism, ‘emptiness’ is not nothingness, it is the fluidity of existence. It may be defined as the relativity of things, the transience of things, the totality of things, the ultimate ungraspability of things: emptiness is identical to existence—that is why ‘the whole world doesn’t conceal it’. Clinging to the psychological experience of nonbeing or extinction is what is called the ‘lesser way,’ lacking the unity with the world that is the basis of the ‘greater way.’
Zen Master Dogen.
E.g. Everything is always in flux, everything is moving, and everything is at once giving birth to everything else, as everything is relative to everything else and depends on everything else for its definition. Thus everything is both parent and child of everything else.
We also have (1) Modern physics; (2) The observable fact that everything is made up of other things; and (3) The net of Indra (described elsewhere).
Note: The greater Way includes what is commonly referred to as non-duality, or non-understanding.