Full Idea
The obvious difference between natural and non-natural things is that each of the natural ones contains within itself a source of change and of stability, in respect of either movement or increase and decrease or alteration.
Gist of Idea
Natural things are their own source of stability through change
Source
Aristotle (Physics [c.337 BCE], 192b14)
Book Reference
Aristotle: 'Physics', ed/tr. Waterfield,Robin [OUP 1996], p.33
A Reaction
This is the reason why Aristotle places so much emphasis on lives, though elements also have persistence in a similar way. We now have atoms and molecules as well.
Related Ideas
Idea 17041 Natural objects include animals and their parts, plants, and the simple elements [Aristotle]
Idea 16508 Things are more unified if the unity comes from their own nature, not from external force [Aristotle]