Full Idea
Primary matter is nothing if considered at rest.
Gist of Idea
Prime matter is nothing when it is at rest
Source
Gottfried Leibniz (Aristotle and Descartes on Matter [1671], p.90)
Book Reference
Leibniz,Gottfried: 'Leibniz Selections', ed/tr. Wiener,Philip P. [Scribners 1951], p.90
A Reaction
This goes with Leibniz's Idea 13393, that activity is the hallmark of existence. No one seems to have been able to make good sense of prime matter, and it plays little role in Aristotle's writings.
Related Idea
Idea 13393 Any entity has the unique property of being that specific entity [Jubien]