Full Idea
A 'passivist' believes that the tendencies of things to behave as they do can never be inherent in the things themselves; they must always be imposed on them from the outside.
Gist of Idea
For 'passivists' behaviour is imposed on things from outside
Source
Brian Ellis (The Philosophy of Nature: new essentialism [2002], Intro)
Book Reference
Ellis,Brian: 'The Philosophy of Nature: new essentialism' [Acumen 2002], p.3
A Reaction
This is the medieval view, inherited by Newton and Hume, which makes miracles a possibility, and makes the laws of nature contingent. Essentialism disagree. I think I am with the essentialists.