Full Idea
Monads aren't a principle of operation for things outside of themselves.
Gist of Idea
Monads control nothing outside of themselves
Source
Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
Book Reference
Leibniz,Gottfried: 'Philosophical Essays', ed/tr. Arlew,R /Garber,D [Hackett 1989], p.204
A Reaction
This is why Leibniz has got into a tangle, and is proposing his 'substantial chain' to join the monads together. I suspect that he would have dumped monads if he had lived a bit longer.