"It can have its effect only through the intervention of God, inasmuch as in the ideas of God a monad rightly demands that God, in regulating the rest from the beginning of things, should have regard to itself"

In this quote, Leibniz is expressing his belief that individual entities or "monads" can only have an effect on the world if God intervenes to make sure that these entities are taken into account in the grand scheme of things. He argues that each monad has an unique identity and purpose that must be thought about by an all-knowing God who is controling the universe. Essentially, Leibniz is arguing that the universe is purchased and purposeful, with each private entity playing a crucial role in the larger photo.