Gottfried Wilhelm Leibniz — "The monads are perpetually changing, but they are never destroyed."

"The monads can only be changed by God."

"The universe, if it were not composed of monads, would be a mere aggregate, not a substance."

"It is God who is the ultimate reason things, and the Knowledge of God is no less the beginning of science than his essence and will are the beginning of things."

"I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is actual in nature."

"For since it is impossible for a creature to be perfect, the universe would be even less perfect if it contained only perfect creatures."