Gottfried Wilhelm Leibniz — "Nihil est sine ratione. There is nothing without a reason."

"I maintain that the monads, which are the true atoms of nature, have no windows through which anything could enter or depart."

"There are never in nature two beings, which are precisely alike, and in which it is not possible to find some difference which is internal, or based on some intrinsic quality."

"Every substance is as a world apart, independent of everything else except God."

"The soul is a living mirror of the universe."

"Certainly the condition of our affairs [in Europe], slipping as we are into ever greater corruption, seems to be such that we need missionaries from the Chinese who might teach us the use and practice…"