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

Virtue is the habit of acting according to wisdom.

It has long seemed ridiculous to me to suppose that the nature of things has been so poor and stingy that it provided souls only to such a trifling mass of bodies on our globe, like human bodies, when it could have given them to all, without interfering with its other ends.

It is a good thing to proceed in order and to establish propositions. This is the way to gain ground and to progress with certainty.

What is is what must be.

Thus God alone is the primary Unity, or original simple substance, from which all monads, created and derived, are produced.

One cannot explain words without making incursions into the sciences themselves, as is evident from dictionaries; and, conversely, one cannot present a science without at the same time defining its terms.