For, above all, I hold a notion of possibility and necessity according to which there are some things that are possible, but yet not necessary, and which do not really exist. From this it follows that a reason that always forces a free mind to choose one thing over another (whether that reason derives from the perfection of a thing, as it does in God, or from our imperfection) does not eliminate our freedom.

Nothing is more important than to see the sources of invention which are, in my opinion more interesting than the inventions themselves.

God makes nothing without order, and everything that forms itself develops imperceptibly out of small parts.

Nature does not make leaps.

The past is pregnant with the present.

There is no way in which a simple substance could begin in the course of nature, since it cannot be formed by means of compounding.

Let there be two possible things, A and B, one of which is such that it is necessary that it exists, and let us assume that there is more perfection in A than in B. Then, at least, we can explain why A should exist rather than B and can foresee which of them will exist; indeed, this can be demonstrated, that is, rendered certain from the nature of the thing.