There is nothing without reason.

The monad, of which we shall speak here, is nothing but a simple substance which enters into compounds; simple, that is to say, without parts.

I hold that it is only when we can prove everything we assert that we understand perfectly the thing under consideration.

Nothing is necessitated whose opposite is possible.

I also take it as granted that every created thing, and consequently the created monad also, is subject to change, and indeed that this change is continual in each one.

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.

It's easier to be original and foolish than original and wise.