Nothing is necessitated whose opposite is possible. - Gottfried Wilhelm Leibniz

And just as the same town, when looked at from different sides, appears quite different and is, as it were, multiplied in perspective, so also it happens that because of the infinite number of simple substances, it is as if there were as many different universes, which are however but different perspective representations of a single universe form the different point of view of each monad.

[...] we can find no true or existent fact, no true assertion, without there being a sufficient reason why it is thus and not otherwise, although most of the time these reasons cannot be known to us.

For all bodies are in perpetual flux like rivers, and parts are passing in and out of them continually.