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.

Everything that is possible demands to exist.

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.

Taking mathematics from the beginning of the world to the time when Newton lived, what he had done was much the better half.

Men act like brutes in so far as the sequences of their perceptions arise through the principle of memory only, like those empirical physicians who have mere practice without theory.

I do not believe that a world without evil, preferable in order to ours, is possible; otherwise it would have been preferred. It is necessary to believe that the mixture of evil has produced the greatest possible good: otherwise the evil would not have been permitted. The combination of all the tendencies to the good has produced the best; but as there are goods that are incompatible together, this combination and this result can introduce the destruction of some good, and as a result some evil.

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