There is nothing without reason.

But in simple substances the influence of one monad over another is ideal only.

The pleasure we obtain from music comes from counting, but counting unconsciously. Music is nothing but unconscious arithmetic.

Every mind has a horizon in respect to its present intellectual capacity but not in respect to its future intellectual capacity.

There is nothing waste, nothing sterile, nothing dead in the universe; no chaos, no confusions, save in appearance.

It is necessary to believe that the mixture of evil has produced the greatest possible good: otherwise the evil would not have been permitted.

Music is a hidden arithmetic exercise of the soul, which does not know that it is counting.