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.

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

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

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

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.

Thus God alone is the primary Unity, or original simple substance, from which all monads, created and derived, are produced.

We live in the best of all possible worlds