Music is the pleasure the human mind experiences from counting without being aware that it is counting.

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.

Reality cannot be found except in One single source, because of the interconnection of all things with one another. I maintain also that substances, whether material or immaterial, cannot be conceived in their bare essence without any activity, activity being of the essence of substance in general.

The world is not a machine. Everything in it is force, life, thought.

The words 'Here you can find perfect peace' can be written only over the gates of a cemetery.

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

Nihil est sine ratione. There is nothing without a reason.