“There is nothing without reason.”

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

I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is in fact in nature.

We may say, that not only the soul (the mirror of an indestructible universe) is indestructible, but also the animal itself is, although its mechanism is frequently destroyed in parts.

There never is absolute birth nor complete death, in the strict sense, consisting in the separation of the soul from the body. What we call births are developments and growths, while what we call deaths are envelopments and diminutions.

Nothing is more important than to see the sources of invention which are, in my opinion more interesting than the inventions themselves.

Justice is charity in accordance with wisdom.

I also readily admit that there are animals, taken in the ordinary sense, that are incomparably larger than those we know of, and I have sometimes said in jest that there might be a system like ours which is the pocketwatch of some enormous giant.

To love is to be delighted by the happiness of someone, or to experience pleasure upon the happiness of another. I define this as true love.

Either there are no corporeal substances, and bodies are merely phenomena which are true or consistent with each other, such as a rainbow or a perfectly coherent dream, or there is in all corporeal substances something analogous to the soul.

Now this connection or adaption of all created things with each, and of each with all the rest, means that each simple substance has relations which express all the others, and that consequently it is a perpetual living mirror of the universe.

The most perfect society is that whose purpose is the universal and supreme happiness.

He who hasn’t tasted bitter things hasn’t earned sweet things.

There is a world of created beings – living things, animals, entelechies, and souls – in the least part of matter…. Thus there is nothing waste, nothing sterile, nothing dead in the universe; no chaos, no confusions, save in appearance.

Philosophy consists mostly of kicking up a lot of dust and then complaining that you can’t see anything.

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

Music is a secret and unconscious mathematical problem of the soul.