What is is what must be.

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.

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

...a distinction must be made between true and false ideas, and that too much rein must not be given to a man's imagination under pretext of its being a clear and distinct intellection.

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

God, possessing supreme and infinite wisdom, acts in the most perfect manner, not only metaphysically, but also morally speaking, and ... with respect to ourselves, we can say that the more enlightened and informed we are about God's works, the more we will be disposed to find them excellent and in complete conformity with what we might have desired.

Imaginary numbers are a fine and wonderful refuge of the divine spirit almost an amphibian between being and non-being.