The motive power is the cause of all life.

We must doubt the certainty of everything which passes through the senses, but how much more ought we to doubt things contrary to the senses, such as the existence of God and the soul.

Everything proceeds from everything else and everything becomes everything, and everything can be turned into everything else.

The color of the object illuminated partakes of the color of that which illuminates it.

Those who condemn the supreme certainty of mathematics feed on confusion, and can never silence the contradictions of the sophistical sciences which lead to eternal quackery.

Small rooms or dwellings discipline the mind, large ones weaken it.

The length of a man's outspread arms is equal to his height.