Those who become enamoured of the art, without having previously applied to the diligent study of the scientific part of it, may be compared to mariners who put to the sea in a ship without rudder or compass and therefore cannot be certain of arriving at the wished for port.

I wish to work miracles.

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.

I am never weary of being useful... In serving others I cannot do enough. No labor is sufficient to tire me.

Make yourself a master of perspective, then acquire perfect knowledge of the proportions of men and other animals.

Common Sense is that which judges the things given to it by other senses.

People reveal themselves completely only when they are thrown out of the customary conditions of their life.