The painter who draws merely by practice and by eye, without any reason, is like a mirror which copies every thing placed in front of it without being conscious of their existence.
Leonardo da VinciO speculators about perpetual motion, how many vain chimeras have you created in the like quest? Go and take your place with the seekers after gold.
Leonardo da VinciYou will never have a greater or lesser dominion than that over yourself...the height of a man's success is gauged by his self-mastery; the depth of his failure by his self-abandonment. ...And this law is the expression of eternal justice. He who cannot establish dominion over himself will have no dominion over others.
Leonardo da VinciDemetrius was wont to say that there was no difference between the words and speech of the unskilled and ignorant and the sounds and rumblings caused by the stomach being full of superfluous wind. This he said, not without reason, for, as he held, it did not in the least matter from what part of them the voice emanated, whether from the lower parts or the mouth, since the one and the other were of equal worth and importance.
Leonardo da Vinci