Mechanics is the paradise of the mathematical sciences because by means of it one comes to the fruits of mathematics.
Leonardo da VinciWhile you are alone you are entirely your own master and if you have one companion you are but half your own, and the less so in proportion to the indiscretion of his behavior.
Leonardo da VinciAs regards this vice, we read that the peacock is more guilty of it than any other animal. For it is always contemplating the beauty of its tail, which it spreads in the form of a wheel, and by its cries attracts to itself the gaze of the creatures that surround it. And this is the last vice to be conquered.
Leonardo da Vinci