Those who, in debate, appeal to their qualifications, argue from memory, not from understanding.
Leonardo da VinciThose 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.
Leonardo da VinciShadow is the diminution alike of light and of darkness, and stands between darkness and light.
Leonardo da Vinci