O Time, consumer of all things! O envious age, thou destroyest all things and devourest all things with the hard teeth of the years little by little,… - Leonardo da Vinci

Just as courage imperils life, fear protects it.

Take a piece of glass of the size of a half sheet of royal folio paper, and fix it... between your eye and the object you wish to portray. Then move it away until your eye is two-thirds of a braccio away from the piece of glass, and fasten your head by means of an instrument in such a way as to prevent any movement of it whatsoever. Then close or cover up one eye, and with a brush or a piece of red chalk finely ground mark out on the glass what is visible beyond it; afterwards, copy it by tracing on paper from the glass, then prick it out upon paper of a better quality and paint it if you so desire, paying special attention to the aerial perspective.

"There are three classes of people: those who see. Those who see when they are shown. Those who do not see."

Time stays long enough for anyone who will use it.

Poor is the pupil who does not surpass his master

Simplicity is the ultimate sophistication.

Nature is the source of all true knowledge. She has her own logic, her own laws, she has no effect without cause nor invention without necessity