Drawing is based upon perspective, which is nothing else than a thorough knowledge of the function of the eye.
Our life is made by the death of others.
Painting is concerned with all the 10 attributes of sight; which are: Darkness, Light, Solidity and Colour, Form and Position, Distance and Propinquity, Motion and Rest.
One day the world will look upon research upon animals as it now looks upon research on human beings.
A painter should begin every canvas with a wash of black, because all things in nature are dark except where exposed by the light.
Nothing can be loved or hated unless it is first understood.
He who is fixed to a star does not change his mind.
Simplicity is the ultimate sophistication.
Learning is the only thing that never disappoints us.
Human subtlety will never devise an invention more beautiful, more simple or more direct than does nature because in her inventions nothing is lacking, and nothing is superfluous.
Every now and then go away, have a little relaxation, for when you come back to your work your judgment will be surer. Go some distance away because then the work appears smaller and more of it can be taken in at a glance and a lack of harmony and proportion is more readily seen.
It had long since come to my attention that people of accomplishment rarely sat back and let things happen to them. They went out and happened to things.
Nothing will be left, Nothing in the air, nothing under the earth, nothing in the waters. All will be exterminated.
All sciences are vain and full of errors that are not born of Experience, the mother of all Knowledge.