Painting is concerned with the ten things you can see: these are darkness and brightness, substance and color, form and place, remoteness and nearness, movement and rest.
Leonardo da VinciThose who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain whether he is going. Practice must always be founded on sound theory, and to this Perspective is the guide and the gateway; and without this nothing can be done well in the matter of drawing.
Leonardo da VinciExperience never misleads; what you are misled by is only your judgment, and this misleads you by anticipating results from experience of a kind that is not produced by your experiments.
Leonardo da Vinci