OF THE 10 ATTRIBUTES OF THE EYE, ALL CONCERNED IN PAINTING.
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. This little work of mine will be a tissue [of the studies] of these attributes, reminding the painter of the rules and methods by which he should use his art to imitate all the works of Nature which adorn the world.
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.