Those 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
Hence, as a general rule, Nature teaches us that an object can never be seen perfectly unless the space between it and the eye is equal, at least, to the length of
he 3 branches of Perspective, which are: the diminution in the distinctness of the forms of the objects; the diminution in their magnitude; and the diminution in their colour.
– I say that when you paint you should have a flat mirror and often look at your work as reflected in it, when you will see it reversed, and it will appear to you like some other painter’s work, so you will be better able to judge of its faults
Therefore you must know, O Painter! that you cannot be a good one if you are not the universal master of representing by your art every kind of form produced by nature.
All other company may be highly mischievous.
And if you must have companionship find it in your studio.
tell you, you will not be able to help often listening to their chatter.
better to study the forms of natural objects
Let no man who is not a Mathematician read the elements of my work
