God sells us all things at the price of labor.
Leonardo Da Vinci
He only moves toward the perfection of his art whose criticism surpasses his achievement.
Tears come from the heart and not from the brain.
Although nature commences with reason and ends in experience it is necessary for us to do the opposite, that is to commence with experience and from this to proceed to investigate the reason.
There is no object so large but that at a great distance from the eye it does not appear smaller than a smaller object near.
A good painter has two main objects to paint, man and the intention of his soul. The former is easy, the latter hard as he has to represent it by the attitude and movement of the limbs.