ABSTRACT
It has been said that all philosophy is Plato rightly understood: it might be said that all theory ofperspective is Leonardo rightly understood. In or about the year 1500. despite the advances achieved in the previous century, he could still note:
A very great vice is I'ound in many painters, that of depicting men's houses and surroundings in such a way that the gates of the city do not come up to the knees of its inhabitants, even thongh they are nearer to the eye of the observer than is the man who indicates that he wishes to enter.
