The mystery of distance

Every object, however near the eye, has something about it which you cannot see, and which brings the mystery of distance even into every part and portion of what we suppose ourselves to see most distinctly. Stand  in  the  Piazza  di  San  Marco,  at  Venice,  as  close  to  the church as you can, without losing sight of the top of it. Look at the capitals of the columns on the second story. You see that they are exquisitely rich, carved all over. Tell me their patterns: You cannot.  Tell  me  the  direction  of  a  single  line  in  them: You cannot. Yet you see a multitude of lines, and you have so much feeling of a certain tendency and arrangement in those lines, that you are quite sure the capitals are beautiful, and that they are all different from each other. But I defy you to make out one single line in any one of them. Now go to Canaletto's painting of this church,  in  the  Palazzo  Manfrini, taken  from  the very  spot  on  which  you  stood.  How  much  has  he represented  of  all  this?  A  black  dot  under  each capital for the shadow, and a yellow one above it for the light. There is not a vestige nor indication of carving or decoration of any sort or kind.

Very different from this, but erring on the other side, is the ordinary drawing of the architect, who gives the principal lines of the design with delicate clearness and precision, but with no uncertainty  or  mystery  about  them;  which  mystery  being removed, all space and size are destroyed with it, and we have a drawing of a model, not of a building.

(Modern Painters I)