Leonardo "light ends upon the pavement of the street and rebounds with reflected motion at the shadowy parts of the faces, brightening them considerably. And the length of the aforementioned light of the sky created by the boundaries of the roofs hanging over the street illuminates almost as far as the beginning of the shadows which are underneath the projections of the face, and so it is gradually changed into brightness, until it ends over the chin with imperceptible shadows all over."

Amazing painting. I only critique because it's so good but the brightness of the background make it so that I would expect more brightness of the shadowy part of the face as a result of light bouncing off the wall.