32 REFLECTION AND THE FAMILY OF ANGLES
of light (because they are all the same gray). Yet the dierence in the three
subjects is apparent. You have seen it. (If not, try again, and you will, now
that you know we expect you to do so!)
e reason that these subjects, with identical transmission and absorp-
tion, appear dierent is that the subjects reect the light dierently. e
reason you can see the dierences without looking at examples on this page
is that they are part of that visual knowledge you already have stored away
in the occipital lobe of your brain.
In this chapter, we are not going to tell you very many things your brain
does not already know. We will, however, put some of that knowledge into
words. is will make it easy ...