Colors of the mountains

.......Our visual system merely presented us with a direct image of reality in the way that a mirror reflects whatever is before it, there would be no optical illusions. Optical illusions arise when properties of the visual system are imposed on the raw data of the physical world. Nor can we dismiss such illusions as marginal phenomena. When we look around us we see an entirely colored world, but color is simply a property of the perceiving mechanism. All of us have seen mountains, grey or brown in the light of midday, turn to blue at the sun descends, the perhaps to pink or crimson as the last rays touch them, then finally to black as night falls. Of course the mountains have not really changed color, only the light reflected by them has changed, and these changes in turn interact with our means of perceiving and categorizing differences in wavelengths. But in that case, what are the mountains' 'real' colors" Clearly they cannot have any ~ Page 17