When you close your eyes, you continue to see. It could be the afterimage of a bright scene. It could be the red light that makes it through your eyelids. You never see 'nothing'. In total darkness, more mysterious things appear: strange lights, patterns and images. These are Phosphenes - images that are created within your eyes - or tricks played from within your brain. Vision and perception do not cease in the absence of light.
When the light are bright, we trust our eyes. We believe what we see. Or do we see what we believe. How much of what we observe really is from the outside world? Do we see only what we expect to see?
Our vision is not passive. To see is to interpret; to project our ideas and memories; our fears and hopes onto whatever may be out there.