12.
If we pass from a totally dark place to one illumined by the sun, we are dazzled. In coming from a lesser degree of darkness to light that is not dazzling, we perceive all objects clearer and better: hence eyes that have been in a state of repose are in all cases better able to perceive moderately distinct appearances.
Prisoners who have been long confined in darkness acquire so great a susceptibility of the retina, that even in the dark (probably a darkness very slightly illumined) they can still distinguish objects.
13.
In the act which we call seeing, the retina is at one and the same time in different and even opposite states. The greatest brightness, short of dazzling, acts near