All images reveal and make perceptible those things which are hidden. For example, a man does not have immediate knowledge of invisible things, since the soul is veiled by the body. Nor can man have immediate knowledge of things which are distant from each other or separated by place, because he himself is limited by place and time. Therefore the icon was devised that he might advance in knowledge, and that secret things might be revealed and made perceptible. Therefore, icons are a source of profit, help, and salvation for all, since they make things so obviously manifest, enabling us to perceive hidden things. Thus, we are encouraged to desire and imitate what is good and to shun and hate what is evil.
-St. John Damascene-