The sense of vision has long fascinated human kind.
In the time of the Greeks, they believed that vision was somewhat analogous to the sense of touch. And what happened is when you open your eyes and you looked at an object there was some visual fire, some visual flux left your eye, went out and touched the object and the sense of vision was in fact the interaction between this emanating flux and the object itself. It was like a long distance sense of touch.
Over time the modern interpretation of the way vision works was developed, and certainly by the Middle Ages I think, it was quite well understood. And the way we understand today is that a scene is illuminated by a light source, in this case the sun. Rays of light fall down onto objects and is reflected into all sorts of different directions, and some of those light rays are reflected into our eye, where they are focused onto photoreceptors and lead to some stimulation to the brain, which we interpret as visual perception.
Humans have been fascinated by the sense of vision for a long time, but it took a while to figure out how it worked. We now understand that illumination falls on an object and some light is reflected into our eye where it is sensed and interpreted by our brain.