We all see things when light from a source enters our eyes. Light travels from a light source such as a lamp or the Sun. Light sources give out light. Some objects seem bright, but they are only reflecting light from elsewhere.
The eye sees the objects by forming an image on the light sensitive Retina. The Retina is made of millions of tiny cells. These tiny cells send messages to the brain along the OPTIC NERVE. The brain sorts out all the messages and builds up an image.
Retina plays a major role in seeing the objects and brain plays a major role in analyzing the objects.