It should be pointed out that our eyes don't actually see objects, or things. They are receptors of the visible light that is either given off or reflected off of them. What happens is the light being reflected off an object is collected by the eye. It enters the eye through the pupil, a small round opening in the middle of the colored part of the eye, called the iris. The light passes through a lens, which focuses the light through the body of the eye to the back part of the eye, a blackish area called the retina. The retina is full of small receptor cells called rods and cones which pick up the stimulation of the light and feed it along to the optic nerve, which exits the back of the eye and feeds directly to the brain. The brain receives and interprets the nervous sensation fed to it, and directs the body's responses to what it "sees" appropriately. The images focused on the back of the eye are inverted, but the brain is used to seeing objects presented to it in that orientation and makes an adjustment in the interpretation.