External perception of the world implies the detection of the objects to fix. This detection is ensured by the visual field and then by the movement of the eyes that allows localization adjustment : the image of the observed object is pictured on a part of the retina presenting the maximum of sensitivity for details resolution and colours, that is on the macula. Each eye transmits an image to the brain but only one image is perceived : it is the resulting binocular vision. All the process is identical to an image formation by one equivalent cyclopean eye localized between the two eyes at the same height but lightly inside the head. The most important and basic law of the binocular vision is to superpose the to retinas of the eyes at the level of this unique eye or better it the level of the occipital cortex. Binocular vision, starting from to retinal images, gives birth to a new perception with different properties the third dimension is the new sensation which is not in the least suggested in monocular vision.