What is Vision?
Vision is the deriving of meaning and direction of action as triggered by light. Vision is much more than sight or how clearly one sees, which is commonly measured and termed acuity and is better called sight. Vision is one's comprehensive ability to organize that which can be seen in such a way that one understands what is seen and can use that understanding to guide and direct one's actions to achieve the things wanted and needed to survive and to enjoy life.
What is vision? Arthur Zajonc catches the essence of the totality of vision in the opening paragraphs of his book, Catching the Light - The Entwined History of Light and Mind. He recounts the life of an 8-year old boy, blind since birth because of cataracts, on whom surgery was performed to restore sight.
"Following the operation, they were anxious to discover how well the child could see. When the boy's eyes were healed, they removed the bandages. Waving a hand in front of the child's physically perfect eyes, they asked him what he saw. He replied weakly, 'I don't know.' 'Don't you see it moving?' they asked. 'I don't know' was his only reply. The boy's eyes were clearly not following the slowly moving hand. What he saw was only a varying brightness in front of him. He was then allowed to touch the hand as it began to move; he cried out in a voice of triumph; 'It's moving!' He could feel it move, and even, as he said, 'hear it move,' but he still needed laboriously to learn to see it move. Light and eyes were not enough to grant him sight. The light of day beckoned, but no light of mind replied within the boy's anxious, open eyes. The lights of nature and of mind entwine within the eye and call forth vision."
Vision is much more than the ability to see small detail at great distances. It is the total ability to organize light input and recognize spatial relationships between things and to build an internal representation of reality. From that internal representation of reality, which is by its very nature incomplete, vision provides the organism with the information necessary to make decisions about which actions to take and in what precise way to execute the chosen action.
To do this the person needs to extract huge quantities of information and data from nearly all parts of the body and use all the sensory input available from the external world. This