Eyes are so much limited to see the things as they are in a whole. Eyes cannot see anything completely without memory. Can you see your face in the mirror? Eyes can see only a single fragment in one time. You can see your nose, ear, lip and all the rest one by one but you cannot see your face. Face is not parts of face. Face is a whole thing.
You can see all these fragments one by one but fragments are not the whole. The whole is a totally different thing. It is not a combination of fragments. When you are looking on a fragment of your face in the mirror, the brain is projecting a picture of your face by putting the stored memories together of all fragments of your face. You think you are looking your whole face but it is just your thought. In reality you are watching projection of your own past memories; and memories are not the actual thing.
Look in the mirror and see this fact now. Watch the whole movement of mind and understand the limitations and intricacies of brain. It is simple but so vital to observe this fact. It will help you to understand the open and hidden parts of your consciousness, structure of a thought and its responses and pettiness.