How do we See

The act of seeing is realised in a very progressive way. Light clusters (photons) that travel from the object to the eye pass through the lens in front of the eye where it is broken and falls reversely on the retina at the back of the eye. Here, the impinging light is turned into electrical signals that are transmitted by neurons to a tiny spot called the centre of vision in the back part of the brain. This electrical signal is perceived as an image in this centre in the brain after a series of processes. The act of seeing actually takes place in this tiny spot at the posterior part of the brain which is pitch-dark and completely insulated from light.

Now, let us reconsider this seemingly ordinary and unremarkable process. When we say that "we see", we are in fact seeing the effects of the impulses reaching our eye and induced in our brain after they are transformed into electrical signals. That is, when we say that "we see", we are actually observing electrical signals in our mind.

The "external world" presented to us by our perceptions is merely a collection of the electrical signals reaching our brain. Throughout our lives, these signals are processed by our brain and we live without recognising that we are mistaken in assuming that these are the original versions of matter existing in the "external world".  We are misled because we can never reach the matter itself by means of our senses.

How do We See?

The act of seeing is realised in a very progressive way. Light clusters (photons) that travel from the object to the eye pass through the lens in front of the eye where it is broken and falls reversely on the retina at the back of the eye. Here, the impinging light is turned into electrical signals that are transmitted by neurons to a tiny spot called the centre of vision in the back part of the brain. This electrical signal is perceived as an image in this centre in the brain after a series of processes. The act of seeing actually takes place in this tiny spot at the posterior part of the brain which is pitch-dark and completely insulated from light. 
Now, let us reconsider this seemingly ordinary and unremarkable process. When we say that "we see", we are in fact seeing the effects  of the impulses reaching our eye and induced in our brain after they are transformed into electrical signals. That is, when we say that "we see", we are actually observing electrical signals in our mind. 

All the images we view in our lives are formed in our centre of vision, which makes up only a few cubic centimetres of the volume of the brain. Both the book you are now reading and the boundless landscape you see when you gaze at the horizon fit into this tiny space. Another point that has to be kept in mind is that as we have noted before, the brain is insulated from light; its inside is absolutely dark. The brain has no contact with light itself.

We can explain this interesting situation with an example. Let us suppose that there is a burning candle in front of us. We can sit across from this candle and watch it at length. However, during this period of time, our brain never has any direct contact with the candle’s original light. While we see the light of the candle, the inside of our brain is solid dark. We watch a colourful and bright world inside our dark brain. The same situation applies to all our other senses. Sound, touch, taste and smell are each perceived in the brain as electrical signals.

Therefore by processing the data in the centre of vision and in other sensory centres, our brain, throughout our lives, confronts not the "original" of the matter existing outside us but rather the copy formed inside our brain. It is at this point that we are misled by assuming that these copies are instances of real matter outside us.

From: http://adf.ly/PkxzN