Mind, as explained is the cause of all our reactions, emotions. We get attached to things which we perceive . Objects do not by themselves cause neither pleasure nor pain. It is our attachment to them because of the values or importance we assign them that causes either pleasure or pain. One can observe what has caused us pleasure at one point of time will cause us pain or we become indifferent to it. Yet the object remains the same. For instance when I was young I use to take pleasure in riding a bicycle,now I find it to be painful to ride. Similarly the things I use to yearn for have lost their charms for me. But these objects remain the same. My reactions to them have changed.
What is the reason? I have changed,my values, priorities have changed. Physically I have changed, my circumstances have changed. So the change is not from out side but from within.
How is this change Perceived by me? I perceive the change through my Mind. I have lost interest through the instrument Mind. So Mind is the cause for the change in attitudes Attachments.
When one focusses on an object , the Mind is focussed on the object to the exclusion of every thing else . Thus mind does not get attached to pleasure or pain. That the object of Concentration can be Light. So,when one concentrates on the Light to the exclusion of every thing else, he becomes impervious to pleasure or pain and goes beyond them.