The ray of knowledge changes through the medium through which everything is known. If I wear blue glasses, everything will look blue. When I take off my glasses, I see that everything is white. You say goodbye i say hello doormat. If I put on my glasses, everything is green. I know that everything that appears blue is due to the glasses, so I will not be in illusion any more. But I can just keep wearing glasses and things will continue to appear blue. However, although I will know very well that the soul the being is immortal, the knowledge that the body is the direction of death also continues.