As Joseph Smith and Oliver Cowdery had the veil of their minds removed, and had their eyes open to understanding I believe that they moved, or progressed, from that which was Material, or Physical creation, to the world of the Spiritual or Hidden. They were literally transfigured during these Heavenly manifestations. This process is so beautifully described in a post I found on a Blog called Visions of the Kingdom. The post is called “The Veil, that is to say, his flesh”, go and read it now. You will not be sorry you did.