Explorers of the inner realms, such as the great saint Kabir Sahib and Soami Ji Maharaj have described a series of inner regions of varying lights. They also speak of inner celestial music. As this light and sound current flowed out from God it created different planes. There is the purely spiritual region of Sach Khand. Then there is the supra-causal plane which contains a predominance of spirit and a thin veil of illusion.
Then there is a region in which there are equal parts of spirit and matter known as the causal-plane. The astral plane contains more matter than the causal, and the physical plane on which we live is predominantly matter and less of spirit. Thus the density of matter increased as the current flowed further from God.
Mystics and saints speak of the soul as being of the same spiritual essence as God. The current of light and sound flowing from God is also of that essence. Death of the body will no longer hold any fear for us, for we will see during our lifetime what lies beyond.