At death, the spirit leaves the physical body and the silver cord is severed.
As the spirit's vibrations automatically begin to accelerate in preparation for advancing to the spirit world, darkness begins to envelop the soul. When it has reached the correct level of vibration it is still standing in the same proximity as the dead physical body but is just now on a different level of vibration and cannot see the physical world anymore. It can see the entrance to the spirit world in the distance, which would not be unlike standing in a tunnel and seeing the light at the end of it.
As the spirit moves towards the light it passes through the first two levels of spirit usually very quickly, and is unaware of passing by them.Usually because the passing spirit does not know of their existence.
This darkness that envelops the soul is a 'mist' that separates our two worlds. It is a mist of negative vibrations that has accumulated through time and is continuing to do so. Every time someone or something is harmed that mist becomes ever so slightly thicker and denser - the worse the deed, proportionately thicker the adding to the mist. After all it does make sense that all those negative vibrations must go somewhere - they cannot just disappear as if it never happened.
The reason why it has always been described as a tunnel is because of the similarity. If you are standing in a tunnel looking toward one of the ends; you are in darkness looking toward a light source. As you move toward that light source it becomes larger and larger until you exit the tunnel. So too it is with the 'spiritual tunnel'; you are standing in the darkness of the mist looking toward the 'opening' of the spirit world - a source of great and wonderous light. As you move toward that light through the mist the light obviously becomes larger and larger still until you reach the entrance to the spirit world. It is not a tunnel, but people can be excused for thinking it is due to the obvious similarities.
