In best ways I can explain it -
The background becomes the foreground. The 'space' around everything becomes conscious and you realise what you are looking at - whatever object at all- is reflection of yourself. The space is yourself. Thoughts seem to be a slow echo of yourself experiencing yourself.
I had it full blown two years which altered my conception of the universe and self fundamentally but it faded after sleep.
Something very like it is happening at the moment. Not as strong but definitely the beginnings of the same viewpoint.
What actually is this trance called?