What do you mean by 'separation'? Listener question

And now I recall another thing I would love to hear you speak about again, and that is "separation". What is it, when you use this word what do you really mean? What is not separated from what. I think I know mostly but I remember months ago when you spoke about it I saw something new (but I do not quite remember). And I love that you all the time find new ways of explaining things.