Experience is not all that is and its nature is revealed in its relations to what is wholly other than experience. Then experience is the relation to what is not experience. It makes no sense for the relation to be between what is not experience and the relation to what is not experience. (And if it were how would experience locate what it is not in order to be its relation to it?) So it must be that experience is the relation of one thing that is not experience to another thing that is not experience, being as if were the interface between the two. As for those two others, their relation to each other precedes experience, or they have no such relation being undifferentiated and experience marks their separation out of this undifferentiatedness. How could this breach be effected? Not by what is not experience since it knows no difference, but only out of a sort of usurpation by experience, a catastrophe in the heart of the undifferentiated, the realisation of a wholly heterogenous potentiality. This notion answers to the two great unknowns of experience, what it is that witnesses and what it is that is witnessed.