I sometimes see the pervasive vertical pattern as speaking of obscure background systems. If the top layer represents the present and each of the preceding layers represent the past, how far back in time can I see? Each successive receding layer becomes harder to perceive as it fades back in time. If the preceding layers represent the background systems upon which my present rests, how much of this accumulated vision can I really perceive? I cannot view history from my moment in the same way as those that came before me. The background systems, upon which my present life is racked, are to a large extent irretrievable because of their inherent subjectivity. These background systems, upon which my existence is often awkwardly stretched out, are difficult to detect and to describe.