To the natural mind, reality is confined to the instant called now; this very moment seems to contain the whole of reality, everything else is unreal. To the natural mind, the past and the future are purely imaginary. In other words my past, when I use the natural mind, is only a memory image of things that were. And to the limited focus of the carnal or natural mind the future does not exist. The natural mind does not believe that it could revisit the past and see it as something that present, something that is objective and concrete to itself, neither does it believe that the future exists.
Extracted From: Thinking Fourth Dimensionally.