Encountering a notebook or an artefact from the past might trigger an involuntary memory catapulting you into a moment of lost time, but equally likely it might seem as strange as if it belongs to someone else entirely. In either case it is the span of the immediate present that is at stake, or rather the timeless essence of something close and accessible only in the immediate present. This is not a reality but an ideality which is absolutely constant like a mathematical truth - only it is unlike such a truth in seeming to be the only instance of its kind in all of reality. It is both real ad ideal and, in that way, not 'one' but only not two.