Our concern will be with two interconnected experiences and the tracks which run back and forth between them: the experience of presence and the experience of... absence. It would benefit us, were we able to indicate their position relative to that large and enormously influential set of tracks which forms the framework on which the fundamental trains of Western thought have run and continue to run. To some extent we can and will do this. But there is a problem which besets our efforts from their start, and we will do well not to proceed further without owning up to it. Only later and in piecemeal ways will we come to terms with it, if we come to terms with it at all.