in any way anatomically. We shall remain on psychological ground, and we shall think ourselves called upon only to conceive the instrument which serves the psychic activities somewhat after the manner of a compound microscope, a photographic or other similar apparatus. The psychic locality, then, corresponds to a place within such an apparatus in which one of the primary elements of the picture comes into existence. As is well known, there are in the microscope and telescope partly fanciful locations or regions in which no tangible portion of the apparatus is located. I think it superfluous to apologise for the imperfections of this and all similar figures. These comparisons are designed only to assist us in our attempt to make clear the complication of the psychic activity by breaking up this activity and referring the single activities to the single component parts of the apparatus. No one, so far as I know, has ever ventured to attempt to discover the composition of the psychic instrument through such analysis. I see no harm in such an attempt. I believe that we may give free rein to our assumptions provided we at the same time preserve our cool judgment and do not take the scaffolding for the building. As we need nothing except auxiliary ideas for the first approach to any unknown subject, we shall prefer the crudest and most tangible hypothesis to all others.
We therefore conceive the psychic apparatus as a compound instrument, the component parts of which let us call instances, or, for the sake of clearness, systems. We then entertain the expectation that these systems perhaps maintain a constant spatial relationship to each other like the different systems of lenses of the telescope, one behind another. Strictly speaking, there is no need of assuming a real spatial arrangement of the psychic system. It will serve our purpose if a firm sequence be established through the fact that in certain psychological occurrences the system will be traversed by the excitement in a definite chronological order. This sequence may experience an alteration in other processes; such possibility may be left open. For the sake of brevity, we shall henceforth speak of the component parts of the apparatus as "Ψ-systems."
The first thing that strikes us is the fact that the apparatus