ance. An effect is equally real with its cause. Before colour can be described in that way it must be set in opposition to something actual, and that is only possible through introjection. The objects apprehended must be regarded as merely representations in our heads, as effects produced by the real external objects. These external objects will constitute reality: the representations will be mere appearance. It is then only a question of consistency how far this view is to be carried—whether the ether, the object and the whole spatial environment including the brain itself, are not also merely representations in us, or rather representations in the representation of my head (‘Vorstellungskopf in meiner Kopfvorstellung’).[1]
While still deferring consideration of the process of introjection, the following observations may be made.[2] When it is asserted that an object produces a perception in us, it is assumed that it acts on the sense-organs and brain, and also upon that inner something, soul or consciousness, which introjection adds. What now is meant by ‘acting on’? It covers the conception of physical causation. There is a continuous causal relation between the object and the resulting process in the brain. By acting on the brain it causes that process. This causal relation will not, however, carry us from the brain-state to consciousness. For when followed further it only leads back again through the muscles to the external world. The empirical fact that our apprehension of the object varies together with the brain-state has led to the quite illegitimate assumption, for which there is no evidence, that it likewise is an effect caused by the object. We transform the merely logical functional relation, according to which our world as a whole and in all its parts varies together with changes in this particular part of itself, into a causal relation between our world conceived as an effect and the brain as its external cause. We duplicate the one given reality into an external world and its internal representation.
The most, then, we can ever do is simply to describe what we actually find as constituting reality.[3] From the absolute standpoint we describe the object just as it is presented, and from the relative point of view, while considering it as a term in a relation whose other term is the self, we must also still describe it just as it exists for us. In the latter case, however, the observer no longer asserts without limitation ‘the cinnabar is red’ (or ‘is black,’ as the case may be), but
