perception is virtual, like the image in the telescope produced by the passage of the rays of light. But we are justified in assuming the existence of the systems, which have nothing psychic in themselves and which never become accessible to our psychic perception, corresponding to the lenses of the telescope which design the image. If we continue this comparison, we may say that the censor between two systems corresponds to the refraction of rays during their passage into a new medium.

Thus far we have made psychology on our own responsibility; it is now time to examine the theoretical opinions governing present-day psychology and to test their relation to our theories. The question of the unconscious, in psychology is, according to the authoritative words of Lipps, less a psychological question than the question of