Do you not recognize, moreover, what it is that supports these conceptions of the two systems and the relationship between them and consciousness? The door-keeper between the unconscious and the preconscious is nothing else than the _censorship_ to which we found the form of the manifest dream subjected. The residue of the day’s experiences, which we found to be the stimuli exciting the dream, was preconscious material which at night during sleep had been influenced by unconscious and repressed wishes and excitations; and had thus by association with them been able to form the latent dream, by means of their energy. Under the dominion of the unconscious system this material had been elaborated (worked over)—by condensation and displacement—in a way which in normal mental life, i.e. in the preconscious system, is unknown or admissible very rarely. This difference in their manner of functioning is what distinguishes the two systems for us; the relationship to consciousness, which is a permanent feature of the preconscious, indicates to which of the two systems any given process belongs. Neither is dreaming a pathological phenomenon; every healthy person may dream while asleep. Every inference concerning the constitution of the mental apparatus which comprises an understanding of both dreams and neurotic symptoms has an irrefutable claim to be regarded as applying also to normal mental life. This is as much as we will say about repression for the present. Moreover, it is but a necessary preliminary condition, a prerequisite, of symptom-formation. We know that the symptom is a substitute for some other process which was held back by repression; but even given repression we have still a long way to go before we can obtain comprehension of this substitute-formation. There are other sides to the problem of repression itself which present questions to be answered: What kind of mental excitations suffer repression? What forces effect it? and from what motives? On one point only, so far, have we gained any knowledge relevant to these questions. While investigating the problem of resistance we learned that the forces behind it proceed from the Ego, from character-traits, recognizable or latent: it is these forces therefore which have also effected the repression, or at least they have taken a part in it. We know nothing more than this at present. The second observation for which I prepared you will help us now. By means of analysis we can always discover the purpose behind the neurotic symptom. This is of course nothing new to you: I have already pointed it out in two cases of neurosis. But, to be sure, what do two cases signify? You have a right to demand two hundred cases, innumerable cases, in demonstration of it. But then, I cannot comply with that. So you must fall back on personal experience, or upon belief, which in this matter can rely upon the unanimous testimony of all psycho-analysts.