An interesting train of thought now presents itself if we consider the relations of this inhibition of discharge by the second system to the regulation through the principle of pain.  Let us now seek the counterpart of the primary feeling of gratification, namely, the objective feeling of fear.  A perceptive stimulus acts on the primitive apparatus, becoming the source of a painful emotion.  This will then be followed by irregular motor manifestations until one of these withdraws the apparatus from perception and at the same time from pain, but on the reappearance of the perception this manifestation will immediately repeat itself (perhaps as a movement of flight) until the perception has again disappeared.  But there will here remain no tendency again to occupy the perception of the source of pain in the form of an hallucination or in any other form.  On the contrary, there will be a tendency in the primary apparatus to abandon the painful memory picture as soon as it is in any way awakened, as the overflow of its excitement would surely produce (more precisely, begin to produce) pain.  The deviation from memory, which is but a repetition of the former flight from perception, is facilitated also by the fact that, unlike perception, memory does not possess sufficient quality to excite consciousness and thereby to attract to itself new energy.  This easy and regularly occurring deviation of the psychic process from the former painful memory presents to us the model and the first example of psychic repression.  As is generally known, much of this deviation from the painful, much of the behavior of the ostrich, can be readily demonstrated even in the normal psychic life of adults.

By virtue of the principle of pain the first system is therefore altogether incapable of introducing anything unpleasant into the mental associations.  The system cannot do anything but wish.  If this remained so the mental activity of the second system, which should have at its disposal all the memories stored up by experiences, would be hindered.  But two ways are now opened:  the work of the second system either frees itself completely from the principle of pain and continues its course, paying no heed to the painful reminiscence, or it contrives to occupy the painful memory in such a manner as to preclude the liberation of pain.  We may reject the first possibility, as the principle of pain also manifests itself as a regulator for the emotional discharge of the second system; we are, therefore, directed to the second possibility, namely, that this system occupies a reminiscence in such a manner as to inhibit its discharge and hence, also, to inhibit the discharge comparable to a motor innervation for the development of pain.  Thus from two starting points we are led to the hypothesis that occupation through the second system is at the same time an inhibition for the emotional discharge, viz. from a consideration of the principle of pain and from the principle of