Thus there was required a second activity—in our terminology the activity of a second system—which should not permit the memory occupation to advance to perception and therefrom to restrict the psychic forces, but should lead the excitement emanating from the craving stimulus by a devious path over the spontaneous motility which ultimately should so change the outer world as to allow the real perception of the object of gratification to take place. Thus far we have elaborated the plan of the psychic apparatus; these two systems are the germ of the Unc. and Forec, which we include in the fully developed apparatus.
In order to be in a position successfully to change the outer world through the motility, there is required the accumulation of a large sum of experiences in the memory systems as well as a manifold fixation of the relations which are evoked in this memory material by different end-presentations. We now proceed further with our assumption. The manifold activity of the second system, tentatively sending forth and retracting energy, must on the one hand have full command over all memory material, but on the other hand it would be a superfluous expenditure for it to send to the individual mental paths large quantities of energy which would thus flow off to no purpose, diminishing the quantity available for the transformation of the outer world. In the interests of expediency I therefore postulate that the second system succeeds in maintaining the greater part of the occupation energy in a dormant state and in using but a small portion for the purposes of displacement. The mechanism of these processes is entirely unknown to me; any one who wishes to follow up these ideas must try to find the physical analogies and prepare the way for a demonstration of the process of motion in the stimulation of the neuron. I merely hold to the idea that the activity of the first Ψ-system is directed to the free outflow of the quantities of excitement, and that the second system brings about an inhibition of this outflow through the energies emanating from it, i.e. it produces a transformation into dormant energy, probably by raising the level. I therefore assume that under the control of the second system as compared with the first, the course of the excitement is bound to entirely different mechanical conditions. After the second system has finished its tentative mental work, it removes the inhibition and congestion of the excitements and allows these excitements to flow off to the motility.
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.