The psychic process which is admitted by the first system only I shall now call the _primary_ process; and the one resulting from the inhibition of the second system I shall call the _secondary_ process. I show by another point for what purpose the second system is obliged to correct the primary process. The primary process strives for a discharge of the excitement in order to establish a _perception_ identity with the sum of excitement thus gathered; the secondary process has abandoned this intention and undertaken instead the task of bringing about a _thought identity_. All thinking is only a circuitous path from the memory of gratification taken as an end-presentation to the identical occupation of the same memory, which is again to be attained on the track of the motor experiences. The state of thinking must take an interest in the connecting paths between the presentations without allowing itself to be misled by their intensities. But it is obvious that condensations and intermediate or compromise formations occurring in the presentations impede the attainment of this end-identity; by substituting one idea for the other they deviate from the path which otherwise would have been continued from the original idea. Such processes are therefore carefully avoided in the secondary thinking. Nor is it difficult to understand that the principle of pain also impedes the progress of the mental stream in its pursuit of the thought identity, though, indeed, it offers to the mental stream the most important points of departure. Hence the tendency of the thinking process must be to free itself more and more from exclusive adjustment by the principle of pain, and through the working of the mind to restrict the affective development to that minimum which is necessary as a signal. This refinement of the activity must have been attained through a recent over-occupation of energy brought about by consciousness. But we are aware that this refinement is seldom completely successful even in the most normal psychic life and that our thoughts ever remain accessible to falsification through the interference of the principle of pain. This, however, is not the breach in the functional efficiency of our psychic apparatus through which the thoughts forming the material of the secondary mental work are enabled to make their way into the primary psychic process--with which formula we may now describe the work leading to the dream and to the hysterical symptoms. This case of insufficiency results from the union of the two factors from the history of our evolution; one of which belongs solely to the psychic apparatus and has exerted a determining influence on the relation of the two systems, while the other operates fluctuatingly and introduces motive forces of organic origin into the psychic life. Both originate in the infantile life and result from the transformation which our psychic and somatic organism has undergone since the infantile period.