In the clinical history of the case we have emphasized the appearance of the prohibition in early childhood as the determining factor; but for the further elaboration of the neurosis this rôle is played by the repression which appears at this age. On account of the repression which has taken place, which is connected with forgetting (amnesia), the motivation of the prohibition that has become conscious remains unknown, and all attempts to unravel it intellectually must fail, as the point of attack cannot be found. The prohibition owes its strength--its compulsive character--to its association with its unknown counterpart, the hidden and unabated pleasure, that is to say, to an inner need into which conscious insight is lacking. The transferability and reproductive power of the prohibition reflect a process which harmonizes with the unconscious pleasure and is very much facilitated through the psychological determinants of the unconscious. The pleasure of the impulse constantly undergoes displacement in order to escape the blocking which it encounters and seeks to acquire surrogates for the forbidden in the form of substitutive objects and actions. For the same reason the prohibition also wanders and spreads to the new aims of the proscribed impulse. Every new advance of the repressed libido is answered by the prohibition with a new severity. The mutual inhibition of these two contending forces creates a need for discharge and for lessening the existing tension, in which we may recognize the motivation for the compulsive acts. In the neurosis there are distinctly acts of compromise which on the one hand may be regarded as proofs of remorse and efforts to expiate and similar actions; but on the other hand they are at the same time substitutive actions which recompense the impulse for what has been forbidden. It is a law of neurotic diseases that these obsessive acts serve the impulse more and more and come nearer and nearer to the original and forbidden act. We may now make the attempt to study taboo as if it were of the same nature as the compulsive prohibitions of our patients. It must naturally be clearly understood that many of the taboo prohibitions which we shall study are already secondary, displaced and distorted, so that we shall have to be satisfied if we can shed some light upon the earliest and most important taboo prohibitions. We must also remember that the differences in the situation of the savage and of the neurotic may be important enough to exclude complete correspondence and prevent a point by point transfer from one to the other such as would be possible if we were dealing with exact copies.