Let us now summarize what understanding we have gained of taboo through its comparison with the compulsive prohibition of the neurotic. Taboo is a very primitive prohibition imposed from without (by an authority) and directed against the strongest desires of man. The desire to violate it continues in the unconscious; persons who obey the taboo have an ambivalent feeling toward what is affected by the taboo. The magic power attributed to taboo goes back to its ability to lead man into temptation; it behaves like a contagion, because the example is contagious, and because the prohibited desire becomes displacing in the unconscious upon something else. The expiation for the violation of a taboo through a renunciation proves that a renunciation is at the basis of the observance of the taboo. 3 We may ask what we have gained from the comparison of taboo with compulsion neurosis and what value can be claimed for the interpretation we have given on the basis of this comparison? Our intrepretation is evidently of no value unless it affords an advantage not to be had in any other way and unless it affords a better understanding of taboo than was otherwise possible. We might claim that we have already given proof of its usefulness in what has been said above; but we shall have to try to strengthen our proof by continuing the explanation of taboo prohibitions and customs in detail. But we can avail ourselves of another method. We can shape our investigation so as to ascertain whether a part of the assumptions which we have transferred from the neurosis to the taboo, or the conclusions at which we have thereby arrived can be demonstrated directly in the phenomena of taboo. We must decide, however, what we want to look for. The assertion concerning the genesis of taboo, namely, that it was derived from a primitive prohibition which was once imposed from without, cannot, of course, be proved. We shall therefore seek to confirm those psychological conditions for taboo with which we have become acquainted in the case of compulsion neurosis. How did we gain our knowledge of these psychological factors in the case of neurosis? Through the analytical study of the symptoms, especially the compulsive actions, the defence reactions and the obsessive commands. These mechanisms gave every indication of having been derived from _ambivalent_ impulses or tendencies, they either represented simultaneously the wish and counter-wish or they served preponderantly one of the two contrary tendencies. If we should now succeed in showing that ambivalence, i.e., the sway of contrary tendencies, exists also in the case of taboo regulations or if we should find among taboo mechanisms some which like neurotic obsessions give simultaneous expression to both currents, we would have established what is practically the most important point in the psychological correspondence between taboo and compulsion neurosis.