The evidence of psycho-analysis shows that almost every intimate emotional relation between two people which lasts for some time--marriage, friendship, the relations between parents and children[35]--leaves a sediment of feelings of aversion and hostility, which have first to be eliminated by repression. This is less disguised in the common wrangles between business partners or in the grumbles of a subordinate at his superior. The same thing happens when men come together in larger units. Every time two families become connected by a marriage, each of them thinks itself superior to or of better birth than the other. Of two neighbouring towns each is the other's most jealous rival; every little canton looks down upon the others with contempt. Closely related races keep one another at arm's length; the South German cannot endure the North German, the Englishman casts every kind of aspersion upon the Scotchman, the Spaniard despises the Portuguese. We are no longer astonished that greater differences should lead to an almost insuperable repugnance, such as the Gallic people feel for the German, the Aryan for the Semite, and the white races for the coloured. When this hostility is directed against people who are otherwise loved we describe it as ambivalence of feeling; and we explain the fact, in what is probably far too rational a manner, by means of the numerous occasions for conflicts of interest which arise precisely in such intimate relations. In the undisguised antipathies and aversions which people feel towards strangers with whom they have to do we may recognize the expression of self-love--of narcissism. This self-love works for the self-assertion of the individual, and behaves as though the occurrence of any divergence from his own particular lines of development involved a criticism of them and a demand for their alteration. We do not know why such sensitiveness should have been directed to just these details of differentiation; but it is unmistakable that in this whole connection men give evidence of a readiness for hatred, an aggressiveness, the source of which is unknown, and to which one is tempted to ascribe an elementary character.[36]