The significance of the mental conflict can be defined in another way, thus: in order to become pathogenic _external_ privation must be supplemented by _internal_ privation. When this is so, the external and the internal privation relate of course to different paths and different objects; external privation removes one possibility of satisfaction, internal privation tries to exclude another possibility, and it is this second possibility which becomes the debatable ground of the conflict. I choose this form of presentation because it contains a certain implication; it implies that the internal impediment arose originally, in primitive phases of human development, out of real external obstacles. But what are these forces out of which the prohibition against the libidinal longings proceeds, the other parties in the pathogenic conflict? Speaking very broadly, we may say that they are the non-sexual instincts. We include them all under the name ‘_Ego-instincts_’; analysis of the transference neuroses offers no adequate opportunity for further investigation of them; at most we learn something of them from the resistances opposed to the analysis. The pathogenic conflict is, therefore, one between the Ego-instincts and the sexual instincts. In a whole series of cases it looks as though there might also be conflict between various purely sexual impulses; at bottom, however, this is the same thing, because of the two sexual impulses engaged in a conflict one will always be found ‘consistent with the Ego’ (_ichgerecht_) while the other calls forth a protest from the Ego. It remains, therefore, a conflict between Ego and sexuality. Over and over again when psycho-analysis has regarded something happening in the mind as an expression of the sexual instincts indignant protests have been raised to the effect that other instincts and other interests exist in mental life besides the sexual, that one should not derive “everything” from sexuality, and so on. Well, it is a real pleasure for once to be in agreement with one’s opponents. Psycho-analysis has never forgotten that non-sexual instincts also exist; it has been built upon a sharp distinction between sexual instincts and Ego-instincts; and in the face of all opposition it has insisted, _not_ that they arise from sexuality, but that the neuroses owe their origin to a _conflict_ between Ego and sexuality. It has no conceivable motive in denying the existence or the significance of the Ego-instincts while it investigates the part played by sexual instincts in disease and in life generally. Only, psycho-analysis has been destined to concern itself first and foremost with the sexual instincts, because in the transference neuroses these are the most accessible to investigation, and because it was obliged to study what others had neglected.