作者 Sigmond Freud 
译者 M.Andre 
In my recently published work, The Ego and the Id(1923b), I have proposed a differentiation of the mental apparatus, on the basis of which a number of relationships can be represented in a simple and perspicuous manner. As regards other points - for instance, in what concerns the origin and role of the super-ego - enough remains obscure and unelucidated. Now one may reasonably expect that a hypothesis of this kind should prove useful and helpful in other directions as well, if only to enable us to see what we already know from another angle,to group it differently and to describe it more convincingly. Such an application of the hypothesis might also bring with it a profitable return from grey theory to the perpetual green of experience. 
In the work I have mentioned I described the numerous dependent relationships of the ego, its intermediate position between the external world and the id and its efforts to humour all its masters at once. In connection with a train of thought raised in other quarters, which was concerned with the origin and prevention of the psychoses, a simple formula has now occurred to me which deals with what is perhaps the most important genetic difference between a neurosis and a psychosis: neurosis is the result of a conflict between the ego and its id, whereas psychosis in the analogous outcome of a similar disturbance in the relations between the ego and the external world. 
There are certainly good grounds for being suspicious of such simple solutions of a problem. Moreover, the most that we may expect is that this formula will turn out to be correct in the roughest outline. But even that would be something. One recalls at once, too, a whole number of discoveries and findings which seem to support our thesis. All our analyses go to show that the transference neuroses originate from the ego’s refusing to accept a powerful instinctual impulse in the id or to help it to find a motor outlet, or from the ego’s forbidding that impulse the object at which it is aiming. In such a case the ego defends itself against the instinctual impulse by the mechanism of repression. The repressed material struggles against this fate. It creates for itself, along paths over which the ego has no power, a substitutive representation (which forces itself upon the ego by way of a compromise) - the symptom. The ego finds its unity threatened and impaired by this intruder, and it continues to struggle against the symptom, just as it fended off the original instinctual impulse. All this produces the picture of a neurosis. It is no contradiction to this that, in undertaking the repression, the ego is at bottom following the commands of its super-ego - commands which, in their turn, originate from influences in the external world that have found representation in the super-ego. The fact remains that the ego has taken sides with those powers, that in it their demands have more strength than the instinctual demands of the id, and that the ego is the power which sets the repression in motion against the portion of the id concerned and which fortifies the repression by means of the anticathexis of resistance. The ego has come into conflict with the id in the service of the super-ego and of reality; and this is the state of affairs in every transference neurosis. 
On the other side, it is equally easy, from the knowledge we have so far gained of the mechanism of the psychoses, to adduce examples which point to a disturbance in the relationship between the ego and the external world. In Meynert’s amentia - an acute hallucinatory confusion which is perhaps the most extreme and striking form of psychosis - either the external world is not perceived at all, or the perception of it has no effect whatever. Normally, the external world governs the ego in two ways: firstly, by current, present perceptions which are always renewable, and secondly, by the store of memories of earlier perceptions which, in the shape of an ‘internal world’, form a possession of the ego and a constituent part of it. In amentia, not only is the acceptance of new perceptions refused, but the internal world, too, which, as a copy of the external world, has up till now represented it, loses its significance (its cathexis) - The ego creates, autocratically, a new external and internal world; and there can be no doubt of two facts - that this new world is constructed in accordance with the id’s wishful impulses, and that the motive of this dissociation from the external world is some very serious frustration by reality of a wish - a frustration which seems intolerable. The close affinity of this psychosis to normal dreams is unmistakable. A precondition of dreaming, moreover, is a state of sleep, and one of the features of sleep is a complete turning away from perception and the external world. 
We know that other forms of psychosis, the schizophrenias, are inclined to end in affective hebetude - that is, in a loss of all participation in the external world. In regard to the genesis of delusions, a fair number of analyses have taught us that the delusion is found applied like a patch over the place where originally a rent had appeared in the ego’s relation to the external world. If this precondition of a conflict with the external world is not much more noticeable to us than it now is, that is because, in the clinical picture of the psychosis, the manifestations of the pathogenic process are often overlaid by manifestations of an attempt at a cure or a reconstruction. 
The aetiology common to the onset of a psychoneurosis and of a psychosis always remains the 
same. It consists in a frustration, a non-fulfilment of one of those childhood wishes which are for ever undefeated and which are so deeply rooted in our phylogenetically determined organization. This frustration is in the last resort always an extern alone; but in the individual case it may proceed from the internal agency (in the super-ego) which has taken over the representation of the demands of reality. The pathogenic effect depends on whether, in a conflictual tension of this kind, the ego remains true to its dependence on the external world and attempts to silence the id, or whether it lets itself be overcome by the id and thus torn away from reality. A complication is introduced into this apparently simple situation, however, by the existence of the super-ego, which, though a link that is not yet clear to us, unites in itself influences coming from the id as well as from the external world, and is to some extent an ideal model of what the whole endeavour of the ego is aiming at - a reconciliation between its various dependent relationships. The attitude of the super-ego should be taken into account - which has not hitherto been done - in every form of psychical illness. We may provisionally assume that there must also be illnesses which are based on a conflict between the ego and the super-ego.Analysis gives us a right to suppose that melancholia is a typical example of this group; and we would set aside the name of ‘narcissistic psychoneuroses’ for disorders of that kind. Nor will it clash with our impressions if we find reasons for separating states like melancholia from the other psychoses. We now see that we have been able to make our simple genetic formula more complete, without dropping it. Transference neuroses correspond to a conflict between the ego and the id; narcissistic neuroses, to a conflict between the ego and the super-ego; and psychoses, to one between the ego and the external world. It is true that we cannot tell at once whether we have really gained any new knowledge by this, or have only enriched our store of formulas; but I think that this possible application of the proposed differentiation of the mental apparatus into an ego, a super-ego and an id cannot fail to give us courage to keep that hypothesis steadily in view. 
The thesis that neuroses and psychoses originate in the ego’s conflicts with its various ruling agencies - that is, therefore, that they reflect a failure in the functioning of the ego, which is at pains to reconcile all the various demands made on it - this thesis needs to be supplemented in one further point. One would like to know in what circumstances and by what means the ego can succeed in emerging from such conflicts, which are certainly always present, without falling ill. This is a new field of research, in which no doubt the most varied factors will come up for examination. Two of them, however, can be stressed at once. In the first place, the outcome of all such situations will undoubtedly depend on economic considerations - on the relative magnitudes of the trends which are struggling with one another. In the second place, it will be possible for the ego to avoid a rupture in any direction by deforming itself, by submitting to encroachments on its own unity and even perhaps by effecting a cleavage or division of itself. In this way the inconsistencies, eccentricities and follies of men would appear in a similar light to their sexual perversions, though the acceptance of which they spare themselves repressions. 
In conclusion, there remains to be considered the question of what the mechanism, analogous to repression, can be by means of which the ego detaches itself from the external world. This cannot, I think, be answered without fresh investigations; but such a mechanism, it would seem, must, like repression, comprise a withdrawal of the cathexis sent out by the ego.