Sigmund Freud (1856–1939). Beyond the Pleasure Principle. 1922.


OUR discussion so far results in the establishing of a sharp antithesis between the ‘ego-instincts’ and the sexual instincts, the former impelling towards death and the latter towards the preservation of life, a result which we ourselves must surely find in many respects far from adequate. Further, only for the former can we properly claim the conservative—or, better, regressive—character corresponding to a repetition-compulsion. For according to our hypothesis the ego-instincts spring from the vitalising of inanimate matter, and have as their aim the reinstatement of lifelessness. As to the sexual instincts on the other hand: it is obvious that they reproduce primitive states of the living being, but the aim they strive for by every means is the union of two germ cells which are specifically differentiated. If this union does not take place, then the germ cell dies like all other elements of the multicellular organism. Only on this condition can the sexual function prolong life and lend it the semblance of immortality. Of what important happening then in the process of development of the living substance is sexual reproduction, or its forerunner, the copulation of two individual protozoa, the repetition? That question we do not know how to answer, and therefore we should feel relieved if the whole structure of our arguments were to prove erroneous. The opposition of ego- (or death-) instincts and sexual (life-) instincts would then disappear, and the repetition-compulsion would thereupon also lose the significance we have attributed to it.

Let us turn back therefore to one of the assumptions we interpolated, in the expectation that it will permit of exact refutation. We built up further conclusions on the basis of the assumption that all life must die from internal causes. We made this assumption so light-heartedly because it does not seem to us to be one. We are accustomed so to think, and every poet encourages us in the idea. Perhaps we have resolved so to think because there lies a certain consolation in this belief. If man must himself die, after first losing his most beloved ones by death, he would prefer that his life be forfeit to an inexorable law of nature, the sublime [Greek], than to a mere accident which perhaps could have been in some way avoided. But perhaps this belief in the incidence of death as the necessary consequence of an inner law of being is also only one of those illusions that we have fashioned for ourselves ‘so as to endure the burden of existence’. It is certainly not a primordial belief: the idea of a ‘natural death’ is alien to primitive races; they ascribe every death occurring among themselves to the influence of an enemy or an evil spirit. So let us not neglect to turn to biological science to test the belief.

If we do so, we may be astonished to find how little agreement exists among biologists on the question of natural death, that indeed the very conception of death altogether eludes them. The fact of a certain average length of life, at least among the higher animals, is of course an argument for death from inner causes, but the circumstance that certain large animals and giant trees reach a very great age, one not to be computed up to now, once more removes this impression. According to the grandiose conception of W. Fliess all the vital phenomena—and certainly also death—are linked with the accomplishment of certain periods of time, among which there finds expression the dependence of two living substances, one male and one female, upon the solar year. But observations of how easily and extensively the influences of external forces can alter vital manifestations, especially in the plant world, as to their occurrence in time, can hasten or retard them, militate against the rigidity of the formulae laid down by Fliess and leaves at least doubtful the universality of the laws he sought to establish.

The treatment of these themes, death and the duration of life among organisms, in the works of A. Weismann possesses the greatest interest for us. This investigator originated the distinction of living substance into a mortal and an immortal half; the mortal is the body in the narrower sense, the soma, which alone is subject to natural death; while the germ cells are potentially immortal, in so far as they are capable under certain favourable conditions of developing into a new individual, or expressed otherwise, of surrounding themselves with a new soma.

What here arrests our attention is the unexpected analogy with our conception developed along so different a line of thought. Weismann, who is considering living substance morphologically, recognises in it a constituent which is the prey of death, the soma, the body viewed apart from sex or heredity elements, and, on the other hand, an immortal part, the germ-plasm, which serves the purpose of preservation of the species, of propagation. We have fixed our attention not on the living matter, but on the forces active in it, and have been led to distinguish two kinds of instincts: those the purpose of which is to guide life towards death, and the others, the sexual instincts, which perpetually strive for, and bring about, the renewal of life. This sounds like a dynamic corollary to Weismann’s morphological theory.

This appearance of an important correspondence vanishes as soon as we examine Weismann’s pronouncement on the problem of death. For Weismann admits the differentiation between the mortal soma and the immortal germ-plasm only in relation to multicellular organisms; with the unicellular beings the individual and the reproductive cell are still one and the same. The unicellular he thus affirms to be potentially immortal; death appears only among the metazoa, the multicellular. This death of the higher organisms is, it is true, a natural one, a death from inner causes, but it does not depend on an inherent quality of the living substance, is not to be conceived as an absolute necessity based on the nature of life. Death is rather a purposive contrivance, a phenomenon of adaptation to the external conditions of life, because after the differentiation of the corporeal cells into soma and germ-plasm the indefinite prolongation of the life of the individual would have become a quite inexpedient luxury. With the appearance of this differentiation among multicellular organisms death became possible and expedient. Since then the soma of the higher organisms dies after a certain time from internal causes; the protozoa, however, remain immortal. Propagation, on the other hand, was not first introduced with death; it is on the contrary a primordial property of living matter like growth, in which it originated, and life has gone on uninterruptedly from its inception on the earth.

It is easy to see that to concede natural death to the higher organisms does not greatly help our case. If death is a late acquisition of life, then death-instincts traceable to the beginning of life on this planet no longer come into question. Multicellular organisms may continue to die from internal causes, whether defect of differentiation or imperfections of their metabolism; it possesses no interest for the inquiry on which we are engaged. Such a conception and derivation of death certainly more nearly approaches the ordinary human view of it than the unwonted assumption of ‘death-instincts’.

The discussion which has centred round Weismann’s assertations has in my opinion had no decisive result in any direction. Many writers have reverted to the standpoint of Goette (1883) who saw in death the direct consequence of propagation. Hartmann does not regard as the characteristic of death the appearance of a ‘corpse’, a piece of living substance which has ‘died off’, but defines it as the ‘definitive end of individual development’. In this sense protozoa are also subject to death; with them death invariably coincides with propagation, but it is, so to speak, disguised by the latter, for the whole substance of the parent organism may be absorbed directly into the new individuals.

The interest of the inquiry was soon directed towards testing experimentally the asserted immortality of living substance in unicellular beings. An American, named Woodruff, instituted a culture of a ciliated infusorium, a ‘slipper-animalcule’, which reproduces itself by division into two individuals; each time he isolated one of the products and put it into fresh water. He traced the propagation to the 3,029th generation, when he discontinued the experiment. The last descendant of the first slipper-animalcule was just as lively as its original ancestor, without any sign of age or degeneration: if such numbers are convincing, the immortality of protozoa seemed thus experimentally demonstrable.

Other investigators have arrived at other results. Maupas, Calkins, etc., found, in contradiction to Woodruff, that even these infusoria after a certain number of divisions become weaker, decrease in size, lose a portion of their organisation, and finally die if they do not encounter certain invigorating influences. According to this, protozoa die after a phase of senile decay just like higher animals, in direct contravention of what is maintained by Weismann, who recognises in death a late acquisition of living organisms.

Taking the net result of these researches together, we note two facts which seem to afford us a firm foothold. First: if the animalculae, at a time when they as yet show no signs of age, have the opportunity of mingling with each other, of ‘conjugating’—afterwards again separating—then they remain exempt from age, they have been ‘rejuvenated’. This conjugation is doubtless the prototype of sexual propagation of higher organisms: as yet it has nothing to do with multiplication, it is confined to the mingling of the substances of both individuals (Weismann’s Amphimixis). The invigorating influence of conjugation can also be replaced, however, by certain modes of stimulation, changes in the composition of the nutrient fluid, raising of temperature, or shaking. The famous experiment of J. Loeb will be recalled, who by the application of certain chemical stimuli to the ova of sea-urchins brought about processes of division which usually take place only after fertilisation.

Secondly: it is after all probable that the infusoria are brought to a natural death through their own vital process, for the contradiction between Woodruff’s findings and those of others arises from Woodruff having placed each generation in fresh nutrient fluid. When he refrained from doing so he observed, as did the other investigators, that the generations showed signs of age. He concluded that the animalculae were injured by the products of metabolism which they gave off into the surrounding fluid, and was then able to prove convincingly that only the products of its own metabolism had this effect in bringing about the death of the generation. For in a solution over-saturated with waste products of a distantly related species the very same animalculae throve excellently which when allowed to accumulate in their own nutrient fluid inevitably perished. Thus, left to itself, the infusorium dies a natural death from the imperfect disposal of its own metabolic products: perhaps all higher animals die ultimately from the same inability.

At this point the doubt may then occur to us whether any good purpose has been served in looking for the answer to the question as to natural death in the study of the protozoa. The primitive organisation of these forms of life may conceal from us important conditions which are present in them too, but can be recognised only among the higher animals where they have achieved for themselves a morphological expression. If we abandon the morphological point of view for the dynamic, it may be a matter of entire indifference to us whether the natural death of the protozoa can be proved or not. With them the substance later recognised as immortal has not yet separated itself in any way from the part subject to death. The instinctive forces which endeavour to conduct life to death might be active in them too from the beginning and yet their effect might be so obscured by that of the forces tending to preserve life that any direct evidence of their existence becomes hard to establish. We have heard, it is true, that the observations of biologists allow us to assume such death-ward tending inner processes also among the protozoa. But even if the protozoa prove to be immortal in Weismann’s sense, his assertion that death is a late acquisition holds good only of the outward manifestations of death, and does not invalidate any hypothesis as to such processes as impel towards death. Our expectation that biology would entirely put out of court any recognition of the death-instincts has not been fulfilled. It is open to us to occupy ourselves further with this possibility, if we have other reasons for doing so. The striking resemblance between Weismann’s separation of soma and germ-plasm and our distinction between the death and the life-instincts remains unshaken, moreover, and retains its value.

Let us dwell for a moment on this exquisitely dualistic conception of the instinctive life. According to E. Hering’s theory of the processes in living matter there course through it uninterruptedly two kinds of processes of opposite direction, one anabolic, assimilatory, the other katabolic, disintegrating. Shall we venture to recognise in these two directions of the vital processes the activity of our two instinctive tendencies, the life-instincts and the death-instincts? And we cannot disguise another fact from ourselves, that we have steered unawares into the haven of Schopenhauer’s philosophy for whom death is the ‘real result’ of life and therefore in so far its aim, while the sexual instinct is the incarnation of the will to live.

Let us boldly try to go a step further. According to general opinion the union of numerous cells into one vital connection, the multicellularity of organisms, has become a means to the prolongation of their span of life. One cell helps to preserve the life of the others, and the cell-community can go on living even if single cells have to perish. We have already heard that also conjugation, the temporary mingling of two unicellular entities, has a preservative and rejuvenating effect on both. The attempt might consequently be made to transfer the Libido theory yielded by psychoanalysis to the relationship of the cells to one another and to imagine that it is the vital or sexual instincts active in every cell that take the other cells for their ‘object’, partially neutralise their death-instincts, i. e. the processes stimulated by these, and so preserve those cells in life, while other cells do the same for them, and still others sacrifice themselves in the exercise of this libidinous function. The germ cells themselves would behave in a completely ‘narcissistic’ fashion, as we are accustomed to describe it in the theory of the neuroses when an individual concentrates his libido on the ego, and gives out none of it for the charging of objects. The germ cells need their libido—the activity of their vital instincts—for themselves as a provision for their later enormous constructive activity. Perhaps the cells of the malignant growths that destroy the organism can also be considered to be narcissistic in the same sense. Pathology is indeed prepared to regard the kernels of them as congenital in origin and to ascribe embryonal attributes to them. Thus the Libido of our sexual instincts would coincide with the Eros of poets and philosophers, which holds together all things living.

At this point opportunity offers of reviewing the gradual development of our Libido theory. The analysis of the transference-neuroses forced on our notice in the first place the opposition between ‘sexual instincts’ which are directed towards an object and other instincts which we only imperfectly discerned and provisionally described as ‘ego-instincts’. Among the latter those which subserve the self-preservation of the individual had the first claim for recognition. What other distinctions were to be made, it was impossible to say. No knowledge would have been so important for the establishment of a sound psychology as some approximate understanding of the common nature and possible differences of the instincts. But in no department of psychology did one grope more in the dark. Everyone posited as many instincts or ‘fundamental instincts’ as he pleased, and contrived with them just as the ancient Greek philosophers did with their four elements: earth, air, fire and water. Psycho-Analysis, which could not dispense with some kind of hypothesis as to the instincts, adhered to begin with to the popular distinction, typically represented by the phrase ‘hunger and love’. It was at least no new arbitrary creation. With this one adequately covered a considerable distance in the analysis of the psychoneuroses. The conception of ‘sexuality’—and therewith that of a sexual instinct—certainly had to be extended, till it included much that did not come into the category of the function of propagation, and this led to outcry enough in a severe and superior or merely hypocritical world.

The next step followed when Psycho-Analysis was able to feel its way a little nearer to the psychological ego, which was at first known to us only as a repressing, censoring agency, capable of constituting defences and reaction-formations. Critical and other far-seeing minds had indeed for a long time raised objections to the narrowing of the libido concept down to the energy of the sexual instinct as directed to the object. But they omitted to say whence they obtained this fuller comprehension, and failed to deduce anything from it of value for Psycho-Analysis. In the course of more deliberate advance it came under psycho-analytic observation how regularly libido is withdrawn from the object and directed towards the ego (introversion), and through the study of the libido-development of the child in its earliest phases it became clear that the ego is the true and original reservoir of the libido, which is extended to the object only from this. The ego took its place as one of the sexual objects and was immediately recognised as the choicest among them. Where the libido thus remained attached to the ego it was termed ‘narcissistic’. This narcissistic libido was naturally also the expression of the energy of sexual instincts in the analytical sense which now had to be identified with the ‘instincts of self-preservation’, the existence of which was admitted from the first. Whereupon the original antithesis between the ego-instincts and the sexual instincts became inadequate. A part of the ego-instincts was recognised as libidinous: in the ego sexual instincts were found to be active—probably in addition to others; nevertheless one is justified in saying that the old formula, viz. that a psychoneurosis arises out of a conflict between the ego-instincts and the sexual instincts, contained nothing that we should have to reject to-day. Only, the difference of the two kinds of instincts which was supposed originally to be in some kind of way qualitative has now to be defined otherwise, namely on a topographical basis. In particular the transference neurosis, the real object of psychoanalytic study, is still seen to be the result of a conflict between the ego and libidinous investment of an object.

We are the more compelled now to accentuate the libidinous character of the self-preservative instincts, since we are venturing on the further step of recognising the sexual instinct as the Eros, the all-sustaining, and of deriving the narcissistic libido of the ego from the sum of the libido quantities that bring about the mutual adherence of the somatic cells. But we now find ourselves suddenly confronted with this question: If the self-preservative instincts are also of a libidinous kind, then perhaps we have no other instincts at all than libidinous ones. There are at least no others apparent. In that event we must admit the critics to be in the right who from the first have suspected that psycho-analysis makes sexuality the explanation of everything, or the innovators like Jung who, quickly making up their mind, have used ‘libido’ as a synonym for ‘instinctive force’ in general. Is that not so?

This result was at all events one not intended by us. On the contrary, we took as our starting point a sharp distinction between the ego-instincts (= death-instincts) and the sexual instincts (= life-instincts). We were prepared indeed to reckon even the alleged self-preservative instincts of the ego among death-instincts, a position which we have since corrected and withdrawn from. Our standpoint was a dualistic one from the beginning, and is so to-day more sharply than before, since we no longer call the contrasting tendencies egoistic and sexual instincts, but life-instincts and death-instincts. Jung’s libido theory, on the other hand, is a monistic one; that he has applied the term libido to his only instinctive energy was bound to create confusion, but should not have any further effect on us. We suspect that there are in the ego other instincts than those of self-preservation; only we ought to be in a position to demonstrate them. Unfortunately so little progress has been made in the analysis of the ego that this proof becomes extraordinarily difficult of attainment. The libidinous instincts of the ego may indeed be conjoined in a special way with other ego-instincts of which we as yet know nothing. Before ever we had clearly recognised narcissism, the conjecture was already present in the minds of psychoanalysts that the ‘ego-instincts’ had drawn libidinous components to themselves. But these are merely vague possibilities which our opponents will hardly take into account. It remains an awkward fact that analysis up to now has only put us in the position of demonstrating libidinous impulses. The conclusion that therefore there are no others is one to which we do not assent.

In the obscurity that at present shrouds the theory of instinct, we shall certainly not do well to reject any idea that promises to throw light. We have made the antithesis between the life and death instincts our point of departure. Object-love itself displays a second such polarity, that of love (tenderness) and hate (aggression). What if we could succeed in bringing these two polarities into relation with each other, in tracing the one to the other! We have long recognised a sadistic component of the sexual instinct: it can, as we know, attain independence, and as a perversion, dominate the whole sexual trend of a person. In one of the organisations which I have termed ‘pregenital’ it appears as a dominating part-instinct. But how is one to derive the sadistic impulse, which aims at the injury of the object, from the life-sustaining Eros! Does not the assumption suggest itself that this sadism is properly a death-instinct which is driven apart from the ego by the influence of the narcissistic libido, so that it becomes manifest only in reference to the object? It then enters the service of the sexual function; at the oral stage of organisation of the libido, amorous possession is still one and the same as annihilation of the object; later the sadistic impulse separates itself, and at last at the stage of the genital primacy it takes over with the aim of propagation the function of so far overpowering the sex-object as the carrying out of the sexual act demands. One might even say that the sadism expelled from the ego has acted as guide to the libidinous components of the sexual instinct; these later press on towards the object. Where the original sadism experiences no abatement or fusion, the well-known hate-love ambivalence of the love-life is set up.

If the above assumption is justifiable then we have met the challenge of demonstrating an example of a death-instinct—though a displaced one. This conception, however, is far from being evident, and creates a frankly mystical impression. We incur the suspicion of having attempted at all costs to find a way out of an impasse. We may appeal against this verdict by saying that the assumption is no new one, that we have once before made it when there was no question of an impasse. Clinical observations forced upon us the view that the part-instinct of masochism, the one complementary to sadism, is to be understood as a recoil of the sadism on to the ego itself. A turning of the instinct from the object to the ego is, however, essentially the same as a turning from the ego to the object, which is just now the new idea in question. Masochism, the turning of the instinct against the self, would then be in reality a return to an earlier phase of this, a regression. The exposition I then gave of masochism needs correction in one respect as being too exclusive: masochism may also be what I was there concerned to deny, primary.

Let us return, however, to the life-sustaining sexual instincts. We have already learned from the investigation of the protozoa that the mingling of two individuals without consequent partition, just as copulation between two individuals which soon after separate, has a strengthening and rejuvenating effect (v. s. Lipschütz). There is no sign of degeneration in their descendents, and they also seem to have gained the capacity for withstanding for a longer time the injurious results of their own metabolism. I think that this one observation may be taken as a prototype of the effect of sexual intercourse also. But in what way does the blending of two slightly different cells bring about such a renewal of life? The experiment which substitutes for conjugation among protozoa the effect of chemical or even of mechanical stimuli admits of our giving a reply with certainty: it comes about by the introduction of new stimulus-masses. This is in close agreement with the hypothesis that the life-process of an individual leads, from internal causes, to the equalising of chemical tensions: i.e. to death, while union with an individually different living substance increases these tensions—so to speak, introduces new vital differentia, which then have to be again lived out. For this difference between the two there must naturally be one or more optima. Our recognition that the ruling tendency of psychic life, perhaps of nerve life altogether, is the struggle for reduction, keeping at a constant level, or removal of the inner stimulus tension (the Nirvana-principle, as Barbara Low terms it)—a struggle which comes to expression in the pleasure-principle—is indeed one of our strongest motives for believing in the existence of death-instincts.

But the course of our argument is still disturbed by an uneasy feeling that just in the case of the sexual instinct we are unable to demonstrate that character of a repetition-compulsion which first put us on the track of the death-instincts. It is true that the realm of embryonic developmental processes offers an abundance of such repetition phenomena—the two germ cells of sexual propagation and their life-history are themselves only repetitions of the beginning of organic life: but the essential feature in the processes designed by the sexual instinct is nevertheless the mingling of two cells. Only by this is the immortality of the living substance among the higher forms of life assured.

To put it in other words: we have to make enquiry into the origin of sexual propagation and the source of the sexual instincts in general, a task before which the lay mind quails and which even specialists have not yet been able to solve. Let us, therefore, make a condensed selection from all the conflicting accounts and opinions of whatever can be brought into relation with our train of thought.

One view deprives the problem of propagation of its mysterious attraction by representing it as part of the phenomenon of growth (multiplication by division, germination, budding). The arising of propagation by means of germ-cells sexually differentiated might be conceived, in accordance with the sober Darwinian mode of thought, as a way of maintaining and utilising for further development the advantage of the amphimixis which resulted in the first instance from the fortuitous conjugation of two protozoa. ‘Sex’ would not thus be of very ancient origin and the extraordinarily powerful instincts which aim at bringing about sexual union would thereby repeat something which once chanced to happen and since became established as being advantageous.

The same question now recurs as arose in respect of death—namely, whether the protozoa can be credited with anything beyond what they exhibit, and whether we may assume that forces and processes which become perceptible only in the case of the higher animals did first arise in the more primitive. For our purpose the view of sexuality mentioned above helps very little. The objection may be raised against it that it presupposes the existence of life-instincts as already operative in the simplest forms of life, for otherwise conjugation, which works against the expiration of life and makes the task of dying harder, would not have been retained and elaborated, but would have been avoided. If, then, we are not to abandon the hypothesis of death-instincts maintained, we must associate them with life-instincts from the beginning. But we must admit that we are working here at an equation with two unknown quantities. Anything else that science can tell us of the origin of sexuality amounts to so little that this problem may be likened to an obscurity into which not even the ray of an hypothesis has penetrated. In quite another quarter, however, we encounter such an hypothesis, but it is of so fantastic a kind—assuredly a myth rather than a scientific explanation—that I should not venture to bring it forward if it did not exactly fulfil the one condition for the fulfilment of which we are labouring. That is to say, it derives an instinct from the necessity for the reinstatement of an earlier situation.

I refer, of course, to the theory that Plato in his Symposium puts into the mouth of Aristophanes and which deals not only with the origin of the sexual instinct but also with its most important variations in relation to the object. ‘Human nature was once quite other than now. Originally there were three sexes, three and not as to-day two: besides the male and the female there existed a third sex which had an equal share in the two first…. In these beings everything was double: thus, they had four hands and four feet, two faces, two genital parts, and so on. Then Zeus allowed himself to be persuaded to cut these beings in two, as one divides pears to stew them…. When all nature was divided in this way, to each human being came the longing for his own other half, and the two halves embraced and entwined their bodies and desired to grow together again.’

Are we to follow the clue of the poet-philosopher and make the daring assumption that living substance was at the time of its animation rent into small particles, which since that time strive for reunion by means of the sexual instincts? That these instincts—in which the chemical affinity of inanimate matter is continued—passing through the realm of the protozoa gradually overcome all hindrances set to their striving by an environment charged with stimuli dangerous to life, and are impelled by it to form a protecting covering layer? And that these dispersed fragments of living substance thus achieve a multicellular organisation, and finally transfer to the germ-cells in a highly concentrated form the instinct for reunion? I think this is the point at which to break off.

But not without a few words of critical reflection in conclusion. I might be asked whether I am myself convinced of the views here set forward, and if so how far. My answer would be that I am neither convinced myself, nor am I seeking to arouse conviction in others. More accurately: I do not know how far I believe in them. It seems to me that the affective feature ‘conviction’ need not come into consideration at all here. One may surely give oneself up to a line of thought, and follow it up as far as it leads, simply out of scientific curiosity, or—if you prefer—as advocatus diaboli, without, however, making a pact with the devil about it. I am perfectly aware that the third step in the theory of instinct which I am taking here cannot claim the same certainty as the two former ones, viz. the extending of the conception of sexuality and the establishing of narcissism. These innovations were direct translations of observation into theory, subject to no greater sources of error than is inevitable in anything of the kind. The assertion of the regressive character of instinct rests also, it is true, on observed material, namely on the facts of the repetition-compulsion. But perhaps I have over-estimated their significance. At all events there is no way of working out this idea except by combining facts with pure imagination many times in succession, and thereby departing far from observation. We know that the final result becomes the more untrustworthy the oftener one does this in the course of building up a theory, but the precise degree of uncertainty is not ascertainable. One may thereby have made a brilliant discovery or one may have gone ignominiously astray. In such work I trust little to so-called intuition: what I have seen of it seems to me to be the result of a certain impartiality of the intellect—only that people unfortunately are seldom impartial where they are concerned with the ultimate things, the great problems of science and of life. My belief is that there everyone is under the sway of preferences deeply rooted within, into the hands of which he unwittingly plays as he pursues his speculation. Where there are such good grounds for distrust, only a tepid feeling of indulgence is possible towards the results of one’s own mental labours. But I hasten to add that such self-criticism does not render obligatory any special tolerance of divergent opinions. One may inexorably reject theories that are contradicted by the very first steps in the analysis of observation and yet at the same time be aware that those one holds oneself have only a tentative validity. Were we to appraise our speculations upon the life and death-instincts it would disturb us but little that so many processes go on which are surprising and hard to picture, such as one instinct being expelled by others, or turning from the ego to an object, and so on. This comes only from our being obliged to operate with scientific terms, i. e. with the metaphorical expressions peculiar to psychology (or more correctly: psychology of the deeper layers). Otherwise we should not be able to describe the corresponding processes at all, nor in fact even to have remarked them. The shortcomings of our description would probably disappear if for the psychological terms we could substitute physiological or chemical ones. These too only constitute a metaphorical language, but one familiar to us for a much longer time and perhaps also simpler.

On the other hand we wish to make it quite clear that the uncertainty of our speculation is enhanced in a high degree by the necessity of borrowing from biological science. Biology is truly a realm of limitless possibilities; we have the most surprising revelations to expect from it, and cannot conjecture what answers it will offer in some decades to the questions we have put to it. Perhaps they may be such as to overthrow the whole artificial structure of hypotheses. If that is so, someone may ask why does one undertake such work as the one set out in this article, and why should it be communicated to the world? Well, I cannot deny that some of the analogies, relations and connections therein traced appeared to me worthy of consideration.