CHAPTER XI

INTRODUCTION TO THE SCIENTIFIC STUDY OF DEATH

Theory of the immortality of lower organisms—Immortality of the sexual cells in higher organisms—Immortality of the cellular soul—Occurrence of natural death in the case of certain animals—Natural death in the Ephemeridæ—Loss of the instinct of preservation in adult ephemerids—Instinct of life in the aged—Instinct of natural death in man—Death of old men in Biblical times—Changes in the instincts of man and lower animals

From what I have said in the last chapter, it is plain that, perhaps before very long, it will be possible to modify old age. Instead of retaining its existing melancholy and repulsive character, it may become a healthy and endurable process; it may also be that the duration of life will be prolonged. However, it may be asked, what shall we gain by attaining the age of 100 or 120 years instead of 70 or 80, if there still remain for us the appalling fate of the inevitable annihilation of death. Marcus Aurelius said that he who makes a long journey and he who makes it short, alike meet death at the end; and that once they are over, three years or a century are much alike. Such assertions, however, do not take into account the difference in the values we set on a thing at different ages. A man of the age of twenty-five years and one fifty years old reason differently, and are affected differently by the same surroundings. The outlook on life changes in the same individual as he gets on in years. Young people judge of their impressions by comparison with their ideals, and as the latter are very high, they are dissatisfied with things as they really are. They are exacting, and discontented with what they can get out of the real world; grown up people and those of advanced years are more easily satisfied because they have a clearer knowledge of the true value of things. As I have already had occasion to point out in a previous chapter, the young are more inclined to pessimism than the old. We see, then, that appreciation of life changes with age. It is the same with regard to death. It has often been said that life is only a preparation for death. Cicero said, “From our youth upwards we must accustom ourselves to face our last moments without fear. If not, there is an end to peace, since it is quite certain that we must die.” Philosophy has been called the art of preparing for death.

Before considering in what direction science may direct our steps towards solving the problem of death, which in the words of St. Paul is the “last enemy to be destroyed,” let us see how much is known about it.

We are so accustomed to look upon death as something natural and inevitable, that it has long since come to be regarded as inherent in organisms. However, when biologists investigated the matter more carefully, they failed to discover any proof of the accepted doctrine. Observation of members of the lowest grade of animal life, such as infusorians and other protozoa, has shown that these reproduce by simple division, and in a very short time multiply to an astonishing extent. Generation succeeds generation, with the utmost rapidity and without the intervention of death; no single corpse appears in the swarming masses of animalculæ. From such facts, which are extremely easy to confirm, several biologists, and in specially Bütschli and Weismann,[319] have deduced an immortality of the unicellular organisms. When an infusorian has divided, each daughter organism rapidly completes itself and sets about again dividing in the fashion of its parent. The process may be more complicated, as in the cases where a single organism breaks up into several portions each of which contains an essential part of the parent organism. Many unicellular organisms reproduce in such a fashion, and as each animal divides simultaneously into a number of individuals of the new generation, the individuality is destroyed. It is possible to admit with Götte[320] that such a process is natural death, although there is no actual destruction and no corpse.

In any event it cannot be disputed that lower organisms are not subject to the natural death that comes inevitably to man and the higher animals. It has been suggested that the debility of infusorians after a rapid series of divisions, and before conjugation, is to be interpreted as natural death. But the rejuvenescence that follows conjugation is incompatible with such an interpretation. Moreover, when conjugation does not occur, and the debility leads to death, the deaths must be regarded as accidental.

The theory of the immortality of unicellular organisms is now generally accepted. However, there are animals, higher in the scale of life, to which natural death does not come. Among these occur certain forms of considerable complexity, composed of many organs and very many cells, such as many polyps, and some worms, especially annelid worms. Some annelids (Fig. 17) reproduce by transverse divisions very actively. “Throughout the summer,” said E. Perrier,[321] “the Naïdimorpha are devoid of genital organs, and apparently (according to unpublished observations of Maupas), they may be kept alive for several years, and perhaps indefinitely, in this sexless condition.” This certainly may be regarded as a case of immortality due to the indefinite power of regeneration possessed by a complex animal.

The facts that I have cited show that death is not necessarily inherent in living organisms. Naegeli,[322] a well-known German botanist, has asserted even that natural death does not exist in nature. He points out that trees, more than a thousand years old, perish not by natural death, that is to say, by the gradual decay of their vitality, but by some catastrophe.

[Illustration:

FIG. 17.—_Chætogaster_ about to divide into four (from a drawing by M. Mesnil). ]

The age of the famous dragontree of the Villa Oratava at Teneriffe, admired by Von Humboldt, was estimated at several thousand years. Its trunk was hollow, but the huge monster continued to flourish until it was overthrown by a storm. It was only by a catastrophe that the long-lived giant perished. The Baobab is reputed to live for five or six thousand years.

In a recently published essay, Jacques Loeb,[323] a distinguished biologist in Chicago, has made a study of natural death, and has come to the conclusion that there is no good evidence for its existence. He has observed that ripe, but unfertilised eggs of sea hedgehogs (Echini) die a few hours after they have been discharged. Loeb thinks that this may be a case of natural death, but I cannot agree with this opinion, as an egg that has not been fertilised by a spermatozoon may be compared with an organism deprived of its nutrition and so dying of starvation. In both cases death is purely accidental and could have been avoided.

If natural death does exist, it must have appeared on the face of the earth long after the appearance of life. Weismann has suggested that death arose as an adaptation for the advantage of the species, that is to say, in relation to the surrounding conditions of existence, and not as an absolute necessity inherent in the nature of the living substance. He thought that as worn organisms are no longer suited for reproduction or for the struggle for life, natural death was due to natural selection, it being necessary to maintain the species in a vigorous state by weeding out the debased individuals. But the introduction of death for that purpose was superfluous, since the debility caused by old age in itself would eliminate the aged in the course of the struggle for existence. Violent death must have appeared almost as soon as living things came into being. The infusorians and other low organisms, despite their potential immortality, must have been subjected perpetually to violent death, falling victims to larger and stronger organisms. It is impossible to regard natural death, if indeed it actually exists, as the product of natural selection for the benefit of the species. In the press of the world natural death rarely could come into operation, because maladies or the voracity of enemies so frequently cause violent death.

No doubt a certain number of deaths are recorded in statistics as being due to old age, without visible malady. Sometimes decrepit old men feel no pain and seem to fall quietly into their eternal sleep; but autopsy reveals serious lesions of the internal organs. There is reason to believe that even such deaths are in reality violent and are usually caused by infectious microbes. The general effect on the mind produced by examination of the collected facts is not an acceptance of the view that natural death is essentially inherent in living organisms, but the production of a wish to discover if there be any real proof of its existence.

For some time natural death has been ascribed only to the parts of the body that are of use in the individual life. Those cells, the function of which is to secure reproduction of the species, are, like unicellular organisms, potentially immortal. The egg-cell of the female is transformed into a fœtus, and so is the starting-point of the new generation, while the sexual cells of the new generation give rise to the third generation, and so on, in an endless chain of life. The greater number, by far, of the eggs and spermatozoa perish; but their death is not natural but violent, being due to harmful external agencies. An infinitesimal minority of the sexual cells survive indefinitely in the successions of generations.

Scientific proof exists, therefore, that our bodies contain immortal elements, eggs or spermatozoa. As these cells not only are truly alive but exhibit properties that are within the category of psychical phenomena, it would be possible to build up a serious thesis on the immortality of the soul.

Observations on protozoa, and especially on the infusorian group of protozoa, show that these simple beings, each of which is composed of no more than a single cell, possess a high degree of sensibility. They select their food, distinguish living from dead animalculæ,[324] seek out their mates for conjugation, avoid danger, and hunt their prey; in fact, they are in possession of a set of qualities that must be included in psychical phenomena. Although such phenomena are very much lower in the case of the infusorians than in the case of higher animals, it is possible to speak of the soul of protozoa. Moreover, as the body is immortal by reason of its indefinite power of reproduction by division, the soul also of these creatures is immortal. However, the soul is so primitive that it is impossible to speak in definite terms about it.

As the sexual cells of the human body are immortal, like the protozoa, the problem arises if these too be endowed with an immortal soul. Our existing knowledge makes it impossible to doubt that ova and spermatozoa have sensibility in a degree as high as that of the protozoa. The ova shed secretions that arouse the sensibility of the spermatozoa, and the latter, directed by this specific “odour” (the occurrence being known technically as chemotaxis), make their way to the ovum and penetrate it. Some substances, arousing the spermatozoa into activity and movement, attract them, others repel them. The phenomena of chemotaxis were shown for the first time in the case of cryptogams by Pfeffer, the distinguished botanist, and since then the male cells of many plants and different kinds of animals have been proved to possess sensibility.

When ova and spermatozoa succeed in conjugating, they produce an individual of the next generation, to which they transmit what Haeckel has called the “cellular soul.”[325] This soul, then, is really immortal, inasmuch as the bodies of the reproductive cells are immortal.

Although it is true that our bodies contain elements endowed with immortal souls, it by no means follows that our conscious souls are immortal. In an earlier chapter, I have already pointed out that the psychical phenomena of many of the cells of our body and the cellular souls of these are outside our consciousness. We have no consciousness of the perpetual battle waged by the phagocytes against the microbes that endeavour to obtain a foothold in our tissues. None the less the phagocytes are elements endowed with mobility and sensibility and possessing a cellular soul like that of the protozoa.

A woman has no consciousness of the numerous spermatozoa, with their cellular souls, that enter her body, nor of those that fertilise her egg-cells; she is even without consciousness of the much more highly developed soul of the fœtus. A child before birth possesses psychical qualities much more numerous and more perfect than those of the reproductive cells. It is capable of responding to certain sensations and of performing movements. A child, in the later months of its prenatal existence, possesses the senses of touch and taste and, within limits, the sense of sight.[326] This soul is outside the consciousness of the mother. The mother cannot even tell by her consciousness if she bears under her girdle one or two embryonic souls. And so the immortality of the cellular soul has no relation to the problem of death.

It is a common opinion that only the reproductive cells of man and animals are immortal, and that the other elements of the body are mortal, the latter, if they escape violence, dying a natural death. A contrast has been drawn between the mortal cells in which is resident the life of the body and the immortal cells on which the species depends. However, when non-reproductive cells possess the power of regeneration, it is impossible to deny their immortality. When a polyp or a worm reproduces by division, a large number of cells go to form the new individual, and these cells are immortal in the fashion of the infusoria.

Immortal animals occur only among the lower invertebrates. The power of regeneration fades away in the higher ranks of the scale of life. Whilst worms may be divided in several pieces, each piece being capable of regeneration so as to form a new worm, when molluscs are cut they display only a limited capacity for regeneration. If the antennæ of a snail be amputated they will be renewed, but if the whole creature be cut in pieces death follows. Some of the lower vertebrates, such as newts and salamanders, can renew the tail and the limbs, but they cannot reproduce by division. Birds and mammals, the higher vertebrates, have very little power of regeneration, and tail and limbs are never reformed in their cases.

It seems to be the case that the advance in the general organisation of animals has involved a loss in the reproductive capacity of the cells and tissues. Even in the highest animals, some organs, such as the liver, still possess regenerative capacity; but, on the other hand, many cells have lost the power of regeneration completely. The nervous cells, in particular, which are the highest and most perfectly organised elements of the body, cannot reproduce themselves. After their initial appearance in the course of embryonic development, they pass their lives without regenerating or reproducing. In acquiring the highest qualities, that is to say, their psychical activity, they have lost completely the power of reproduction, the distinctive feature of immortal cells. If cells doomed to natural death really exist, it is in the nervous tissues that we must look for them.

[Illustration:

FIG. 18.—Ephemerids. ]

The existence of natural death in the animal world cannot be denied, but it is very rare. The best example is that of the curious insects known universally as ephemerids (Fig. 18). Swarms of these delicate and graceful insects are to be seen in the summer months round lights. The perfect insects emerge from water, in which the six-legged larvæ feed on the organic débris contained in fresh water. The larvæ are not predaceous, and escape from their numerous and hungry foes by agility. They are long-lived, some of them passing two or three years in the mud of streams, and in the end become winged insects after a rapid metamorphosis. Near Paris, anglers have a popular name (_manne_, manna) for one species (_Palingenia virgo_) which emerges in swarms after sundown from the waters of the Seine and Marne. The swarms fly in huge numbers, like heavy snow-flakes, for a very short time, and then fall into the water (Fig. 19). The flight of these insects lasts only an hour or two, and then, in an enfeebled condition, they fall down in vast numbers. They are attracted by the lanterns lighted by fishermen, and are collected to be used as bait. The life in the winged condition is truly ephemeral and lasts no more than a few hours. The structure of the insect is adapted to this short life. The larvæ have powerful jaws, used in the mastication of food; the winged insects possess only vestiges of jaws. They are unable to feed, and so are adapted only for the briefest existence. Their hour of aerial life is devoted to love. As soon as they emerge the males and females unite, and the packets of eggs, which are deposited at once, fall into the water, and in a few weeks the young larvæ hatch out.

The mode of life and the organisation of the adult ephemerids show plainly that they are adapted to natural death. Death comes to them not because they are without food, or because the environment fails to provide something necessary to life, but merely because they emerge from the larval state in a non-viable condition, without the organs necessary to the maintenance of life.

[Illustration:

FIG. 19.—Swarms of _Palingenia virgo_. ]

Once it is granted that natural death actually exists, it is necessary to study its mechanism as closely as the existing state of knowledge permits. To exclude the possibility of the death having to be interpreted as violent, it would be necessary to know that some very rapid infectious disease does not attack these insects as soon as they emerge from the water. This possibility, although remote, must be examined. Instances are known of large numbers of insects dying very rapidly as the result of attack by a species of mould which causes an epidemic. Every one has seen, especially in autumn, dead flies anchored to the window pane by a little tuft of white fluff. As so many individuals die about the same time, we might be disposed to assign the fact to natural death. The actual cause, however, is an infectious and fatal disease caused by a parasitic mould.

The occurrence of some terrible epidemic may be excluded from consideration in the case of ephemerids. I have made investigations which show that such an epidemic does not occur. The bodies of the dying ephemerids contain no microbe which could be the cause of death. Their death must be regarded as natural, as the result of their organisation, as essentially a part of the nature of the insects. Among the cells of their body there are many active phagocytes. Is it possible to attribute death to ravages that these cells may cause among the higher cells and tissues? Microscopic examination, so far from supporting such a possibility, shows that the organs are quite normal in their intimate structure. The brain and central nervous system, the muscles and other organs, show no signs of that invasion by phagocytes found in cases of senile degeneration. In this example of natural death there is certainly no possibility of phagocytic intervention.

Some biologists have suggested that the rapid death of ephemerids and of some other insects is due to debility caused by the great effort of depositing the male and female sexual cells. On this supposition, the case would be analogous to the shock which is sometimes the consequence of a surgical operation. This hypothesis, however, may be excluded, for among the dead ephemerids there are many males that have not united with females. Among ephemerids males are much more numerous than females; many males have no opportunity of undergoing the sexual shock and of emptying the reproductive organs, and these, none the less, die as rapidly as the others.

As yet we do not know if all the tissues of the ephemerids die simultaneously in natural death. Most probably the cells of the nervous centres perish first, and so bring death on the others. The investigation ought to be made.

Death comes to the ephemerids in the midst of love, at the moment when their sexual instincts are satisfied. It would be very interesting to know the sensations of these creatures as they feel death come on them in the act of reproduction. Naturally it would be impossible to obtain a full answer to the question, but many interesting facts regarding it may be ascertained. All the ephemerids, not only those the life of which is so brief, but those that live for several days (_Chloë_, for instance), are extremely easy to capture. It is unnecessary to take them unawares or to use a net as in the case of flies, wasps, and many other insects. Ephemerids may be taken with the fingers in the simplest way, because they offer no resistance and show no desire to escape, although they have six legs and two or four wings. This is not an isolated case, for some other insects (as, for example, winged ants and aphides) allow themselves to be captured with the same carelessness.

Although the adult ephemerids are careless, the wingless larvæ are timid. When a tube is brought near them, among the water plants, with the object of capturing them, they rapidly move off. It often requires much patience and quickness to capture these larvæ (Fig. 20). The instinct of preservation of life displays itself by rapid flight.

[Illustration:

FIG. 20.—Larva of an ephemerid (_Chloërufulum_). ]

It is remarkable that the adult insect has lost the instinct of self-preservation. If it be touched it may move a short distance off, but it does not take to flight although its wings are very large, and its body, which of itself weighs little, is still lighter because the digestive tube is filled with air and not with food. As a rule, an ephemerid that has been touched does not even move off, but allows itself to be captured without any resistance. It would not be accurate to say that the larva’s instinct of self-preservation has been replaced in the adult by an instinct for death; but it must be admitted that the instinct of preservation has been totally lost. The lack of resistance cannot be explained by any defect in the organs of sense. Not only are the eyes of the larval stage fully preserved in the adult, but the adult males have enormous eyes to enable them to recognise the female in the turbulent flight which takes place at the close of the day. Ephemerids of all ages possess well developed tactile organs, and it is thus in spite of a highly organised sensory system that the adults offer no resistance to enemies.

It is no mere accident that the most striking examples of natural death occur among insects, for these creatures display an unusual stability in their cellular structure with a corresponding lack of the power of regeneration, in these particulars resembling man and the higher animals. The cells of the nervous system are very complex, and are well adapted for the highest function, that is to say, the psychical function. These highly endowed cells, however, are devoid of the power of reproduction. Many experiments have been made in relation to this, and it has been proved clearly that in cold-blooded vertebrates the brain and spinal cord with the nerve cells contained in them are capable of regeneration, whilst among mammals only extremely rare cases are known in which there has been any regeneration of the nervous elements. It is to be expected, then, that cases of natural death occur in the higher animals and especially in man. However, no case is known so plain as that presented by the ephemerids. I have already stated that of deaths apparently due to senile debility in man, a large proportion are certainly due to various infectious diseases that affect the old, such as pneumonia and nephritis. Close examination of the tissues confirms this conclusion, for the destruction of the higher elements by phagocytes produces what is really violent death and not a natural death like that of the ephemerids.

Natural death in man is probably a possibility rather than an actual occurrence. Old age is not a true physiological process but exhibits many morbid characters. That being the case, it is not surprising that it seldom ends in natural death. It is probable, however, that natural death occasionally occurs in very old men.

Attempts have been made to estimate the natural limits of human life. Flourens[327] based a calculation on the duration of the period of growth. If the latter be taken as one fifth the natural life, then human life ought to last a century. As centenarians are rare, the vast majority of deaths, which happen before that age has been reached, must be regarded as violent or accidental. The rule of Flourens, however, is arbitrary, and there is no evidence to show that it is exact. Probably in the human race, as in the case of ephemerids, the natural duration of life varies and cannot be expressed by a definite figure. In most cases it ought to be more than a hundred years, and only in rare cases ought it to be much less than that term. Probably there is a variation in the duration of life just as there is a variation of the date of sexual maturity for which rules may be laid down but not without anticipating numerous exceptions.

The existing pathological character of old age vitiates all conclusions as to natural death, and it is still impossible to be exact in speaking of that subject. It is known that certain organs and tissues remain alive for some time after death. In the case of certain infectious diseases, the heart may be removed from a human body more than thirty hours after death, and if placed under proper conditions will renew its life, and beat for several hours. The white corpuscles, the spermatozoa and the cilia of a corpse, may retain their power of movement. Does this also happen in the rare cases of natural death? That question must be answered in the future. The most important question relating to natural death is the following: Is the appearance of natural death in man accompanied by the disappearance of one instinct, the instinct of self preservation, and by the appearance of another instinct, the instinct of death? Do the phenomena of the ephemerids give us any indication as to this? An exact answer is not to be expected. As old age is generally what may be called an unnatural phenomenon, it is extremely rare for persons to approach the age of natural death with their faculties unclouded. I have had under observation a centenarian old woman, who still remembered some incidents of her youth; in her the desire to live was still strong, but her intellectual faculties were partially dim. Moreover, her brain, of which I have already spoken (p. 241), showed a marked degeneration of the nerve cells due to the activity of macrophages.

I have obtained much information about a centenarian who was alive in Rouen in 1900, but a single glance at her photograph was enough to show that she no longer was in full possession of intelligence.[328] She was infirm in many ways. So also, Chevreul, the celebrated chemist, who died at the age of one hundred and three years, showed not the faintest wish for death; he clung to life, but his mental powers had grown weak.

The cases to which I have referred are typical, but there are exceptions worthy of close attention. Tokarski, in the essay on the fear of death, to which I referred in the sixth chapter, quoted the case of a female centenarian who stated as follows: “If you come to live as long as I have lived, you will understand not only that it is possible not to fear death, but to feel the same need for death as for sleep.” A new feeling had come into existence in the very old person, a feeling incomprehensible to those less old. Apparently this was a case in which the instinct of natural death had appeared in a centenarian whose mental faculties had been retained in a sufficiently perfect state.

I wish very much that I had myself been a witness of this old woman’s remarkable instinct in even one case of the many that I have observed. But all that have been pointed out to me as subject to this new desire have turned out to have been possessed of very different ideas. Some were old invalids, weary of pain and ready to exchange the sorrows of life for death, but who would have preferred to be healed and to live on in comfort. When the possibility of recovering health was suggested to them, they showed signs of pleasure and of the renewal of hope.

Investigations that I have made in homes for the aged have led to negative results on this subject. No case showed the slightest sign of the approach of the instinct of death. However, I have learned from Dr. Fauvel of one case to add to the instance noticed by Tokarski. It was the case of an old lady whose health and circumstances were comfortable and who before her death showed a real desire for it and stated it in much the same language as that quoted by Tokarski. In Fauvel’s case, however, the old lady had reached the age of only eighty-five years. It seems probable that this was a second genuine case of the appearance of the instinct of death, and it is therefore interesting to notice that that instinct, like the sexual instinct, is subject to variation in the date of its appearance.

In my search for instances of the instinct of death, I made use of the large collection made by Lejoncourt,[329] but found that the information given by this author was very incomplete as to the mode of life and the last moments of his cases.

The Bible testifies to the frequency of old age in ancient times and to the complete preservation of the faculties in the aged. It also contains some references that may be interpreted as instances of the instinct of death. I may take its account of the death of some of the patriarchs. “And these are the days of the years of Abraham’s life which he lived, an hundred threescore and fifteen years. Then Abraham gave up the ghost, and died in a good old age, an old man, and _full of years_.”[330] “And the days of Isaac were an hundred and fourscore years. And Isaac gave up the ghost, and died, and was gathered unto his people, being old and _full of days_: and his sons Esau and Jacob buried him.”[331] “After this lived Job an hundred and forty years, and saw his sons, and his sons’ sons, even four generations. So Job died, being old and _full of days_.”[332] It is probable that the phrase “old and full of days,” which sounds strange in our ears, simply refers to the instinct of death, developed in well preserved old men who had attained ages of from 140 to 180 years.[333] The Biblical phrase is not merely a commonplace phrase applied to the death of celebrities for the references to deaths of other persons were put in different language. “And these are the years of the life of Ishmael, an hundred and thirty and seven years: and he gave up the ghost and died; and was gathered unto his people.”[334] “And Jacob lived in the land of Egypt seventeen years: so the whole age of Jacob was an hundred forty and seven years.”[335] “And Aaron was an hundred and twenty and three years old when he died in Mount Hor.”[336] “And Moses was an hundred and twenty years old when he died; his eye was not dim, nor his natural force abated.”[337] In only one of these later cases had the individual reached the age of one hundred and forty years, at which age, apparently, the instinct of natural death appeared.

It may seem altogether surprising and improbable to us that an instinct for death should arise in man, since we are imbued with an instinct of an opposite nature. From the facts that I collected in my sixth chapter, it was to be inferred plainly that the desire of life and the fear of death are manifestations of an instinct deep-rooted in the constitution of man. That instinct is of the same order as the instincts of hunger and thirst, of the need of sleep, of movement and of sexual and maternal love. The devotion and care bestowed on their young by female birds and mammals are known universally. And yet these instincts can be reversed. There is no sacrifice of which the mothers are not capable if it serve to save the life or promote the well-being of their offspring. Such devotion is a manifestation of the maternal instinct, which is one of the strongest instincts known to us. And yet that love, so tender and so absolute, lasts only for the time during which the wants of the young need to be satisfied. As soon as the young begin to be independent, the maternal love changes to indifference or to dislike. At the next breeding-period, maternal love reappears again, so that there is a periodic ebb and flow of the instinct.

The new-born babe takes an instinctive delight in the milk of his mother, which seems to him the only good food in the world. As soon as he can show his feelings, his intense satisfaction as he is suckled is plain. But this instinct lasts only during the period of lactation. As soon as the child begins to take different kinds of food, he ceases to be pleased with his mother’s milk, and may dislike it for the remainder of his life. Several adults to whom I have offered human milk would not even taste it, so disgusting did it seem to them. And yet the taste had nothing intrinsically disagreeable in it. Here again is an example of a strong instinct that changes completely.

Children often eat to repletion of some kind of substance, and for long afterwards that substance disgusts them instead of being coveted by them. It is said that apprentices to pastry-cooks and makers of sweetmeats are allowed at first to eat as much as they please. They soon come to have a profound dislike for the sweet things that children like so much.

A mother who adores her child, or a child who is extremely fond of sweetmeats cannot understand how any mother could dislike her offspring or any apprentice have a distaste for sweets. In the same way, human beings full of the desire for life, believe more easily in eternal life than in the possibility of an instinct of death. And yet the instinct of death seems to lie, in some potential form, deep in the constitution of man. If the cycle of human life followed its ideal course according to physiological function, then the instinct of death would appear in its time, after a normal life and an old age healthy and prolonged.

In reality, human life is subject from its very beginning to the pernicious disharmonies in the constitution of man. This evil influence increases with the passing of the years and leads to an old age ruined by abnormalities. It is not surprising that under such circumstances men wish neither to grow old nor to die. Old men, in spite of their attachment to life, do not attain the capacity to know all that is good in it, and die, in the fear of death, without having known the instinct of death. They may be compared with unhappy women who have married before their sexual instincts have awakened and who have died in childbirth, without ever having known the real joy of loving. Formerly, the number of women in such a case was large. In some parts of Abyssinia, girls married when they were still very young and before their physical development was mature. According to Hassenstein,[338] nearly one third of these young women died in childbirth. They quitted life before they had known the true sexual instinct. The advancement of civilisation and of medical knowledge has greatly reduced the number of such unhappy women. We must hope that the progress of knowledge will bring about a similar advance in relation to the instinct of death. With that progress, the number of men who will live until the instinct has been attained will become greater and greater.