§ 4 The Instinct of Life and the Instinct of Death
The greatest discrepancy of this kind is the knowledge of inevitable death without the instinct which makes it longed for.
There are immortal animals. Man is not of the number. He belongs, like all highly organized beings, to the class of beings which have an end. They die from accident or from disease. They perish in the struggle with other animals, or with microbes, or with external conditions. There are certainly very few, if there are any, which die a really natural death. And so it is with man. We see old men gradually declining who appear to doze gently off into the last sleep, and become extinguished without disease, like a lamp whose oil is exhausted. But this is in most cases only apparently so. Besides the fact that the old age to which they seemed to succumb is really a disease, a generalized sclerosis, autopsy always reveals some lesion more or less directly responsible for the fatal issue.
Man, like all the higher animals, is therefore subject to the law of lethality. But while animals have no idea of death and are not tormented by the sentiment of their inevitable end, man knows and understands this destiny. He has with the animals the instinct of self-preservation, the instinct of life, and at the same time the knowledge and the fear of death. This contradiction, this discordance, is one of the sources of his woes.
Whether it be an accident or the regular term of the normal cycle, death always comes too soon. It surprises the man at a time when he has not yet completed his physiological evolution; hence the aversion and the terror it inspires. “We cannot fix our eyes on the sun or on death,” said La Rochefoucauld. The old man does not regard death with less aversion than the young man. “He who is most like the dead dies with most regret.” Man knows that he is not getting his full measure.
Further, all the really natural acts are solicited by an instinct, the satisfaction of which is a need and a joy. The need of death should therefore appear at the end of life, just as the need of sleep appears at the end of the day. It would appear, no doubt, if the normal cycle of existence were fulfilled, and if the harmonious evolution were not always interrupted by accident. Death would then be welcomed and longed for. It would lose its horror. The instinct of death would replace at the wished for moment the instinct of life. Man would pass from the banquet of life with no other desire. He would die without regret, “being old and full of days,” according to the expression used in the Bible in the case of Abraham, Isaac, and Jacob. No doubt there are some analogies to this in the insects which only assume the perfect form for the purpose of procreation and immediately perish in their full perfection. In these animals the approach of death is blended with the intoxication of hymen. Thus we see some of them, the ephemerae, lose at that moment the instinct of life and the instinct of self-preservation. They allow themselves to be approached, taken, and seized, and make no effort at flight.
But what is this full measure of life which is imparted to us? Metchnikoff holds that the ages attributed to several persons in the Bible are very probable. Abraham lived 175 years, Ishmael 137, Joseph 110, Moses 120. Buffon believed in the existence of a ratio between the longevity of animals and the duration of their growth. He fixed it at 7:1. The animal whose development lasts two years would thus have 14 years of life. This law would give us 140 years, but the figure is too high, and Flourens has reduced the ratio to that of 5:1, which would still give us 100 years. Plato died in the act of conversation at 81; Isocrates wrote his Panathenaïcus at 94; Gorgias died in the full possession of his intellect at 107.
To reach the end of the promised longevity we must neither count on the elixir of life nor on the potable gold of the alchemists, nor on the stone of immortality which did not prevent its inventor, Paracelsus, from dying at the age of 58, nor on transfusion, nor on Graham’s celestial bed, nor on King David’s gerocomy, nor on any nostrum or remedy. Contra vim mortis non est medicamen in hortis, said the Salernian school. What Feuchtersleben said is most true, “The art of prolonging life consists in not cutting it short,” and it is a hygiene, but a brilliant hygiene, such as that of which Metchnikoff traces us the future lines, which will realize the desires of nature.
And now shall we find that physiology has solved the enigma proposed by the Sphinx, and that it has answered these poignant questions:—Whence do we come? whither do we go? what is the end of life? The end of life is, to the physiologist as well as to Herbert Spencer, the tendency towards an existence as full and as long as possible, towards a life in conformity with real nature freed from the discordancies which still remain; it is the accomplishment of the harmonious cycle of our normal evolution. This ideal human nature, without discordancies, no longer vitiated as it is at present but improved, will be the work of time and science. Realized at last it will serve as a solid basis for individual, family, and social morality. Healthy youth fit for action; prolonged, adult age, the symbol of strength; normal old age, wise in council, these would have their natural places in harmonious society. “Great actions,” said one of old, “are not achieved by exertions of strength, or speed, or agility, but rather by the prudence, the authority, and the judgment which are found in a higher degree in old age.” The old age of which Cicero here speaks is the ideal old age, regular and normal, and not the premature, deformed, incapable and egoistic old age which results from a pathological condition. At the end of this full life, the old man being full of days, will crave for the eternal sleep and will resign himself to it with joy....
Death, then, “the last enemy that shall be destroyed,” to use the expression of St. Paul, will yield to the power of science. Instead of being “the king of terrors,” it will become after a long and healthy life, after a life exempt from morbid accidents, a natural and longed for event, a satisfied need. Then will be realized the wish of the fabulist:—
“I should like to leave life at this age, just as one leaves a banquet, thanking the host, and departing.”
Has this physiological solution of the problem of death the virtue attributed to it by Metchnikoff? Is it as optimistic as he thinks it is? The instinct of death supervening at the end of a normal and well-filled cycle will no doubt facilitate to the aged their departure on the great voyage. The wrench will no longer exist for the dead. Will it not exist for those who are left behind? And since the instinct of death can only exist about the time at which death is expected, will the young man and the man of ripened years look with less horror than to-day at the law which cannot be escaped, when they are in full possession of the instinct of life, but warned of the inevitability of death?
Footnotes
1 In a thesis presented in 1742 at Montpellier, Bordeu, then only twenty years of age, made game of the tasks imposed by animists on the Soul, “which has to moisten the lips when required;” or, “whose anger produces the symptoms of certain diseases;” or again, “which is prevented by the consequences of original sin from guiding and directing the body.”
2 Reinke, Die Welt als That; Berlin, 1899.
3 In an article on the experimental method recently published in the Dictionnaire de Physiologie, M. Ch. Richet writes as follows:—“We must therefore never cease to carry out comparative experiments. I do not hesitate to say that this comparison is the basis of the experimental method.” It is in fact what was taught by Claude Bernard in maxim and by example. It is no exaggeration to assert that nine-tenths of the errors which take place in research work are imputable to some breach of this method. When an investigator makes a mistake, save in the case of material error, it is almost certainly due to the fact that he has neglected to carry out one of the comparative tests required in the problem before him. The following is an instance which happened since the above pages were written:—Several years ago a chemist announced the existence in the blood serum of a ferment, lipase, capable of saponifying fats—that is to say, of extracting from them the fatty acid. From this he deduced many consequences relative to the mechanism of fermentations. But on the other hand, it has been since shown (April 1902) that this lipase of the serum does not exist. How did the error arise? The author in question had mixed normally obtained serum with oil, and he had noted the acidification of the mixture; he assured himself of the fact by adding carbonate of soda. He saw the alkalinity of the mixture, serum + oil + carbonate of soda, diminish, and he drew the conclusion that the acid came from the saponified oil. He did not make the comparative test, serum + carbonate of soda. If he had done so, he would have ascertained that it also succeeded, and that therefore as the acid did not come from the saponification of the oil, since there was none, its production could not prove the existence of a lipase.
4 Le Dantec has objected to this conception of phenomena common to different living beings. He insists that all phenomena which take place in a given living being are proper to him, and differ, however slightly, from those of another individual. The objection is more specious than real.
5 Mayer’s claim to fame has been disputed. A Scotch physicist, P. G. Tait, has investigated the history of the law of the conservation of energy, which is the history of the idea of energy. The conception has taken time to penetrate the human mind, but its experimental proof is of recent date. P. G. Tait finds an almost complete expression of the law of the conservation of energy in Newton’s third law of motion—namely, “the law of the equality of action and reaction,” or rather, in the second explanation which Newton gave of that law. In fact, it was from this law that Helmholtz deduced it in 1847. He showed that the law of the equality of action and reaction, considered as a law of nature, involved the impossibility of perpetual motion, and the impossibility of perpetual motion is, in another form, the conservation of energy.
At a meeting of the Academy of Science, at Berlin, 28th March 1878, Du Bois-Reymond violently attacked Tait’s contention. The honour of having been the first to conceive of the idea of energy and conservation was awarded to Leibniz. Newton had no right to it, for he appealed to divine intervention to set the planetary system on its path when disturbed by accumulated perturbations. On the other hand, Colding claims to have drawn his knowledge of the law of conservation from d’Alembert’s principle. Whatever may be the theoretical foundations of this law, we are here dealing with its experimental proof. According to Tait, the proof can no more be attributed to R. Mayer than to Seguin. The real modern authors of the principle of the conservation of energy, who gave an experimental proof of it, are Colding, of Copenhagen, and Joule, of Manchester.
6 It must be added that the absolute rigour of this law has been called in question in recent researches. It would only have an approximate value.
7 The dyne is the force which applied to the unit of mass produces a unit of acceleration.
8 These words spoil the statement, for time has nothing to do with it.
9 We therefore notice that the measures of force and work bring in mass, space, and time. The typical force, weight, is given by w = mg. On the other hand, we have by the laws of falling bodies v = gt; s = 1∕2gt2; whence g = 2s∕t2; w = m(2s∕ t2); or, if F be the force, M the mass, L the space described, and T the time, we have F = MLT-2, which expresses what are called the dimensions of the force—that is to say, the magnitudes with their degree, which enter into its expression. We may thus easily obtain the dimensions of work:—
Work = f × s = mv2∕2 = ML2T-2.
10 The reason is to be found in the large number of indeterminates in the problem we have to solve. It will be sufficient to enumerate them: the two substances which exist in the anatomical element, protoplasm and reserve-stuff, to which are attributed contrary roles; the two conditions attributable to the protoplasm, of manifested or latent activity; the faculty possessed by both of being prolonged for an indeterminate period, and of encroaching each on its protagonist when its existence is at stake. Here are more elements than are necessary to explain the positive or negative results of all the experiments in the world.
11 There is another reason why the rôle of mechanical energy, compared with that of thermal energy, is reduced, in the partition of afferent, alimentary energy—at least, in animals which have not to do excessive work. The unit of heat, the Calorie, is equivalent to 425 units of work—i.e., to 425 kilogrammetres. In the animal at rest, the number of kilogrammetres representing the different quantities of work done is small, the number of corresponding Calories is 425 times smaller. It becomes almost negligeable in comparison with the considerable number of Calories dissipated in the form of heat.
12 It is not certain, however, that all the precautions taken have the desired result. You cannot entirely deprive meat of its carbohydrates.
13 M. Le Dantec, of whose philosophical and rigorously systematic mind I have the highest opinion, has laid down a new conception of life, the essential basis of which is this very distinction between elementary life and ordinary life; between the life of the elements or of the beings formed from a single cell, protophytes and protozoa, and the life of ordinary animals and plants, which are multicellular complexes, and for that reason called metazoa and metaphytes.
Further, in the elementary life peculiar to monocellular beings (protozoa and cellular elements), M. Le Dantec distinguishes three manners of being:—The first condition, which is elementary life manifested in all its perfection, cellular health; the second condition is deteriorated elementary life, cellular disease; and the third condition, which is latent life. I should say at once that in so far as the fundamental distinction of the phenomena of elementary life and those of the general life of animals and ordinary plants, metazoa or metaphytes is concerned, we find it neither justified nor useful. And further, manifested elementary life, as M. Le Dantec understands it, would only belong to a small number of elementary beings—for the protozoa, starting with the infusoria, are not among the number—and to a still smaller number of anatomical elements, since among the vertebrates we recognize as almost the only elements satisfying it, the ovule, and perhaps the leucocyte. Physiologists, therefore, do not agree with M. Le Dantec as to the utility of adding one condition more to those we all admit—namely, manifested animal life and latent life.
14 Amylolytic ferments change starch and glycogen (amyloses) into sugar.—Tr.
15 Proteolytic ferments change proteids into peptones and proteoses.—Tr.
16 The enzyme known as lipase splits the fat or oil in germinating seeds into a fatty acid and glycerine.—Tr.
17 These ideas are clearly brought to light in a series of articles in the Revue Philosophique, published in 1879 under the title of “La problème physiologique de la vie,” and endorsed by A. Dastre in his commentary on the Phénomènes communs aux animaux et aux plantes.
18 Bear-animalcules, Sloth-animalcules. An order of Arachnida.—Tr.
19 Minute thread worms, known as paste-eels and vinegar-eels.—Tr.
20 Genus of Infusoria. Colpodea cucullus is found in infusions of hay.—Tr.
21 Lately destroyed in a storm. [Tr.]