III.—The Use of Lactic Acid
The general measures of hygiene directed against infectious diseases play a part in prolonging the lives of old people; but, in addition to the microbes which invade the body from outside, there is a rich source of harm in microbes which inhabit the body. The most important of these belong to the intestinal flora which is abundant and varied. Now the attempt to destroy the intestinal microbes by the use of chemical agents has little chance of success, and the intestine itself may be harmed more than the microbes. If, however, we observe the new-born child we find that, when suckled by its mother, its intestinal microbes are very different and much fewer than if it be fed with cows' milk. I am strongly convinced that it is advantageous to protect ourselves by cooking all kinds of food which, like cows' milk, are exposed to the air. It is well-known that other means—as, for instance, the use of lactic acid—will prevent food outside the body from going bad. Now as lactic fermentation serves so well to arrest putrefaction in general, why should it not be used for the same purpose within the digestive tube? It has been clearly proved that the microbes which produce lactic acid can, and do, control the growth of other microbes within the body, and that the lactic microbe is so much at home in the human body that it is to be found there several weeks after it has been swallowed.
From time immemorial human beings have absorbed quantities of lactic microbes by consuming in the uncooked condition substances such as soured milk, kephir, sauerkraut, or salted cucumbers, which have undergone lactic fermentation. By these means they have unknowingly lessened the evil consequences of intestinal putrefaction. The fact that so many races make soured milk and use it copiously is an excellent testimony to its usefulness, and critical inquiry shows that longevity, with few traces of senility, is conspicuous amongst peoples who use sour milk extensively.
A reader who has little knowledge of such matters may be surprised by my recommendation to absorb large quantities of microbes, as the general belief is that microbes are all harmful. This belief, however, is erroneous. There are many useful microbes, amongst which the lactic bacilli have an honourable place. If it be true that our precocious and unhappy old age is due to poisoning of the tissues, the greater part of the poison coming from the large intestine, inhabited by numberless microbes, it is clear that agents which arrest intestinal putrefaction must at the same time postpone and ameliorate old age. This theoretical view is confirmed by the collection of facts regarding races which live chiefly on soured milk, and amongst which great ages are common.
IV.—An Ideal Old Age
As I have shown in the "Nature of Man," the human constitution as it exists to-day, being the result of a long evolution and containing a large animal element, cannot furnish the basis of rational morality. The conception which has come down from antiquity to modern times, of a harmonious activity of all the organs, is no longer appropriate to mankind. Organs which are in course of atrophy must not be re-awakened, and many natural characters which, perhaps, were useful in the case of animals, must be made to disappear in men.
Human nature which, like the constitutions of other organisms, is subject to evolution, must be modified according to a definite ideal. Just as a gardener or stock-raiser is not content with the existing nature of the plants and animals with which he is occupied, but modifies them to suit his purposes, so also the scientific philosopher must not think of existing human nature as immutable, but must try to modify it for the advantage of mankind. As bread is the chief article in the human food, attempts to improve cereals have been made for a very long time, but in order to obtain results much knowledge is necessary. To modify the nature of plants, it is necessary to understand them well, and it is necessary to have an ideal to be aimed at. In the case of mankind the ideal of human nature, towards which we ought to press, may be formed. In my opinion this ideal is "orthobiosis"—that is to say, the development of human life, so that it passes through a long period of old age in active and vigorous health, leading to a final period in which there shall be present a sense of satiety of life, and a wish for death.
Just as we must study the nature of plants before trying to realise our ideal, so also varied and profound knowledge is the first requisite for the ideal of moral conduct. It is necessary not only to know the structure and functions of the human organism, but to have exact ideas on human life as it is in society. Scientific knowledge is so indispensable for moral conduct that ignorance must be placed among the most immoral acts. A mother who rears her child in defiance of good hygiene, from want of knowledge, is acting immorally towards her offspring, notwithstanding her feeling of sympathy. And this also is true of a government which remains in ignorance of the laws which regulate human life and human society.
If the human race come to adopt the principles of orthobiosis, a considerable change in the qualities of men of different ages will follow. Old age will be postponed so much that men of from sixty to seventy years of age will retain their vigour, and will not require to ask assistance in the fashion now necessary. On the other hand, young men of twenty-one years of age will no longer be thought mature or ready to fulfil functions so difficult as taking a share in public affairs. The view which I set forth in the "Nature of Man" regarding the danger which comes from the present interference of young men in political affairs has since then been confirmed in the most striking fashion.
It is easily intelligible that in the new conditions such modern idols as universal suffrage, public opinion, and the referendum, in which the ignorant masses are called on to decide questions which demand varied and profound knowledge, will last no longer than the old idols. The progress of human knowledge will bring about the replacement of such institutions by others, in which applied morality will be controlled by the really competent persons. I permit myself to suppose that in these times scientific training will be much more general than it is just now, and that it will occupy the place which it deserves in education and in life.