Equally interesting is that law of our nature which determines growth by exercise. It is a fact clearly demonstrated by modern science that the governing organ of the human body, the brain, has distinct portions of its structure devoted to the service of distinct faculties of the mind. Thus the intellectual, the emotional, and the locomotive powers work through corresponding portions of the highly organized brain. Each faculty grows by exercise. Not only does the mental faculty become stronger by use, but its physical organ of expression in the brain, with its dependencies in the rest of the body, become larger and stronger with a richer supply of blood and greater aptitude for instantaneous action. This condition of the physical organ reacts upon the mind, which takes greater pleasure in acting in a certain direction when it finds the brain so keenly responsive to its impulses. If the proper distribution of force is disturbed in any individual by the neglect to exercise important portions of our nature, an antagonism of faculties springs up, one part growing at the expense of another part. Thus the emotional may destroy the intellectual life in an individual who is subjected to undue excitement of the passions, particularly if the type of the nature is not largely emotional. The other faculties will rapidly lose their power. The intellect suffers, judgment is lost, and mental confusion produced, which is really a species of insanity. Those organs of the body, also, which are most intimately connected with the excited portion of the brain become involved, and their functions may be entirely deranged. The automatic power of the human body may also assume undue control in those who yield to fancies and caprice, and lead an unnatural and sedentary life. There is an antagonism between this automatic force and the life of relation or brain-life of the individual. The more the balance of powers is lost in the human brain—reason being no longer the controlling force—the greater becomes the power of this instinctive life of the body, the greater its capability of answering every fanciful suggestion, and even of exciting those suggestions. The individual may thus become the sport of his own unbalanced faculties, and a prey to every species of morbid hallucination.
An organization so complicated (as this human body), designed for such manifold uses, and at the same time drawing the elements of its existence from the external world, must be powerfully influenced by all the circumstances which surround it. Certain physical and mental conditions are essential to human growth, to health. Hence the question of food and clothing, of drainage and ventilation, of human habitations, of exercise and occupations, attain equal importance and dignity, as essential to the fulfilment of the great changeless plan of life.
Thus we are brought face to face with a great fixed fact, a fact which concerns every human being during every moment of life—viz., God’s unchanging law of human growth. This law we are called on to study, to obey, and obedience to it is placed first in the order of human duties. Obedience can only be rendered by study of the objects of physical life, of its structure, its conditions, its rules. Its learning, thus regarded, becomes sacred learning, and ignorance is criminal.
The folly and wickedness of our practical contempt for the great laws of human growth may be measured by the penalties of suffering, illness, and premature death attached to this neglect. This is rendered more striking by observing, first of all, the great force of the principle of vitality, the strong tendency to live and resist injurious influences, which we all possess. Nothing is more remarkable in the history of the human race than its great power of adaptability. Scattered all over the surface of the globe, under the most varying conditions, men still live and thrive. The cities of Cuença and Quito, at a height of 9,600 feet above the level of the sea, possess large and flourishing populations; so also do the cities of Holland and New Orleans, which lie below its level. Multitudes of workmen live in the galleries of the deepest mines, many hundred feet below the surface of the earth, deprived of light, breathing air much more condensed, living under a much stronger pressure than that of the ordinary atmosphere. And, on the other hand, scientific observers have taken up their residence for a long period on the crest of Pichincha, at an elevation of 14,826 feet. Agassiz spent some weeks in investigations on the Jung-Frau. Gay Lussac attained the highest elevation ever reached by man in his balloon, 28,000 feet. All can recall the thrilling narratives of Arctic voyagers, where the thermometer has been known to measure 91° below zero. Contrast this with the burning sun of India, where 120° Fahrenheit is observed; where glass is cracked by the heat. A wide range of more than 200° of temperature, and yet the heat of the human body maintains its steady and necessary amount, never materially varying under the two extremes. Similiar illustrations of the power of human nature to adapt itself to unnatural conditions might be drawn from all the other elements necessary to life.
Notwithstanding this remarkable power of vitality, which can brave such extreme variations in physical conditions and endure enormous privations, careful observation all over our country presents a fearful record of death, sickness, and physical degeneration produced by our own social arrangements—arrangements and habits so destructive to the human organization that they overpower even this great capability of adaptation.
This is seen in the statistics of our towns, in the condition of our peasant population, in our social and domestic experience.
The statistics of all our large towns demonstrate the great and unnatural destruction of life that takes place in these centres of civilization, where the highest medical skill is found, and placed freely at the call of poor as well as rich. The natural death-rate at present is 17 per thousand—i.e., that under the most favourable conditions as amongst the upper classes in our healthiest cities, in the healthiest country districts, 17 out of every thousand persons die each year all the world over, a lower mortality being exceptional; but the following was the death-rate of our chief cities (1868) instead of the natural rate of 17 per thousand: Bristol, 23; London and Birmingham, 24; Dublin, 25; Edinburgh, 27; Liverpool, 29; Glasgow, 30; Manchester, 32. That means that in London alone, in a year of no special sickness, more than 21,000 were killed who ought to have lived. In the British Islands an army of over 176,516 lives were swept off unnecessarily. This is not all: a much larger proportion of the population is always ill at one time; about 78,000 in London is reckoned, of whom one-third are suffering from preventable diseases. This calculation does not take into account those feeble, ailing persons who are never more than half well, who lack strength and energy for the daily fulfilment of duty. It is shown that in the whole of England the people have only a mean life-time of forty-one years—not half the term of life that seems to belong naturally to our race. Of those who died within the year, over 134,000 were in ripe manhood; but yet more noteworthy are the deaths under the age of twenty-five: over 242,000 perished in childhood and youth. The wholesale slaughter of children in our civilized country is truly appalling. Out of 233,515 deaths at all ages, 94,804, or 40·60 per cent., were those of children under five years of age.
To understand fully the grave import of these records three facts must be noted: first, that the death-rate of a country is always under-stated; second, that town populations increase at a much more rapid ratio than country populations; third, that the death-rate increases in direct proportion to the density of the population.
In proof of these three propositions let me quote from recent testimony of our most eminent statisticians:
‘Wherever the population is increasing the amount of mortality is under-rated in consequence of there being an excess of young people in those numbers, which make the mortality appear lower than it really is. The mortality of London appears much less by statistics than it actually is; it is reduced in two ways by having a large influx of persons at the period of age when mortality is low, and by the departure and return of patients to the country to die, as consumptives for instance. The causes of disease in London are excessively active, as is seen, for instance, in the mortality of male children under five years of age, which is about 8 per cent. (i.e., 80 per 1,000), while in some of the more healthy districts it is not more than 4 per cent.’ Again: ‘Of the 20,066,224 persons enumerated in England in 1861, nearly 11,000,000 were in the towns and 9,000,000 in villages and country around the towns. The total population in London and 71 of the largest towns in England was over 7,667,622, and the population in the country and in smaller towns was over 12,398,602, so that there are nearly eight-twentieths of the population in those 72 towns. The total increase from 1801 to 1861 in the population of England was over 11,173,688, and one-half of that increase was in those 72 towns. It will thus be apparent that the town population is increasing at a much more rapid rate than the country population.’ ‘The country population now is very nearly the same as it was in 1801. By a law, which at present is quite constant, the mortality increases rapidly with the density of the population. In our thinnest districts the mortality is about 15 per 1,000; in our densest districts it ranges from 28 to 33. This relation is a constant law: where there are 179 persons to a square mile, there the mortality is from 17 to 19; where the density of population varies from 3,000 upwards, the mortality ranges from 26 to 33; so that under our present arrangements there is a constant connection between the density of population and its mortality. That connection is not necessary; our towns might be made nearly as healthy as these country districts, having a mortality of 17 to 20.’ Of the circumstances under which large masses of our population grow up, another distinguished physician writes: ‘They create special diseases, demoralize the population, and in course of generations completely overthrow the physique of the people. It is impossible to walk through the central streets (of this large town) without observing that you are in contact with a population awfully degraded, both in its physical and moral attributes; a population whose mere external characteristics impress you at once with the idea of a depth of degradation of bad habits growing for generations, in consequence of these arrangements.’ ‘Thousands and hundreds of thousands are thus brought up.’