Читать книгу The Philosophy of Health (Vol. 1&2) - Thoman Southwood Smith - Страница 8

Table of Contents

Relation between the physical condition and happiness, and between happiness and longevity—Longevity a good, and why—Epochs of life—The age of maturity the only one that admits of extension—Proof of this from physiology—Proof from statistics—Explanation of terms—Life a fluctuating quantity—Amount of it possessed in ancient Rome: in modern Europe: at present in England among the mass of the people and among the higher classes.

Life depends on the action of the organic organs. The action of the organic organs depends on certain physical agents. As each organic organ is duly supplied with the physical agent by which it carries on its respective process, and as it duly appropriates what it receives, the perfection of the physical condition is attained; and, according to the perfection or imperfection of the physical condition, supposing no accident interrupt its regular course, is the length or the brevity of life.

It is conceivable that the physical condition might be brought to a high degree of perfection, the mind remaining in a state but little fitted for enjoyment; because it is necessary to enjoyment that there be a certain development, occupation, and direction of the mental powers and affections: and the mental state may be neglected, while attention is paid to the physical processes. But the converse is not possible. The mental energies cannot be fully called forth while the physical condition is neglected. Happiness presupposes a certain degree of excellence in the physical condition; and unless the physical condition be brought to a high degree of excellence, there can be no such development, occupation, and direction of the mental powers and affections as is requisite to a high degree of enjoyment.

That state of the system in which the physical condition is sound is in itself conducive to enjoyment; while a permanent state of enjoyment is in its turn conducive to the soundness of the physical condition. It is impossible to maintain the physical processes in a natural and vigorous condition if the mind be in a state of suffering. The bills of mortality contain no column exhibiting the number of persons who perish annually from bodily disease, produced by mental suffering; but every one must occasionally have seen appalling examples of the fact. Every one must have observed the altered appearance of persons who have sustained calamity. A misfortune, that struck to the heart, happened to a person a year ago; observe him some time afterwards; he is wasted, worn, the miserable shadow of himself; inquire about him at the distance of a few months, he is no more.

It is stated by M. Villermé, that the ordinary rate of mortality in the prisons of France, taking all together, is one in twenty-three—a rate which corresponds to the age of sixty-five in the common course of life. But in the vast majority of cases the unfortunate victims of the law are no older than from twenty-five to forty-five years of age. Taking them at the mean age of thirty-five, it follows that the suffering from imprisonment, and from the causes that lead to it, is equivalent to thirty years wear and tear of life. But this is not all; for it is found that, during imprisonment, the ordinary chances of death are exactly quadrupled.

In regard to the whole population of a country, indigence may be assumed to be a fair measure of unhappiness, and wealth of happiness. If the rate of mortality in the indigent class be compared with that of the wealthy, according to M. Villermé, it will be found in some cases to be just double. Thus it is affirmed that, in some cases in France, taking equal numbers, where there are one hundred deaths in a poor arrondissement, there are only fifty in a rich; and that taking together the whole of the French population, human life is protracted twelve years and a half among the wealthy beyond its duration among the poor: consequently, in the one class, a child, newly born, has a probability of living forty-two and a half years; in the other only thirty years.

In the great life-insurance establishments in England, a vast proportion of the persons who insure their lives are persons compelled to do so by their creditors; while three-fourths of those who voluntarily insure their lives are professional men, living in great towns, and experiencing the anxieties and fatigues, the hopes and disappointments of professional life. In one of these establishments in London, out of 330 deaths that happened in twenty-six years preceding the year 1831, it was found that eleven died by suicide, being one in thirty, implying the existence of an appalling amount of mental suffering. The number of persons belonging to an insurance office who perish by suicide is sure to be accurately known, death by suicide rendering the policy void. It would be most erroneous to suppose that these persons put an end to their existence under the mere influence of the mental states of disappointment and despondency. The mind reacted upon the body: produced physical disease, probably inflammation of the brain, and under the excitement of this physical disease, the acts of suicide were committed. More than one case has come to my knowledge in which inflammation of the brain having been excited by mental suffering, suicide was committed by cutting the throat. During the flow of blood, which was gradual, the brain was relieved; the mind became perfectly rational; and the patient might have been saved had a surgeon been upon the spot, or had the persons about the patient known where and how to apply the pressure of the finger to staunch the flow of blood, until surgical aid could be procured.

By a certain amount and intensity of misery life may be suddenly destroyed; by a smaller amount and intensity, it may be slowly worn out and exhausted. The state of the mind affects the physical condition; but the continuance of life is wholly dependent on the physical condition: it follows that in the degree in which the state of the mind is capable of affecting the physical condition, it is capable of influencing the duration of life.

Were the physical condition always perfect, and the mental state always that of enjoyment, the duration of life would always be extended to the utmost limit compatible with that of the organization of the body. But as this fortunate concurrence seldom or never happens, human life seldom or never numbers the full measure of its days. Uniform experience shows, however, that, provided no accident occur to interrupt the usual course, in proportion as body and mind approximate to this state, life is long; and as they recede from it, it is short. Improvement of the physical condition affords a foundation for the improvement of the mental state; improvement of the mental state improves up to a certain point the physical condition; and in the ratio in which this twofold improvement is effected, the duration of life increases.

Longevity then is a good, in the first place, because it is a sign and a consequence of the possession of a certain amount of enjoyment; and in the second place, because this being the case, of course in proportion as the term of life is extended, the sum of enjoyment must be augmented. And this view of longevity assigns the cause, and shows the reasonableness of that desire for long life which is so universal and constant as to be commonly considered instinctive. Longevity and happiness, if not invariably, are generally, co-incident.

If there may be happiness without longevity, the converse is not possible: there cannot be longevity without happiness. Unless the state of the body be that of tolerable health, and the state of the mind that of tolerable enjoyment, long life is unattainable: these physical and mental conditions no longer existing, nor capable of existing, the desire of life and the power of retaining it cease together.

An advanced term of life and decrepitude are commonly conceived to be synonymous: the extension of life is vulgarly supposed to be the protraction of the period of infirmity and suffering, that period which is characterized by a progressive diminution of the power of sensation, and a consequent and proportionate loss of the power of enjoyment, the "sans teeth, sans eyes, sans taste, sans every thing." But this is so far from being true, that it is not within the compass of human power to protract in any sensible degree the period of old age properly so called, that is, the stage of decrepitude. In this stage of existence, the physical changes that successively take place clog, day by day, the vital machinery, until it can no longer play. In a space of time, fixed within narrow limits, the flame of life must then inevitably expire, for the processes that feed it fail. But though, when fully come, the term of old age cannot be extended, the coming of the term may be postponed. To the preceding stage, an indefinite number of years may be added. And this is a fact of the deepest interest to human nature.

The division of human life into periods or epochs is not an arbitrary distinction, but is founded on constitutional differences in the system, dependent on different physiological conditions. The periods of infancy, childhood, boyhood, adolescence, manhood, and old age, are distinguished from each other by external characters, which are but the outward signs of internal states. In physiological condition, the infant differs from the child, the child from the boy, the boy from the man, and the adult from the old man, as much in physical strength as in mental power. There is an appointed order in which these several states succeed each other; there is a fixed time at which one passes into another. That order cannot be inverted: no considerable anticipation or postponement of that fixed time can be effected. In all places and under all circumstances, at a given time, though not precisely at the same time in all climates and under all modes of life, infancy passes into childhood, childhood into boyhood, boyhood into adolescence, and adolescence into manhood. In the space of two years from its birth, every infant has ceased to be an infant, and has become a child; in the space of six years from this period, every male child will have become a boy; add eight years to this time, and every boy will have become a young man; in eight years more, every young man will have become an adult man; and in the subsequent ten years, every adult man will have acquired his highest state of physical perfection. But at what period will this state of physical perfection decline? What is the maximum time during which it can retain its full vigour? Is that maximum fixed? Is there a certain number of years in which, by an inevitable law, every adult man necessarily becomes an old man? Is precisely the same number of years appointed for this transition to every human being? Can no care add to that number? Can no imprudence take from it? Does the physiological condition or the constitutional age of any two individuals ever advance to precisely the same point in precisely the same number of years? Physically and mentally, are not some persons older at fifty than others are at seventy? And do not instances occasionally occur in which an old man, who reaches even his hundredth year, retains as great a degree of juvenility as the majority of those who attain to eighty?

If this be so, what follows? One of the most interesting consequences that can be presented to the human mind. The duration of the periods of infancy, childhood, boyhood, and adolescence, is fixed by a determinate number of years. Nothing can stay, nothing retard, the succession of each. Alike incapable of any material protraction is the period of old age. It follows that every year by which the term of human existence is extended is really added to the period of mature age; the period when the organs of the body have attained their full growth and put forth their full strength; when the physical organization has acquired its utmost perfection; when the senses, the feelings, the emotions, the passions, the affections, are in the highest degree acute, intense, and varied; when the intellectual faculties, completely unfolded and developed, carry on their operations with the greatest vigour, soundness, and continuity; in a word, when the individual is capable of receiving and of communicating the largest amount of the highest kind of enjoyment.

A consideration more full of encouragement, more animating, there cannot be. The extension of human life, in whatever mode and degree it may be possible to extend it, is the protraction of that portion of it, and only of that portion of it, in which the human being is capable of RECEIVING AND OF COMMUNICATING THE LARGEST MEASURE OF THE NOBLEST KIND OF ENJOYMENT.

Considerations, purely physiological, establish this indubitably; but it is curious that a class of facts, totally different from those of a physiological nature, equally prove it; namely, the results obtained from the observation of the actual numbers that die at different ages, and the knowledge consequently acquired of the progressive decrement of life. Mortality is subject to a law, the operation of which is as regular as that of gravitation. The labours of my valued friend Mr. Finlaison, the actuary of the National Debt, have not only determined what that law is in relation to different nations at different periods of their history, but this celebrated calculator has also invented a striking mode of expressing and representing the fact. He constructed a chart on which 100 perpendicular lines, answering to the respective ages of human life, are laid down and numbered in succession. These are crossed at right angles by 500 horizontal lines; so that, in the manner of musical notation, a point may be laid down either on the horizontal line, or on the space between any two of them: and thus, 1000 points may be laid down on each of the perpendicular lines. The horizontal lines are in like manner numbered from 1 to 1000, ascending from the base. Taking any observation which shows the number of living persons that commence, and in like manner the number that die in each particular year of human life, the calculator reduced by the rule of three every such actual number of living persons for every separate year to 10,000: he next showed the corresponding proportion of deaths out of such 10,000. These proportions he represented on the chart by a point inserted on the horizontal line or space for the number of deaths, and on the perpendicular line for the particular age. He then connected all the points so laid down, and the result is a curve, representing the track of death through an equal number of human beings existing at each age of life. As the curve rises on the perpendicular line, at any given age, it indicates by so much an increase of the mortality at that age; and as the curve falls, the reverse is denoted.

Now, it is a highly interesting fact, that the curves on this chart drawn upon it before the physiological phenomena were known to the operator, placed there because such he found to be the actual path along which death marshals his course, exactly correspond to the epochs which physiology teaches to be determinate stages of human existence. The infant, the child, the boy, the adolescent, the man, the old man, are not exposed to the same danger. The liability of each to death is not merely different; it is widely different; the liability of each class is uniformly the same, the circumstances influencing life remaining the same; and under no known change of circumstances does the relative liability of the class vary; under no change does the liability of the adolescent become that of the infant, or the liability of the adult that of the aged. Take from any statistical document any number of persons; observe out of this number the proportion that dies at the different stages just enumerated; and the period of human life which admits of extension will be strikingly manifest. Take with this view the Prussian statistical tables, the general correctness of which is admitted. From these tables it appears, and the correctness of the result is confirmed by a multitude of other tables, that out of a million living male births, there will die in the first year of life 180,492 infants, and out of the like number of living female births, there will die 154,705 infants. Let us follow up the decrement of life through the different epochs of human existence, confining our observations to the male sex, in which the development is more emphatically marked.

In Mr. Finlaison's report, printed by the House of Commons on the 30th of March, 1829, there are six original observations on the mortality of as many separate sets of annuitants of the male sex.

From an examination and comparison of these observations, it appears—1st. That the rate of mortality falls to a minimum at the close of the period of childhood. 2d. That from this point the mortality rises until the termination of adolescence or the commencement of adult age. 3d. That from the commencement of adult age the mortality again declines, and continues to decline to the period of perfect maturity. And 4th. That from the period of perfect maturity, the mortality rises, and uniformly, without a single exception, returns, at the age of forty-eight, to the point at which it stood at the termination of adolescence. These results clearly indicate that certain fixed periods are marked by nature as epochs of human life; and that at the date of the recorded facts which furnish the data for these observations, and as far as regards the class of persons to which they relate, the age of forty-eight was the exact point at which the meridian of life was just passed, and a new epoch began. The following table exhibits at one view the exact results of each of the observations. For example,

According to the observation No.	The mortality is at a minimum at the age of	From whence it rises until the age of	From this point it declines to the age of	And from this age it again rises but is not equal to mortality in the 2d column until the age of
15	13	23	34	48
16	13	23	35	48
17	14	22	33	48
18	13	23	33	48
19	13	24	34	48
20	13	24	34	48

The observation, No. 15, is founded on the large mass of 9,347 lives and 4,870 deaths. From this observation, it appears that, at the age of thirteen, the mortality out of a million is 5,742, being 174,750 less than in the first year of infancy At the age of twenty-three, it is 15,074, being 9,332 more than at the close of childhood. At the age of thirty-four, the period of complete manhood, it falls to 11,707, being 3,367 less than at the close of adolescence. At the age of forty-eight, the mortality returns to 14,870, all but identically the same as at twenty-three, the adult age. From the age of forty-eight, when, as has been stated, life just begins to decline from its meridian, the mortality advances slowly, but in a steady and regular progression. Thus, at the age of fifty-eight it is 29,185, being 14,315 more than at the preceding decade, or almost exactly double. At the age of sixty-eight, it is 61,741, being 32,556 more than at the preceding decade, or more than double. At the age of seventy-eight, it is 114,255, being 52,514 more than at the preceding decade. At the age of eighty-eight, it is 246,803, being 132,548 more than at the preceding decade.

During the first year of infancy, as has been shown, the mortality out of a million is 180,492. At the extreme age of eighty-four, it is 178,130, very nearly the same as in the first year of infancy. Greatly as the mortality of all the other epochs of life is affected by country, by station, by a multitude of influences arising out of these and similar circumstances; yet the concurrent evidence of all observation shows that at this and the like advanced ages the mean term of existence is nearly the same in all countries, at all periods, and among all classes of society. Thus, among the nobility and gentry of England, the expectation of life at eighty-four is four years; among the poor fishermen of Ostend, it is precisely the same. M. De Parcieux, who wrote just ninety years ago, establishes the expectation of life at that time in France, at the same age, to have been three and a half years; and Halley, who wrote 120 years ago, and whose observations are derived from documents which go back to the end of the seventeenth century, states the expectation of life at eighty-four to be two years and nine months.

From these statements, then, it is obvious, that from the termination of infancy at three years of age, a decade of years brings childhood to a close, during which the mortality, steadily decreasing, comes to its minimum. Another decade terminates the period of adolescence, during which the mortality as steadily advances. A third decade changes the young adult into a perfect man, and during this period, the golden decade of human life, the mortality again diminishes; while, during another decade and a half, the mortality slowly rises, and returns at the close of the period to the precise point at which it stood at adult age. Thus the interval between the period of birth and that of adult age includes a term of twenty-three years. The interval between the period of adult age and that when life just begins to decline from its meridian, includes a term of twenty-four years: consequently, a period more than equal to all the other epochs of life from birth to adult age is enjoyed, during which mortality makes no advance whatever. Now the term of years included in the several epochs that intervene between birth and adult age is rigidly fixed. Thus the period of infancy includes precisely three years, that of childhood ten years, and that of adolescence ten years. Within the space of time comprehended in these intervals, physiological changes take place, on which depend every thing that is peculiar to the epochs. These changes cannot be anticipated, cannot be retarded, except in a very slight degree. In all countries, among all classes, they take place in the same order and nearly in the same space of time. In like manner, in extreme old age, or the age of decrepitude, which may be safely assumed to commence at the period when the mortality equals that of the first year of infancy, namely, the age of eighty-four, physiological changes take place, which, within a given space of time, inevitably bring life to a close. That space of time, in all countries, in all ranks, in all ages, or rather as far back as any records enable us to trace the facts, appears to be the same. As within a given time the boy must ripen into manhood, so within a given time the man of extreme old age must be the victim of death. Consequently, it is the interval between the adult age and the age of decrepitude, and only this, that is capable of extension. During the interval between adult age and the perfect meridian of life, comprehending at present, as we have seen, a period of twenty-four years, the constitution remains stationary, mortality making no sensible inroad upon it. But there is no known reason why this stationary or mature period of life should, like the determinate epochs, be limited to a fixed term of years. On the contrary, we do in fact know that it is not fixed; for we know that the physiological changes on which age depends are, in some cases, greatly anticipated, and in others, proportionately postponed; so that some persons are younger at sixty, and even at seventy, than others are at fifty; whereas, an analogous anticipation or postponement of the other epochs of life is never witnessed. So complete is the proof, that the extension of human life can consist in the protraction neither of the period of juvenility, nor in that of senility, but only in that of maturity.

Were it necessary to adduce further evidence of this most interesting fact, it would be found equally in the statistics of disease as in those of mortality. Indeed, the evidence derived from both these sources must be analogous, because mortality is invariably proportionate to the causes of mortality, of which causes, sickness, in all its forms, may be taken as the general or collective expression.

We do not possess the same means of illustrating the prevalence of disease through all the epochs of life as we do of showing the intensity of mortality; yet the report of Mr. Finlaison, already referred to, enables us to show its comparative prevalence at several of those stages. Thus, from this document, it appears, that among the industrious poor of London, members of benefit societies, out of a million of males, the proportion constantly sick at the age of twenty-three, is 19,410; at the age of twenty-eight, it is 19,670; at the age of thirty-three, it is 19,400; at the age of thirty-eight, it is 23,870; at the age of forty-three, it is 26,260; at the age of forty-eight, it is 26,140; at the age of fifty-three, it is 27,060; at the age of fifty-eight, it is 36,980; at the age of sixty-three, it is 57,000; at the age of sixty-eight, it is 108,040; at the age of seventy-three and upwards, it is 317,230. The prevalence of sickness is not an exact and invariable measure of the intensity of mortality; but there is a close connexion between them, as is manifest from the progressively increasing amount of sickness, as age advances. Thus, in the first ten years from the age of twenty-three to that of thirty-three, there is no increase of sickness, its prevalence is all but identically the same; in the next ten years from the age of thirty-three to that of forty-three, the increase of sickness, as compared with that of the preceding decade, is 6,860; in the next ten years from the age of forty-three to that of fifty-three, the increase is only 800; in the next ten years from the age of fifty-three to that of sixty-three, the increase is 29,940, while from the age of sixty-three to seventy-three, it is 260,230.

Such are the results derived from the experience of disease considered in the aggregate, all its varied forms taken together. I am enabled further to present an exact and most instructive proof, that one particular disease which, in this point of view, may be considered as more important than any other, because it is the grand agent of death, namely fever, carries on its ravages in a ratio which steadily and uniformly increases as the age of its victim advances. Having submitted the experience of the London Fever Hospital for the ten years preceding January 1834, an observation including nearly 6,000 patients affected with this malady, to Mr. Finlaison, it was subjected by him to calculation. Among other curious and instructive results to be stated hereafter, it was found that the mortality of fever resolves itself into the following remarkable progression. Thus suppose 100,000 patients to be attacked with this disease between the ages of 5 and 16, of these there would die - 8,266 and of an equal number

between	15 and 26	there would die	11,494
	25 and 36	"""	17,071
	35 and 46	"""	21,960
	45 and 56	"""	30,493
	55 and 66	"""	40,708
	65 and upwards	"""	44,643

Thus the risk of life from this malady is twice as great at the age of thirty-one as it is at eleven. It is also nearly twice as great at forty-one as it is at twenty-one. It is five times as great at sixty-one as it is at eleven, and nearly four times as great above sixty-five as it is at twenty-one.

From the whole of the foregoing statements, it is manifest that life is a fluctuating quantity. In order to compare this fluctuating quantity under different circumstances, writers on this branch of statistics use several terms, the exact meaning of which it is desirable to explain. It is, for example, very important to have a clear understanding of what is meant by such expressions as the following: the expectation, the probability, the value, the decrement of life, and the law of mortality.

1. The Expectation of Life. It is important to bear in mind that several expressions in common use have a signification perfectly synonymous with this: namely, share of existence; mean duration of life; la vie moyenne.

By these terms is expressed the total number of years, including also the fractional parts of a year, ordinarily attained by human beings from and after any given age. Suppose, for example, that one thousand persons enter on the eighty-sixth year of their age: suppose the number of years and days which each one of them lives afterwards be observed and recorded; suppose the number ultimately attained by each be formed into a sum total; suppose this total be divided equally among the thousand, the quotient of this division is said to be each one's share of existence, or his mean duration of life, or his expectation of life. Thus, of the thousand persons in the present case supposed to commence the age of eighty-five, suppose the number of years they collectively attain amount to 3,500 years: the one-thousandth part of 3,500 is three and a half: three years and a half then is said to be the expectation of life at the age of eighty-five, because, of all the persons originally starting, this is the equal share of existence that falls to the lot of each.

2. Probability of Life; or the probable duration of life, la vie probable. These are synonymous terms, in use chiefly among continental writers as an expression of the comparative duration of life. The tabular methods of setting forth the duration of life consist, for the most part, in assuming that 10,000 infants are born; and that at the age of one, two, three, and each successive year of life, there are so many still remaining in existence. Fix on any age; observe what number remain alive to commence that age; note at what age this number decreases to one-half; the age at which they so come to one-half is called the probable term of life; because, say the continental writers, it is an equal wager whether a person shall or shall not be alive at that period. Thus, suppose one thousand males commence together the age of eighty-four; suppose the table indicate that there will be alive at the age of eighty-five, 817; at the age of eighty-six, 648; at the age of eighty-seven, 493; at the age of eighty-eight, 357, and so on. In the present case, the probable duration of life at eighty-four is said to be very nearly three years, because, at the age of eighty-seven there are left alive 493, very nearly one-half of the thousand that originally started together.

3. Value of Life. This term, when used accurately, expresses the duration of life as measured by one or other of the methods already expounded. But it is sometimes popularly used in a loose and singularly inaccurate sense. Thus it is very commonly said—"Such a man's life is not worth ten years' purchase," which is the same thing as to say, that an annuity, suppose a hundred pounds a year, payable during the life of the person in question, is not worth ten times its magnitude, that is one thousand pounds. If a thousand pounds be put into a bank at some rate of interest to be agreed upon, and if a hundred pounds be drawn every year from the stock, the expression under consideration affirms that the person in question will be dead before the principal and interest are exhausted. For instance, at four per cent., the value of an annuity of one hundred pounds to a man of the age of twenty-five is 1694l., which is 16-9/10 years' purchase; whereas, his expectation of life at that age is 35-9/10 years.

4. Law of Mortality. By this term is expressed the proportion out of any determinate number of human beings who enter on a given year of age, that will die in that year. Every observation on the duration of life presents certain numbers, which, by recorded facts, are found to pass through each year of age, and also shows how many have died or failed to pass through every year of age. Those numbers, by the rule of three, are converted into the proportions who would die at each age out of one million of persons, if such a number had commenced it. Suppose, then, a million of persons to be in existence at the first year of age; suppose a million to be in existence at the second year of age; suppose a million to be in existence at the third year of age; and in this manner suppose an equal number to be in existence at the commencement of each and every year to the extreme term of human life. Now, the proportions that by actual observation are found to die at each and every year out of the million that were alive at the commencement of it, form separately the law of mortality for each year, and collectively for the whole of life.

5. Decrement of Life. Assuming, as before, that a million of male children are born alive (for the still-born must be excluded from the calculation) if it be found that 180,492 would die in the first year, it follows that the difference, namely, 819,508, will enter upon the age of one year. Suppose the law of mortality indicate that the proportion that will die, out of a million, between the age of one and two, is 30,000; it is plain that the number who would die out of 819,508 will by the rule of three be 27,863, and consequently that the residue, namely, 791,615, will remain alive, and so enter on the age of two years. This method being pursued through each and every age to the extreme term of life, when none of the original million survive, the result is a table of mortality in the form in which it is commonly presented in the works of writers on this branch of science. In the table thus constructed there is a column containing the number of living persons who, out of the original million, lived to enter upon each and every year. Of this rank of numbers the difference between each term and its next succeeding one, is the number who die in that particular interval: that number is the measure of what is technically called the decrement of life for that particular year, and the whole of the decrements for each and every year taken collectively is termed the decrement of life. The decrement of life, then, is not only not the same as the law of mortality, but is carefully to be distinguished from it. The law of mortality is derived from observing the number who die out of one and the same number which is always supposed to enter on each and every year. The decrement of life constitutes a rank of numbers arising out of the successive deaths; that is, out of the original million in the first year; out of the survivors of that million in the second year; out of the survivors of those survivors in the third year, and so on. In the first case the number of the living is always the same; the number that die is the variable quantity: in the second case the number of the living is the variable quantity, while the number that die may remain pretty much the same for a succession of years; and on casting the eye on the tables constructed in the ordinary mode, it will be seen that the number often does remain the same for a considerable series of years.

We have said that life is a fluctuating quantity. It fluctuates in different countries at the same period; in the same country at different periods; in the same country, at the same period, in different places; in the same country, at the same period, in the same place, among different classes; in the same country, at the same period, in the same place, among the same class, at the different determinate stages of life. Some few of these fluctuations, and more especially the last, depend on the primary constitution of the organization in which life itself has its seat, over which man has little or no control. The greater part of them depend on external and adventitious agencies over which man has complete control. Human ignorance, apathy, and indolence, may render the duration of life, in regard to large classes and entire countries, short; human knowledge, energy and perseverance, may extend the duration of life far beyond what is commonly imagined. It will be interesting and instructive to select a few of the more striking examples of this from the records we possess, few and imperfect as they are, in relation to this subject.

Of the duration of life in the earlier periods of the history of the human race we know nothing with exactness, though there are incidental statements which afford the means of deducing with some probability the rate of mortality in particular situations. There has come down to us one document through Domitius Ulpianus, a judge, who flourished in the reign of Alexander Severus, which enables us to form a probable conjecture at least of the opinion of the Roman people of the value of life among the citizens of Rome in that age. It happened at Rome as in other countries, that when an estate came into the possession of an individual it was burthened with a provision for another person during the life of the latter, a younger brother, for example. This provision was called by the Romans an aliment. No estate, burthened with such a provision, could be sold by the heir in possession, unless the purchaser retained in his hands so much of the price as was deemed adequate to secure the regular and continuous payment of the aliment. This imposed upon the Romans the necessity of considering what the term of life would probably be from and after any given age. What they did conceive that term to be is stated in a document of Ulpianus, recorded by Justinian, and given in the note below.1 This document imports that from infancy up to the age of

	20,	there should be allowed	30	years
From	20 to 25	"" ""	28	"
	25 to 30	"" ""	25	"
	30 to 35	"" ""	22	"
	35 to 40	"" ""	20	"
	————
From	50 to 55	"" ""	9	"
	55 to 60	"" ""	7	"
And at all ages	above 60	"" ""	5	"

But between 40 and 50, as many years were to be allowed as the age of the party fell short of 60, deducting one year.

No clue has hitherto been obtained to the discovery of the real meaning of this document. It is, however, highly probable that the Romans had fallen on one of the two methods of measuring the value of life already explained; namely, that termed the Probability of Life. Of the two modes of determining the value of life, the probability was more likely to occur to a Roman judge than the expectation. He had no tables, no registers to guide him. What course, then, would he be likely to take? Probably he would form a list of his own school-fellows and others within his own knowledge, of the age, say, of twenty. By prevailing on persons of his own age, on whose correctness he could rely, to draw out similar lists, he might accumulate some thousand names. In this list it is probable that the male sex alone would be included, on account of the greater ease of ascertaining both their exact age and the exact date of their death. For the same reason, it is probable that the list would consist only of the nobility and the inhabitants of towns. Having thus completed his list, the next step would be to frame another list of all who died at the age of twenty-one; and next, another list of all who died at the age of twenty-two, and so on through each and every year of life. Now by subtracting the number in the list, No. 1, that is, those who died between twenty and twenty-one, from the number who originally started at twenty, which, in other words, would be to find the decrement of life, in the mode already explained, he would see how many lived to commence the age of twenty-one, and so on, through each year of life. But this would be to construct a table, showing the probable duration of life; that is, a table from which he could observe at what advanced age the number originally starting at twenty, and so on, came to diminish to one-half, when it would naturally occur to him that it is an equal wager whether such younger life would or would not be in existence at the advanced age so ascertained. If we suppose this to have been the method actually adopted by the Roman judge, and apply it to the table of Ulpianus, the result obtained is consistent in an extraordinary degree, and is highly interesting.

There is reason to believe that the mortality at present throughout Europe, taking all countries together, including towns and villages, and combining all classes into one aggregate, is one in thirty-six. Süssmilch, a celebrated German writer, who flourished about the middle of the last century, estimated it at this average at that period. The result of all Mr. Finlaison's investigations is a conviction that the average for the whole of Europe does not materially differ at the present time. He has ascertained by an actual observation, that in the year 1832 it was precisely this in the town of Ostend. Taking this town, then, as the subject of comparison, it is found that the probable duration of life among the male sex at Ostend exceeds the Roman allowance by the following number of years; namely,

At the age of 17, the excess in round

	numbers is	5	years.
22	""	5
27	""	5
32	""	5
37	""	3
42	""	3
47	""	5
52	""	5
57	""	4
62	""	4
67	""	2
72	""	1
77	""	0