moment in course of dissipation, is from moment to moment renewed from without: the rises and falls in the supply, being balanced by rises and falls in the expenditure; as witness the correspondence between the magnetic variations and the cycle of the solar spots. But the fact it chiefly concerns us to observe, is, that this process must go on bringing things ever nearer to complete rest. These mechanical movements, meteorologic and geologic, which are continually being equilibrated, both temporarily by counter-movements and permanently by the dissipation of such movements and counter-movements, will slowly diminish as the quantity of force received from the Sun diminishes. As the insensible motions propagated to us from the centre of our system become feebler, the sensible motions here produced by them must decrease; and at that remote period when the solar heat has ceased to be appreciable, there will no longer be any appreciable re-distributions of matter on the surface of our planet.
Thus from the highest point of view, all terrestrial changes are incidents in the course of cosmical equilibration. It was before pointed out, (§ 80) that of the incessant alterations which the Earth’s crust and atmosphere undergo, those which are not due to the still-progressing motion of the Earth’s substance towards its centre of gravity, are due to the still-progressing motion of the Sun’s substance towards its centre of gravity. Here it is to be remarked, that this continuance of integration in the Earth and in the Sun, is a continuance of that transformation of sensible motion into insensible motion which we have seen ends in equilibration; and that the arrival in each case at the extreme of integration, is the arrival at a state in which no more sensible motion remains to be transformed into insensible motion—a state in which the forces producing integration and the forces opposing integration, have become equal.
* * * * * § 133. Every living body exhibits, in a four-fold form, the process we are tracing out—exhibits it from moment to moment in the balancing of mechanical forces; from hour to hour in the balancing of functions; from year to year in the changes of state that compensate changes of condition; and finally in the complete arrest of vital movements at death. Let us consider the facts under these heads.
The sensible motion constituting each visible action of an organism, is soon brought to a close by some adverse force within or without the organism. When the arm is raised, the motion given to it is antagonized partly by gravity and partly by the internal resistances consequent on structure; and its motion, thus suffering continual deduction, ends when the arm has reached a position at which the forces are equilibrated. The limits of each systole and diastole of the heart, severally show us a momentary equilibrium between muscular strains that produce opposite movements; and each gush of blood requires to be immediately followed by another, because the rapid dissipation of its momentum would otherwise soon bring the mass of circulating fluid to a stand. As much in the actions and re-actions going on among the internal organs, as in the mechanical balancing of the whole body, there is at every instant a progressive equilibration of the motions at every instant produced. Viewed in their aggregate, and as forming a series, the organic functions constitute a dependent moving equilibrium—a moving equilibrium, of which the motive power is ever being dissipated through the special equilibrations just exemplified, and is ever being renewed by the taking in of additional motive power. Food is a store of force which continually adds to the momentum of the vital actions, as much as is continually deducted from them by the forces overcome. All the functional movements thus maintained, are, as we have seen, rhythmical (§ 96); by their union compound rhythms of various lengths and complexities are produced; and in these simple and compound rhythms, the process of equilibration, besides being exemplified at each extreme of every rhythm, is seen in the habitual preservation of a constant mean, and in the re-establishment of that mean when accidental causes have produced divergence from it. When, for instance, there is a great expenditure of motion through muscular activity, there arises a re-active demand on those stores of latent motion which are laid up in the form of consumable matter throughout the tissues: increased respiration and increased rapidity of circulation, are instrumental to an extra genesis of force, that counter-balances the extra dissipation of force. This unusual transformation of molecular motion into sensible motion, is presently followed by an unusual absorption of food—the source of molecular motion; and in proportion as there has been a prolonged draft upon the spare capital of the system, is there a tendency to a prolonged rest, during which that spare capital is replaced. If the deviation from the ordinary course of the functions has been so great as to derange them, as when violent exertion produces loss of appetite and loss of sleep, an equilibration is still eventually effected. Providing the disturbance is not such as to overturn the balance of the functions, and destroy life (in which case a complete equilibration is suddenly effected), the ordinary balance is by and by re-established: the returning appetite is keen in proportion as the waste has been large; while sleep, sound and prolonged, makes up for previous wakefulness. Not even in those extreme cases where some excess has wrought a derangement that is never wholly rectified, is there an exception to the general law; for in such cases the cycle of the functions is, after a time, equilibrated about a new mean state, which thenceforth becomes the normal state of the individual. Thus, among the involved rhythmical changes constituting organic life, any disturbing force that works an excess of change in some direction, is gradually diminished and finally neutralized by antagonistic forces; which thereupon work a compensating change in the opposite direction, and so, after more or less of oscillation, restore the medium condition. And this process it is, which constitutes what physicians call the _vis medicatrix naturæ_. The third form of equilibration displayed by organic bodies, is a necessary sequence of that just illustrated. When through a change of habit or circumstance, an organism is permanently subject to some new influence, or different amount of an old influence, there arises, after more or less disturbance of the organic rhythms, a balancing of them around the new average condition produced by this additional influence. As temporary divergences of the organic rhythms are counteracted by temporary divergences of a reverse kind; so there is an equilibration of their permanent divergences by the genesis of opposing divergences that are equally permanent. If the quantity of motion to be habitually generated by a muscle, becomes greater than before, its nutrition becomes greater than before. If the expenditure of the muscle bears to its nutrition, a greater ratio than expenditure bears to nutrition in other parts of the system; the excess of nutrition becomes such that the muscle grows. And the cessation of its growth is the establishment of a balance between the daily waste and the daily repair—the daily expenditure of force, and the amount of latent force daily added. The like must manifestly be the case with all organic modifications consequent on change of climate or food. This is a conclusion which we may safely draw without knowing the special re-arrangements that effect the equilibration. If we see that a different mode of life is followed, after a period of functional derangement, by some altered condition of the system—if we see that this altered condition, becoming by and by established, continues without further change; we have no alternative but to say, that the new forces brought to bear on the system, have been compensated by the opposing forces they have evoked. And this is the interpretation of the process which we call _adaptation_. Finally, each organism illustrates the law in the _ensemble_ of its life. At the outset it daily absorbs under the form of food, an amount of force greater than it daily expends; and the surplus is daily equilibrated by growth. As maturity is approached, this surplus diminishes; and in the perfect organism, the day’s absorption of potential motion balances the day’s expenditure of actual motion. That is to say, during adult life, there is continuously exhibited an equilibration of the third order. Eventually, the daily loss, beginning to out-balance the daily gain, there results a diminishing amount of functional action; the organic rhythms extend less and less widely on each side of the medium state; and there finally results that complete equilibration which we call death.
The ultimate structural state accompanying that ultimate functional state towards which an organism tends, both individually and as a species, may be deduced from one of the propositions set down in the opening section of this chapter. We saw that the limit of heterogeneity is arrived at whenever the equilibration of any aggregate becomes complete—that the re-distribution of matter can continue so long only as there continues any motion unbalanced. Whence we found it to follow that the final structural arrangements, must be such as will meet all the forces acting on the aggregate, by equivalent antagonist forces. What is the implication in the case of organic aggregates; the equilibrium of which is a moving one? We have seen that the maintenance of such a moving equilibrium, requires the habitual genesis of internal forces corresponding in number, directions, and amounts to the external incident forces—as many inner functions, single or combined, as there are single or combined outer actions to be met. But functions are the correlatives of organs; amounts of functions are, other things equal, the correlatives of sizes of organs; and combinations of functions the correlatives of connections of organs. Hence the structural complexity accompanying functional equilibration, is definable as one in which there are as many specialized parts as are capable, separately and jointly, of counteracting the separate and joint forces amid which the organism exists. And this is the limit of organic heterogeneity; to which man has approached more nearly than any other creature.
Groups of organisms display this universal tendency towards a balance very obviously. In § 96, every species of plant and animal was shown to be perpetually undergoing a rhythmical variation in number—now from abundance of food and absence of enemies rising above its average; and then by a consequent scarcity of food and abundance of enemies being depressed below its average. And here we have to observe that there is thus maintained an equilibrium between the sum of those forces which result in the increase of each race, and the sum of those forces which result in its decrease. Either limit of variation is a point at which the one set of forces, before in excess of the other, is counterbalanced by it. And amid these oscillations produced by their conflict, lies that average number of the species at which its expansive tendency is in equilibrium with surrounding repressive tendencies. Nor can it be questioned that this balancing of the preservative and destructive forces which we see going on in every race, must necessarily go on. Since increase of number cannot but continue until increase of mortality stops it; and decrease of number cannot but continue until it is either arrested by fertility or extinguishes the race entirely.
* * * * * * * * * * § 134. The equilibrations of those nervous actions which constitute what we know as mental life, may be classified in like manner with those which constitute what we distinguish as bodily life. We may deal with them in the same order.
Each pulse of nervous force from moment to moment generated, (and it was shown in § 97 that nervous currents are not continuous but rhythmical) is met by counteracting forces; in overcoming which it is dispersed and equilibrated. When tracing out the correlation and equivalence of forces, we saw that each sensation and emotion, or rather such part of it as remains after the excitation of associated ideas and feelings, is expended in working bodily changes—contractions of the involuntary muscles, the voluntary muscles, or both; as also in a certain stimulation of secreting organs. That the movements thus initiated are ever being brought to a close by the opposing forces they evoke, was pointed out above; and here it is to be observed that the like holds with the nervous changes thus initiated. Various facts prove that the arousing of a thought or feeling, always involves the overcoming of a certain resistance: instance the fact that where the association of mental states has not been frequent, a sensible effort is needed to call up the one after the other; instance the fact that during nervous prostration there is a comparative inability to think—the ideas will not follow one another with the habitual rapidity; instance the converse fact that at times of unusual energy, natural or artificial, the friction of thought becomes relatively small, and more numerous, more remote, or more difficult connections of ideas are formed. That is to say, the wave of nervous energy each instant generated, propagates itself throughout body and brain, along those channels which the conditions at the instant render lines of least resistance; and spreading widely in proportion to its amount, ends only when it is equilibrated by the resistances it everywhere meets. If we contemplate mental actions us extending over hours and days, we discover equilibrations analogous to those hourly and daily established among the bodily functions. In the one case as in the other, there are rhythms which exhibit a balancing of opposing forces at each extreme, and the maintenance of a certain general balance. This is seen in the daily alternation of mental activity and mental rest—the forces expended during the one being compensated by the forces acquired during the other. It is also seen in the recurring rise and fall of each desire: each desire reaching a certain intensity, is equilibrated either by expenditure of the force it embodies, in the desired actions, or, less completely, in the imagination of such actions: the process ending in that satiety, or that comparative quiescence, forming the opposite limit of the rhythm. And it is further manifest under a two-fold form, on occasions of intense joy or grief: each paroxysm of passion, expressing itself in vehement bodily actions, presently reaches an extreme whence the counteracting forces produce a return to a condition of moderate excitement; and the successive paroxysms finally diminishing in intensity, end in a mental equilibrium either like that before existing, or partially differing from it in its medium state. But the species of mental equilibration to be more especially noted, is that shown in the establishment of a correspondence between relations among our states of consciousness and relations in the external world. Each outer connection of phenomena which we are capable of perceiving, generates, through accumulated experiences, an inner connection of mental states; and the result towards which this process tends, is the formation of a mental connection having a relative strength that answers to the relative constancy of the physical connection represented. In conformity with the general law that motion pursues the line of least resistance, and that, other things equal, a line once taken by motion is made a line that will be more readily pursued by future motion; we have seen that the ease with which nervous impressions follow one another, is, other things equal, great in proportion to the number of times they have been repeated together in experience. Hence, corresponding to such an invariable relation as that between the resistance of an object and some extension possessed by it, there arises an indissoluble connection in consciousness; and this connection, being as absolute internally as the answering one is externally, undergoes no further change—the inner relation is in perfect equilibrium with the outer relation. Conversely, it hence happens that to such uncertain relations of phenomena as that between clouds and rain, there arise relations of ideas of a like uncertainty; and if, under given aspects of the sky, the tendencies to infer fair or foul weather, correspond to the frequencies with which fair or foul weather follow such aspects, the accumulation of experiences has balanced the mental sequences and the physical sequences. When it is remembered that between these extremes there are countless orders of external connections having different degrees of constancy, and that during the evolution of intelligence there arise answering internal associations having different degrees of cohesion; it will be seen that there is a progress towards equilibrium between the relations of thought and the relations of things. This equilibration can end only when each relation of things has generated in us a relation of thought, such that on the occurrence of the conditions, the relation in thought arises as certainly as the relation in things. Supposing this state to be reached (which however it can be only in infinite time) experience will cease to produce any further mental evolution—there will have been reached a perfect correspondence between ideas and facts; and the intellectual adaptation of man to his circumstances will be complete. The like general truths are exhibited in the process moral of adaptation; which is a continual approach to equilibrium between the emotions and the kinds of conduct necessitated by surrounding conditions. The connections of feelings and actions, are determined in the same way as the connections of ideas: just as repeating the association of two ideas, facilitates the excitement of the one by the other; so does each discharge of feeling into action, render the subsequent discharge of such feeling into such action more easy. Hence it happens that if an individual is placed permanently in conditions which demand more action of a special kind than has before been requisite, or than is natural to him—if the pressure of the painful feelings which these conditions entail when disregarded, impels him to perform this action to a greater extent—if by every more frequent or more lengthened performance of it under such pressure, the resistance is somewhat diminished; then, clearly, there is an advance towards a balance between the demand for this kind of action and the supply of it. Either in himself, or in his descendants continuing to live under these conditions, enforced repetition must eventually bring about a state in which this mode of directing the energies will be no more repugnant than the various other modes previously natural to the race. Hence the limit towards which emotional modification perpetually tends, and to which it must approach indefinitely near (though it can absolutely reach it only in infinite time) is a combination of desires that correspond to all the different orders of activity which the circumstances of life call for—desires severally proportionate in strength to the needs for these orders of activity; and severally satisfied by these orders of activity. In what we distinguish as acquired habits, and in the moral differences of races and nations produced by habits that are maintained through successive generations, we have countless illustrations of this progressive adaptation; which can cease only with the establishment of a complete equilibrium between constitution and conditions.
Possibly some will fail to see how the equilibrations described in this section, can be classed with those preceding them; and will be inclined to say that what are here set down as facts, are but analogies. Nevertheless such equilibrations are as truly physical as the rest. To show this fully, would require a more detailed analysis than can now be entered on. For the present it must suffice to point out, as before (§ 82), that what we know subjectively as states of consciousness, are, objectively, modes of force; that so much feeling is the correlate of so much motion; that the performance of any bodily action is the transformation of a certain amount of feeling into its equivalent amount of motion; that this bodily action is met by forces which it is expended in overcoming; and that the necessity for the frequent repetition of this action, implies the frequent recurrence of forces to be so overcome. Hence the existence in any individual of an emotional stimulus that is in equilibrium with certain external requirements, is literally the habitual production of a certain specialized portion of nervous energy, equivalent in amount to a certain order of external resistances that are habitually met. And thus the ultimate state, forming the limit towards which Evolution carries us, is one in which the kinds and quantities of mental energy daily generated and transformed into motions, are equivalent to, or in equilibrium with, the various orders and degrees of surrounding forces which antagonize such motions.
* * * * * § 135. Each society taken as a whole, displays the process of equilibration in the continuous adjustment of its population to its means of subsistence. A tribe of men living on wild animals and fruits, is manifestly, like every tribe of inferior creatures, always oscillating about that average number which the locality can support. Though by artificial production, and by successive improvements in artificial production, a superior race continually alters the limit which external conditions put to population; yet there is ever a checking of population at the temporary limit reached. It is true that where the limit is being so rapidly changed as among ourselves, there is no actual stoppage: there is only a rhythmical variation in the rate of increase. But in noting the causes of this rhythmical variation—in watching how, during periods of abundance, the proportion of marriages increases, and how it decreases during periods of scarcity; it will be seen that the expansive force produces unusual advance whenever the repressive force diminishes, and _vice versâ_; and thus there is as near a balancing of the two as the changing conditions permit.
The internal actions constituting social functions, exemplify the general principle no less clearly. Supply and demand are continually being adjusted throughout all industrial processes; and this equilibration is interpretable in the same way as preceding ones. The production and distribution of a commodity, is the expression of a certain aggregate of forces causing special kinds and amounts of motion. The price of this commodity, is the measure of a certain other aggregate of forces expended by the labourer who purchases it, in other kinds and amounts of motion. And the variations of price represent a rhythmical balancing of these forces. Every rise or fall in the rate of interest, or change in the value of a particular security, implies a conflict of forces in which some, becoming temporarily predominant, cause a movement that is presently arrested or equilibrated by the increase of opposing forces; and amid these daily and hourly oscillations, lies a more slowly-varying medium, into which the value ever tends to settle; and would settle but for the constant addition of new influences. As in the individual organism so in the social organism, functional equilibrations generate structural equilibrations. When on the workers in any trade there comes an increased demand, and when in return for the increased supply, there is given to them an amount of other commodities larger than was before habitual—when, consequently, the resistances overcome by them in sustaining life are less than the resistances overcome by other workers; there results a flow of other workers into this trade. This flow continues until the extra demand is met, and the wages so far fall again, that the total resistance overcome in obtaining a given amount of produce, is as great in this newly-adopted occupation as in the occupations whence it drew recruits. The occurrence of motion along lines of least resistance, was before shown to necessitate the growth of population in those places where the labour required for self-maintenance is the smallest; and here we further see that those engaged in any such advantageous locality, or advantageous business, must multiply till there arises an approximate balance between this locality or business and others accessible to the same citizens. In determining the career of every youth, we see an estimation by parents of the respective advantages offered by all that are available, and a choice of the one which promises best; and through the consequent influx into trades that are at the time most profitable, and the withholding of recruits from over-stocked trades, there is insured a general equipoise between the power of each social organ and the function it has to perform.
The various industrial actions and re-actions thus continually alternating, constitute a dependent moving equilibrium like that which is maintained among the functions of an individual organism. And this dependent moving equilibrium parallels those already contemplated, in its tendency to become more complete. During early stages of social evolution, while yet the resources of the locality inhabited are unexplored, and the arts of production undeveloped, there is never anything more than a temporary and partial balancing of such actions, under the form of acceleration or retardation of growth. But when a society approaches the maturity of that type on which it is organized, the various industrial activities settle down into a comparatively constant state. Moreover, it is observable that advance in organization, as well as advance in growth, is conducive to a better equilibrium of industrial functions. While the diffusion of mercantile information is slow, and the means of transport deficient, the adjustment of supply to demand is extremely imperfect: great over-production of each commodity followed by great under-production, constitute a rhythm having extremes that depart very widely from the mean state in which demand and supply are equilibrated. But when good roads are made, and there is a rapid diffusion of printed or written intelligence, and still more when railways and telegraphs come into existence—when the periodical fairs of early days lapse into weekly markets, and these into daily markets; there is gradually produced a better balance of production and consumption. Extra demand is much more quickly followed by augmented supply; and the rapid oscillations of price within narrow limits on either side of a comparatively uniform mean, indicate a near approach to equilibrium. Evidently this industrial progress has for its limit, that which Mr. Mill has called “the stationary state.” When population shall have become dense over all habitable parts of the globe; when the resources of every region have been fully explored; and when the productive arts admit of no further improvements; there must result an almost complete balance, both between the fertility and mortality of each society, and between its producing and consuming activities. Each society will exhibit only minor deviations from its average number, and the rhythm of its industrial functions will go on from day to day and year to year with comparatively insignificant perturbations. This limit, however, though we are inevitably advancing towards it, is indefinitely remote; and can never indeed be absolutely reached. The peopling of the Earth up to the point supposed, cannot take place by simple spreading. In the future, as in the past, the process will be carried on rhythmically, by waves of emigration from new and higher centres of civilization successively arising; and by the supplanting of inferior races by the superior races they beget; and the process so carried on must be extremely slow. Nor does it seem to me that such an equilibration will, as Mr. Mill suggests, leave scope for further mental culture and moral progress; but rather that the approximation to it must be simultaneous with the approximation to complete equilibrium between man’s nature and the conditions of his existence.
One other kind of social equilibration has still to be considered:—that which results in the establishment of governmental institutions, and which becomes complete as these institutions fall into harmony with the desires of the people. There is a demand and supply in political affairs as in industrial affairs; and in the one case as in the other, the antagonist forces produce a rhythm which, at first extreme in its oscillations, slowly settles down into a moving equilibrium of comparative regularity. Those aggressive impulses inherited from the pre-social state—those tendencies to seek self-satisfaction regardless of injury to other beings, which are essential to a predatory life, constitute an anti-social force, tending ever to cause conflict and eventual separation of citizens. Contrariwise, those desires whose ends can be achieved only by union, as well as those sentiments which find satisfaction through intercourse with fellow-men, and those resulting in what we call loyalty, are forces tending to keep the units of a society together. On the one hand, there is in each citizen, more or less of resistance against all restraints imposed on his actions by other citizens: a resistance which, tending continually to widen each individual’s sphere of action, and reciprocally to limit the spheres of action of other individuals, constitutes a repulsive force mutually exercised by the members of a social aggregate. On the other hand, the general sympathy of man for man, and the more special sympathy of each variety of man for others of the same variety, together with sundry allied feelings which the social state gratifies, act as an attractive force, tending ever to keep united those who have a common ancestry. And since the resistances to be overcome in satisfying the totality of their desires when living separately, are greater than the resistances to be overcome in satisfying the totality of their desires when living together, there is a residuary force that prevents their separation. Like all other opposing forces, those exerted by citizens on each other, are ever producing alternating movements, which, at first extreme, undergo a gradual diminution on the way to ultimate equilibrium. In small, undeveloped societies, marked rhythms result from these conflicting tendencies. A tribe whose members have held together for a generation or two, reaches a size at which it will not hold together; and on the occurrence of some event causing unusual antagonism among its members, divides. Each primitive nation, depending largely for its continued union on the character of its chief, exhibits wide