Chapter 22   Equilibration

§170. towards what do these changes tend? Will they go on for ever? or will there be an end to them? Can things increase in heterogeneity through all future time? or must there be a degree which the differentiation and integration of Matter and Motion cannot pass? Is it possible for this universal metamorphosis to proceed in the same general course indefinitely? or does it work towards some ultimate state admitting no further modification of like kind? The last of these alternative conclusions is that to which we are inevitably driven. Whether we watch concrete processes, or whether we consider the question in the abstract, we are alike taught that Evolution has an impassable limit.

The re-distributions of matter which go on around us, are ever being brought to conclusions by the dissipation of the motions which effect them. The rolling stone parts with portions of its momentum to the things it strikes, and finally comes to rest; as do also, in like manner, the various things it has struck. Descending from the clouds and trickling over the Earth's surface till it gathers into brooks and rivers, water, still running towards a lower level, is at last arrested by the resistance of other water that has reached the lowest level. In the lake or sea thus formed, every agitation raised by a wind or the immersion of a solid body, propagates itself around in waves which diminish as they widen, and gradually become lost to observation in motions communicated to the atmosphere and the matter on the shores. The impulse given by a player to a harp-string is transformed through its vibrations into aerial pulses; and these, spreading on all sides, and weakening as they spread, soon cease to be perceptible, and are gradually expended in generating thermal undulations that radiate into space: each aerial pulse causing compression and evolution of heat. Equally in the cinder which falls out of the fire, and in the vast mass of molten lava ejected by a volcano, we see that the molecular agitation disperses itself by radiation; so that the temperature inevitably sinks at last to the same degree as that of surrounding bodies. The proximate rationale of the process exhibited under these several forms, lies in the fact dwelt on when treating of the Multiplication of Effects, that motions are ever being decomposed into divergent motions, and these into re-divergent motions. The rolling stone sends off the stones it hits in directions differing more or less from its own, and they do the like with the things they hit. Move water or air, and the movement is quickly resolved into dispersed movements. The heat produced by pressure in a given direction diffuses itself by undulations in all directions. That is to say, these motions undergo division and subdivision, and by continuance of this process without limit they are, though never lost, gradually dissipated.

In all cases, then, there is a progress toward equilibrium. That universal co-existence of antagonist forces which, as we before saw, necessitates the universality of rhythm, and which, as we before saw, necessitates the decomposition of every force into divergent forces, at the same time necessitates the ultimate establishment of a balance. Every motion, being motion under resistance, is continually suffering deductions; and these unceasing deductions finally result in the cessation of the motion.

The general truth thus frustrated under its simplest aspect, we must now look at under those more complex aspects it usually presents throughout Nature. In nearly all cases, the motion of an aggregate is compound; and the equilibration of each of its components, being carried on independently, does not affect the rest. The ship's bell that has ceased to vibrate, still continues those vertical and lateral oscillations caused by the ocean-swell. The water of a smooth stream on whose surface have died away the undulations caused by a rising fish, moves as fast as before towards the sea. The arrested bullet travels with undiminished speed round the Earth's axis. And were the rotation of the Earth destroyed, there would not be implied any diminution of the Earth's movement with respect to the Sun and other external bodies. So that in every case, what we regard as equilibration is a disappearance of some one or more of the many movements a body possesses, while its other movements continue as before. That this process may be duly realized and the state of things towards which it tends fully understood, it will be well here to cite a case in which we may watch this successive equilibration of combined movements more completely than we can do in those above instanced. Our end will best be served not by the most imposing but by the most familiar example. Let us take that of a spinning top. When the string which has been wrapped round a top's axis is violently drawn off, and the top falls on to the table, it usually happens that besides the rapid rotation two other movements are given to it. A slight horizontal momentum, unavoidably impressed on it when leaving the handle, carries it. away bodily from the place on which it drops; and in consequence of its axis being more or less inclined, it falls into a certain oscillation, described by the expressive though inelegant word "wabbling." These two subordinate motions, variable in their proportions to each other and to the chief motion, are commonly soon brought to a close by separate processes of equilibrium. The momentum which carries the top bodily along the table, resisted somewhat by the air but mainly by the irregularities of the surface, shortly disappears; and the top thereafter continues to spin on one spot. Meanwhile, in consequence of that opposition which the axial momentum of a rotating body makes to any change in the plane of rotation, (so beautifully exhibited by the gyroscope,) the "wabbling" diminishes, and like the other is quickly ended. These minor motions having been dissipated, the rotatory motion, interfered with only by atmospheric resistance and the friction of the pivot, continues some time with such uniformity that the top appears stationary: there being thus temporary established a condition which the French mathematicians have termed equilibrium mobile. It is true that when the velocity of rotation sinks below a certain point, new motions commence and increase till the top falls; but these are merely incidental to a case in which the centre of gravity is above the point of support. Were the top, having an axis of steel, to be suspended from a surface adequately magnetized, the moving equilibrium would continue until the top became motionless, without any further change of attitude. Now the facts which it behoves us here to observe are these. First, that the various motions which an aggregate possesses are separately equilibrated: those which are smallest, or which meet with the greatest resistance, or both, disappearing first; and leaving at last that which is greatest, or meets with least resistance, or both. Second, that when the aggregate has a movement of its parts with respect to each other which encounters but little external resistance, there is apt to be established a moving equilibrium. Third, that this moving equilibrium eventually lapses into complete equilibrium.

Fully to comprehend the process of equilibration, is not easy; since we have simultaneously to contemplate various phases of it. The best course will be to glance separately at what we may conveniently regard as its four different orders. The first order includes the comparatively simple motions, as those of projectiles, which are not prolonged enough to exhibit their rhythmical character, but which, being quickly divided and subdivided into motions communicated to other portions of matter, are presently dissipated in the rhythm of ethereal undulations. In the second order, comprehending various kinds of ordinary vibration or oscillation, the implied energy is used up in generating a tension which, having become equal to it or momentarily equilibrated with it, thereupon produces a motion in the opposite direction, that is subsequently equilibrated in like manner: thus causing a visible rhythm which is presently lost in invisible rhythms. The third order of equilibration, not hitherto noticed, obtains in those aggregates which continually receive as much energy as they expend. The steam-engine (and especially that kind which feeds its own furnace and boiler) supplies an example. Here the energy from moment to moment dissipated in overcoming the resistance of the machinery driven, is from moment to moment re-placed from the fuel; and the balance of the two is maintained by a raising or lowering of the expenditure according to the variation of the supply: each increase or decrease in the quantity of steam, resulting in a rise or fall of the engine's movement, such as brings it to a balance with the increased or decreased resistance. This, which we may fitly call the dependent moving equilibrium, should be specify noted; since it is one that we shall commonly meet with throughout various phases of Evolution. The equilibrium to be distinguished as of the fourth order, is the independent or perfect moving equilibrium. This we see illustrated in the rhythmical motions of the Solar System, which, being resisted only by a medium of inappreciable density, undergo no sensible diminution in such periods of time as we can measure.

Something has still to be added. The reader must note two leading truths brought out by the foregoing exposition: the one concerning the ultimate, or rather the penultimate, state of motion which the processes described tend to bring about; the other concerning the concomitant distribution of matter. This penultimate state of motion is the moving equilibrium, which tends to arise in an aggregate having compound motions, as a transitional state on the way towards complete equilibrium. Throughout Evolution of all kinds there is a continual approximation to, and more or less complete maintenance of, this moving equilibrium. As in the Solar System there has been established an independent moving equilibrium -- an equilibrium such that the relative motions of its members are continually so counterbalanced by opposite motions, that the mean state of the aggregate never varies; so is it, though in a less distinct manner, with each form of dependent moving equilibrium. The state of things exhibited in the cycles of terrestrial changes, in the balanced functions of organic bodies that have reached their adult forms, and in the acting and re-acting processes of fully-developed societies, is similarly one characterized by compensating oscillations. The involved combination of rhythms seen in each of these cases, has an average condition which remains practically constant during the deviations ever taking place on opposite sides of it. And the fact which we have here to observe is that, as a corollary from the general law of equilibrium, every evolving aggregate must go on changing until a moving equilibrium is established; since, as we have seen, an excess of force which the aggregate possesses in any direction, must eventually be expended in overcoming resistances to change in that direction: leaving behind only those movements which compensate one another, and so form a moving equilibrium. Respecting the structural state simultaneously reached, it must obviously be one presenting an arrangement of forces that counterbalance all the forces to which the aggregate is subject. So long as there remains a residual force in any direction -- be it excess of a force exercised by the aggregate on its environment, or of a force exercised by its environment on the aggregate, equilibrium does not exist; and therefore the re-distribution of matter must continue. Whence it follows that the limit of heterogeneity towards which every aggregate progresses, is the formation of as many specializations and combinations of parts, as there are specialized and combined forces to be met.

§171. Those successively changed forms which, if the nebular hypothesis be granted, must have arisen during the evolution of the Solar System, were so many transitional kinds of moving equilibrium, severally giving place to more enduring kinds. Thus the assumption of an oblate spheroidal figure by condensing nebulous matter, was the assumption of a temporary and partial moving equilibrium among the component parts -- a moving equilibrium that must have grown more settled as local conflicting movements were dissipated. In the formation and detachment of the nebulous rings which, according to this hypothesis, from time to time took place, we have instances of progressive equilibration severally ending in the establishment of a complete moving equilibrium. For the genesis of each such ring implies a balancing of that attractive force which the whole spheroid exercises on its equatorial portion, by that centrifugal force which the equatorial portion has acquired during previous concentration. So long as these two forces are not equal, the equatorial portion follows the contracting mass; but as soon as the second force has increased up to an equality with the first, the equatorial portion can follow no further and remains behind. While, however, the resulting ring, regarded as a whole, has reached a state of moving equilibrium, its parts are not balanced with respect to one another. As we before saw (§150) the probabilities against the maintenance of an annular form by nebulous matter are great: from the instability of the homogeneous, it is inferable that nebulous matter so distributed will break up into portions, and eventually concentrate into a single mass. That is to say, the ring will progress towards a moving equilibrium of a more complete kind, during the dissipation of that motion which maintained its particles in a diffused form; leaving at length a planetary body attended perhaps by a group of minor bodies similarly produced, constituting a moving equilibrium that is all but perfect.*
<* Sir David Brewster has cited with approval, a calculation by M. Babinet, to the effect that on the hypothesis of nebular genesis, the matter of the Sun, when it filled the Earth's orbit, must have taken 3181 years to rotate; and that therefore the hypothesis cannot be true. This calculation of M. Babinet may pair-off with that of M. Comte who, contrariwise, made the time of this rotation agree very nearly with the Earth's period of revolution round the Sun. For if M. Comte's calculation involved a petitio principii, that of M. Babinet is based on two assumptions both of which are gratuitous, and one of them inconsistent with the doctrine to be tested. He has evidently proceeded on the current supposition respecting the Sun's internal density, which is not proved, and from which there are reasons for dissenting; and he has evidently taken for granted that all parts of the nebulous spheroid, when it filled the Earth's orbit, has the same angular velocity; whereas if (as is implied in the nebular hypothesis, rationally understood) this spheroid resulted from the concentration of widely-diffused matter, the angular velocity of its equatorial portion would obviously be far greater than that of its central portion.>

Hypothesis aside, the principle of equilibration is still perpetually illustrated in those minor changes of state which the Solar System undergoes. Each planet, satellite, and comet, exhibits at its aphelion a momentary equilibrium between that force which urges it further away from its primary, and that force which retards its retreat. In like manner at perihelion a converse equilibrium is momentarily established. The variation of each orbit in eccentricity, and in the position of its plane, has similarly a limit at which the forces producing change in the one direction, are equalled by those antagonizing it; and an opposite limit at which an opposite arrest takes place. Meanwhile, each of these simple perturbations, as well as each of the complex ones resulting from their combination, exhibits, besides the temporary equilibration at each of its extremes, a certain general equilibration of compensating deviations on either side of a mean state. That the moving equilibrium thus constituted tends, in the course of indefinite time, to lapse into a complete equilibrium, by the gradual decrease of planetary motions and eventual integration of all the separate masses composing the Solar System, is a belief suggested by certain observed cometary retardations -- a belief entertained by some of high authority. The received option that the appreciable diminution in the period of Encke's comet, implies a loss of momentum caused by resistance to the ethereal medium, commits astronomers who hold it, to the conclusion that this same resistance must cause a loss of planetary motions -- a loss which, infinitesimal though it may be in such periods as we can measure, will, if indefinitely continued, bring these motions to a close. Even should there be, as Sir John Herschel suggests, a rotation of the ethereal medium in the same direction with the planets, this arrest, though immensely postponed, would not be absolutely prevented. Such an eventuality, however, must in any case be so inconceivably remote as to have no other than a speculative interest for us. It is referred to here, simply as illustrating the still-continued tendency towards complete equilibrium, through the still-continued dissipation of sensible motion, or transformation of it into insensible motion.

But there is another species of equilibration going on in the Solar System, with which the human race is less remotely concerned. The tacit assumption that the Sun can continue to give off an undiminished amount of light and heat through all future time, is now abandoned. Involving as it does, under a disguise, the conception of power produced out of nothing, it is of the same order as the belief which misleads perpetual-motion schemers. The spreading recognition of the truth that whatever force is manifested under one shape must previously have existed under another shape, implies recognition of the truth that the force known to us in solar radiations, is the changed form of some other force of which the Sun is the seat; and that, by the emission of these radiations, this other force is being slowly exhausted. The force by which the Sun's substance is drawn to his centre of gravity, is the only one which physical laws warrant us in concluding to be the correlate of the forces emanating from him: the only assignable source for the insensible motions constituting solar light and heat, is the sensible motion which disappears during the concentration of the Sun's mass. We before saw it to be a corollary from the nebular hypothesis, that there is such a progressing concentration of the Sun's mass. And here remains to be added the further corollary, that just as in the case of the small members of the Solar System, the heat generated by concentration, once escaping rapidly, has in each left a central residue which escapes but slowly; so in the case of that immensely larger mass forming the Sun, the immensely greater quantity of heat generated and still in process of rapid diffusion, must, as the concentration approaches its limit, diminish in amount, and eventually leave but a relatively small internal remnant. With or without the accompaniment of that hypothesis of nebular condensation whence it naturally follows, the doctrine that the Sun is gradually losing his heat, has now gained general acceptance; and calculations have been made, both respecting the amount of heat and light already radiated, as compared with the amount that remains, and respecting the period during which active radiation will continue. Prof. Helmholtz estimates that since the time when, according to the nebular hypothesis, the matter composing the Solar System extended to the Orbit of Neptune, there has been evolved by the arrest of sensible motion, an amount of heat 454 times as great as that which the Sun still has to give out. He also makes an approximate estimate of the rate at which this remaining 1/464th is being diffused: showing that decrease of the Sun's diameter to the extent of 1/10,000 would produce heat, at the present rate, for more than 2000 years; or in other words, that a contraction of 1/20,000,000 of his diameter, suffices to generate the light and heat annually emitted; and that thus at the present rate of expenditure, the Sun's diameter will diminish by something like 1/20 in the lapse of the next million years.*<* See paper "On the Inter-action of Natural Forces," by Prof. Helmholtz, translated by Prof. Tyndall, and published in the Philosophical Magazine, supplement to Vol. XI, in the fourth series.> Of course these conclusions are but rude approximations to the truth. Until quite recently, we have been totally ignorant of the Sun's chemical composition, and even now have obtained but a superficial knowledge of it. We know nothing of his internal structure; and it is quite possible that the assumptions respecting central density, made in the foregoing estimates, are wrong.

But no uncertainty in the data on which these calculations proceed, and no consequent error in the inferred rate at which the Sun is expending his reserve energy, militates against the general proposition that this reserve of energy is being expended, and must in time be exhausted.

Thus while the Solar System, if evolved from diffused matter, has illustrated the law of equilibration in the establishment of a moving equilibrium; and while, as at present constituted, it illustrates the law of equilibration in the perpetual balancing of all its movements; it also illustrates this law in these processes which astronomers and physicists infer are still going on. That motion of masses produced during Evolution, is being slowly rediffused in molecular motion of the ethereal medium; both through the progressive integration of each mass, and the resistance to its motion through space. Infinitely remote as may be the state when all the relative motions of its masses shall be transformed into molecular motion, and all the molecular motion dissipated; yet such a state of complete integration and complete equilibration, is that towards which the changes now going on throughout the Solar System inevitably tend.

§172. A spherical figure is the one which can alone equilibrate the forces of mutually-gravitating molecules. If an aggregate of such molecules rotates, the form of equilibrium becomes a spheroid of greater or less oblateness, according to the rate of rotation; and it has been ascertained that the Earth is an oblate spheroid, diverging just as much from sphericity as is requisite to counterbalance the centrifugal force consequent on its velocity round its axis. That is to say, during the evolution of the Earth, there has been reached an equilibrium of those forces which affect its general outline. The only other equilibration which the Earth as a whole can exhibit, is the loss of its rotation; and that any such loss is going on we have no direct evidence. It has been contended, however, by Prof. Helmholtz and others, that inappreciable as may be its effect within known periods of time, the friction of the tidal wave must be diminishing the Earth's motion round its axis, and must eventually destroy it. Now though it seems an oversight to say that the axial motion can thus be destroyed, since the extreme effect, to be reached only in infinite time, would be an extension of the Earth's day to the length of lunation; yet it seems clear that this friction of the tidal wave is a real cause of decreasing rotation. Slow as its action is, we must recognize its retarding effect as exemplifying, under another form, the universal progress towards equilibrium.(*)<fn* While the effect of tidal friction is to decrease the rate of rotation, the still-continued contraction of the Earth has the effect of increasing it. How. the difference between these conflicting effects is to be ascertained it is not easy to see.>

It is needless to show in detail how those movements which the Sun's rays generate in the air and water on the Earth's surface, and through them in the Earth's solid substance,(*) <fn* Until I recently consulted his Outlines of Astronomy on another question, I was not aware that so far back as 1833, Sir John Herschel had pointed out that "the sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth." He expressly includes geologic, meteorologic, and vital actions; as also those which we produce by the combustion of coal.> one and all teach the same general truth. Evidently the winds and waves and streams, as well as the denudations and depositions they effect, illustrate on a grand scale, and in endless modes, that gradual dissipation of motions described in the first section, and the consequent tendency towards a balanced distribution of forces. Each of these sensible motions, produced directly or indirectly by integration of those insensible motions communicated from the Sun, becomes divided and subdivided into motions less and less sensible; until by gradual or sudden arrest of each, and production of its equivalent in molecular motion, there is an escape of it into space in the shape of thermal undulations. In their totality, these complex motions constitute a dependent moving equilibrium. As we before saw there is traceable throughout them an involved combination of rhythms. The unceasing circulation of water from the ocean to the land and from the land back to the ocean, is a type of these various compensating actions which, in the midst of all the irregularities produced by their mutual interferences, maintain an average. And in this, as in other equilibrations of the third order, we see that the energy ever in course of dissipation, is ever renewed from without: the rises and falls in the supply being balanced by rises and falls in the expenditure; as witness the variations of meteorologic activity in northern zones caused by changes of the seasons. But the fact it chiefly concerts us to note 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 temporary 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, all terrestrial changes are incidents in the course of cosmical equilibration. It was before pointed out (§69), that of the incessant alterations which the Earth's crust and atmosphere undergo, those which are not due to the action of the moon and 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 equilibrium; 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.

§173. 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 conditions; and finally in the arrest of vital movements at death. Let us consider the facts under these heads.

The sensible motion constituting each visible action of an animal, is soon brought to a close by some opposing force within or without the animal. When a man's 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 has to be immediately followed by another because the rapid dissipation of its momentum would otherwise soon bring the circulating mass to a stand. As much in the actions and reactions 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. The force stored up in food 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 rhythmical (§85); 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 muscular energy, there arises a reactive demand on those stores of energy which are laid up in the form of consumable matter throughout the tissues: increased respiration and increased circulation aid an extra genesis of force, that counterbalances 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 the prolonged draft on the spare capital in the tissues, is followed by a prolonged rest, during which the abstracted 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 destroy life (in which case 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 when some extreme 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. And this process exemplifies in a large way what physicians call the vis medicatrix naturae. The third form of equilibration displayed by organic bodies, is a 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. 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 like is manifestly the case with all organic modifications consequent on changes of climate or food. If we see that a different mode of life is followed, after a period of 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 called 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 latent energy balances the day's expenditure of actual energy. That is to say, during adult life there is continuously exhibited an equilibrium of the third order. Eventually, the daily loss begins to outbalance the daily gain, and 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 comes that complete equilibrium we call death.

The ultimate structural state accompanying that ultimate functional state towards which an organism tends, 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 reached when the equilibration of any aggregate becomes complete -- that the re-distribution of matter can continue so long only as there continues some motion unbalanced. What is the implication in the case of organic aggregates? We have seen that to maintain the moving equilibrium of one, 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 connexions of organs. Hence the structural complexity accompanying functional equilibrium, 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 §85, every species of plant and animal was shown to be perpetually undergoing a rhythmical variation in number -- now from abundance of food or absence of enemies rising above its average; and then, by a consequent scarcity of food or 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. 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.

§174. The equilibrations of those nervous actions which constitute the obverse face of 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 nerve force from moment to moment generated, (and it was explained in §86 that nerve currents are not continuous but rhythmical,) is met by counteracting forces, in overcoming which it is dispersed and equilibrated. Such part of it as does not work mental changes works bodily changes -- contractions of the involuntary muscles, the voluntary muscles, or both; as also some stimulation of secreting organs. That the movements thus initiated are ever being brought to a close by the opposing forces they evoke, we have just seen; and here it is to be observed that the like holds with the cerebral changes thus initiated. The arousing of a thought or feeling, 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 ordinary rapidity; instance the converse fact that at times of unusual energy, natural or artificial, thinking is easy, and more numerous, more remote, or more difficult connexions 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 passing conditions 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 as extending over hours and days, we discover equilibrations analogous to those hourly and daily established among the bodily functions. 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 energy 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, expressing itself in violent actions and loud sounds, presently reaches an extreme whence the counteracting forces produce 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 having a partially different medium state. But the kind of mental equilibration to be especially noted, is that shown in the establishment of a correspondence between relations among our ideas and relations in the external world. Each outer connexion of phenomena which we are capable of perceiving, generates, through accumulated experiences, an inner connexion of mental states; and the result towards which this process tends, is the formation of a mental connexion having a relative strength that answers to the relative constancy of the physical connexion 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 which will be more readily taken 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 connexion in consciousness; and this connexion, 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 happens that, answering to such uncertain relations of phenomena as that between clouds and rain, there arise relations of ideas of like uncertainty; and if, under given aspects of the sky, the tendencies to infer fair or foul weather, corresponds to the frequencies with which fair or foul weather follows 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 associations having different degrees of constancy, and that during the evolution of intelligence there arise answering eternal 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. The like general truths are exhibited in the process of moral adaptation, which is a continual approach to equilibrium between the emotions and the kinds of conduct required by surrounding conditions. 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. Thus 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 by every more frequent or more lengthened performance of it under such pressure, the resistance is somewhat diminished; then, dearly, 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 at length bring about a state in which this mode of directing the energies will be no more repugnant than the other modes previously natural to the race. Hence the limit towards which emotional modification perpetually tends, is a combination of desire that correspond to the various orders of activity which the circumstances of life call for. In acquired habits, and in the moral differences of races and nations that are produced by habits maintained through successive generations, we have illustrations of this progressive adaptation, which can cease only with the establishment of equilibrium between constitution and conditions.

§175. Each society 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 from side to side of that average number which the locality can support. Though, by artificial production unceasingly improved, 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 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 versa; 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 imply 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 in other kinds and amounts of motion by the labourer who purchases it. And the variations of price represent a rhythmical balancing of these forces. Every rise or fall 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 increased 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 they receive an amount of other commodities larger than before -- 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 that the total resistance overcome in obtaining a livelihood, 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, must multiply till there arises an approximate balance between its population and that of others available by the same citizens.

These various industrial actions and reactions constitute a dependent moving equilibrium like that maintained among the functions of an individual organism, and like it tends ever to become more complete. During early stages of social evolution, while 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. 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, 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 very imperfect. Great over-production of a commodity is followed by great under-production, and there results a rhythm having extremes that depart 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 grow into weekly markets, and these into daily markets, there is gradually produced a better balance of production and consumption: 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 in 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.

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. 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 separation. Contrariwise, those desires which can be fulfilled only by co-operation and those which find satisfaction through intercourse with fellow-men, as well as 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 man more or less of resistance against restraints imposed on his actions by other men -- a resistance which, tending ever to widen each man's sphere of action, and reciprocally to limit the spheres of action of other men, 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 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 separation. Like other opposing forces, those exerted by citizens on one another produce alternating movements which, at first extreme, undergo gradual diminution on the way to ultimate equilibrium. In small, undeveloped societies, marked rhythms result from these conflicting tendencies. A tribe that has maintained its unity for a generation or two, reaches a size at which it will no longer hold together; and, on the occurrence of some event causing unusual antagonism among its members, divides. Each primitive nation exhibits wide oscillations between an extreme in which the subjects are under rigid restraint, and an extreme in which the restraint fails to prevent rebellion and disintegration. In more advanced nations of like type, we always find violent actions and reactions of the same essential nature: "despotism tempered by assassination," characterizing a political state in which unbearable repression from time to time brings about a bursting of bonds. Among ourselves the conflicts between Conservatism (which stands for the restraints of society over the individual) and Reform (which stands for the liberty of the individual against society), fall within slowly approximating limits. so that the temporary predominance of either produces a less marked deviation from the medium state -- a smaller disturbance of the moving equilibrium.

Of course in this case, as in preceding cases, there is involved a limit to the increase of heterogeneity. A few pages back, it was shown that an advance in mental evolution is the establishment of some further internal action corresponding to some further external action. We inferred that each such new function, involving some new modification of structure, implies an increase of heterogeneity; and that thus, increase of heterogeneity must go on while there remain any outer relations affecting the organism which are unbalanced by inner relations. Evidently the like must simultaneously take place with society. Each increment of heterogeneity in the individual implies, as cause or consequence, some increment of heterogeneity in the arrangements of the aggregate of individuals. And the limit to social complexity can be reached only with the establishment of the equilibrium, just described, between social and individual forces.

§176. Here presents itself a final question, which has probably been taking shape in the minds of many while reading this chapter. "If Evolution of every kind is an increase in complexity of structure and function that is incidental to the universal process of equilibration, and if equilibration must end in complete rest, what is the fate towards which all things tend? If the Solar System is slowly dissipating its energies -- if the Sun is losing his heat at a rate which will tell in millions of years -- if with decrease of the Sun's radiations there must go on a decrease in the activity of geologic and meteorologic processes as well as in the quantity of vegetable and animal life -- if Man and Society are similarly dependent on this supply of energy which is gradually coming to an end; are we not manifestly processing towards omnipresent death?"

That such a state must be the outcome of the changes everywhere going on, seems beyond doubt. Whether any ulterior process may reverse these processes and initiate a new life, is a question to be considered hereafter. For the present it must suffice that the end of all the transformations we have traced, is quiescence. This admits of a priori proof. The law of equilibration, not less than the preceding general laws, is deducible from the ultimate datum of consciousness.

The forces of attraction and repulsion being, as shown in §74, universally co-existent, it follows that all motion is motion under resistance: either that exercised on the moving body by other bodies, or that exercised by the medium traversed. There are two corollaries. The first is that deductions perpetually made by the communication of motion to that which resists, cannot but bring the motion of the body to an end in a longer or shorter time. The second is that the motion of the body cannot cease until these deductions destroy it. In other words, movement must continue while equilibration is incomplete, and equilibration must eventually become complete. Both these are manifest deductions from the persistence of force. Hence this primordial truth is our warrant for the conclusions that the changes which Evolution presents cannot end until equilibrium is reached, and that equilibrium must at last be reached.

At the same time it follows that in every aggregate having compound motions, there results a comparatively early dissipation of the motions which are smaller and much resisted, followed by long-continuance of the larger and less resisted motions; and that so there arise moving equilibria. Hence, also, may be inferred the tendency to conservation of such moving equilibria. For any new motion given to the parts of a moving equilibrium by a disturbing force, must either be such that it cannot be dissipated before the pre-existing motions, in which case it brings the moving equilibrium to an end. or else it must be such that it can be dissipated before the pre-existing motions, in which case the moving equilibrium is re-established.

Thus from the persistence of force follow, not only the various direct and indirect equilibrations going on around, together with th at cosmical equilibration which brings Evolution under all its forms to a close, but also those less manifest equilibrations shown in the readjustments of moving equilibria that have been disturbed. By this ultimate principle is provable the tendency of every organism, disordered by some unusual influence, to return to a balanced state. To it also may be traced the capacity, possessed in a slight degree by individuals and in a greater degree by species, of becoming adapted to new circumstances. And not less does it afford a basis for the inference that there is a gradual advance towards harmony between man's mental nature and the conditions of his existence.

Chapter 23   Dissolution

§177. When, in Chapter 22, we glanced at the cycle of changes through which every existence passes, in a short time or in a time almost infinitely long -- when the opposite re-distributions of matter and motion implied were severally distinguished as Evolution and Dissolution. the natures of the two, and the conditions under which they respectively occur, were specified in general terms. Since then, we have contemplated the phenomena of Evolution in detail, and have followed them out to those states of equilibrium in which they all end. To complete the argument we must now contemplate, somewhat more in detail than before, the complementary phenomena of Dissolution. Not, indeed, that we need dwell long on Dissolution, which has none of those various and interesting aspects which Evolution presents; but something more must be said than has yet been said.

It was shown that neither of these two antagonist processes goes on unqualified by the other, and that a movement towards either is a differential result of the conflict between them. An evolving aggregate, while on the average losing motion and integrating, is always, in one way or other, receiving some motion and to that extent disintegrating; and after the integrative changes have ceased to predominate, the reception of motion, though perpetually checked by its dissipation, constantly tends to produce a reverse transformation, and eventually does produce it. When Evolution has run its course -- when an aggregate has reached that equilibrium in which its changes end, it thereafter remains subject to all actions in its environment which may increase the quantity of motion it contains, and which in course of time are sure, either slowly or suddenly, to give its parts such excess of motion as will cause disintegration. According as its size, its nature, and its conditions determine, its dissolution may come quickly or may be indefinitely delayed -- may occur in a few days or may be postponed for billions of years. But exposed as it is to the contingencies not simply of its immediate neighbourhood but of a Universe everywhere in motion, the time must at last come when, either alone or in company with surrounding aggregates, it has its parts dispersed.

The process of dissolution so caused we have here to look at as it takes place in aggregates of different orders. The course of change being the reverse of that hitherto traced, we may properly take the illustrations of it in the reverse order -- beginning with the most complex and ending with the most simple.

§178. Regarding the evolution of a society as at once an increase in the number of individuals integrated into a corporate body, an increase in the masses and varieties of the parts into which this corporate body divides, as well as of the actions called their functions, and an increase in the degree of combination among these masses and their functions; we shall see that social dissolution conforms to the general law in being, materially considered, a disintegration, and, dynamically considered, a decrease in the movements of wholes and an increase the movements of parts; while it further conforms to the general law in being, caused by an excess of motion in some way or other received from without.

It is obvious that the social dissolution which follows the aggression of mother nation, and which, as history shows us, is apt to occur when social evolution has ended and decay has begun, is, under its broadest, aspect, the reception of a new external motion; and when, as sometimes happens, the conquered society is dispersed, or when its component divisions fall apart, its dissolution is literally a cessation of those corporate movements which the society, both in its army and in its industrial bodies, presented, and a lapse into individual or uncombined movements.

Again, social disorder, however caused, entails a decrease of integrated movements and an increase of disintegrated movements. As the disorder progresses the political actions previously combined become uncombined: there arise the antagonistic actions of riot or revolt. Simultaneously, the industrial and commercial processes that were co-ordinated throughout the body politic, are broken up; and only the local, or small, trading transactions continue. And each further disorganizing change diminishes the joint operations by which men satisfy their wants, and leaves them to satisfy their wants, as best they can, by separate operations. Of the way in which such distintegrations are set up in a society that has evolved to the limit of its type, and reached a state of moving equilibrium, a good illustration is furnished by Japan. The finished fabric into which its people have organized themselves, maintained an almost constant state so long as it was preserved from fresh external forces. But as soon as it received an impact from European civilization, partly by armed aggression, partly by commercial impulse, partly by the influence of ideas, this fabric began to fall to pieces. There is now in progress a political dissolution.*<* This was written in 1867.> Probably a political reorganization will follow; but, be this as it may, the change thus far produced by an outer action is a change towards dissolution -- a change from integrated motions to disintegrated motions.

Even where a society that has developed into the highest form permitted by the characters of its units, begins to dwindle and decay, the progressive dissolution is still essentially of the same nature. Decline of numbers is, in such case, brought about partly by emigration; for a society having the fixed structure in which evolution ends, is one that will not yield and modify under pressure of population: so long as its structure is plastic it is still evolving. Hence the surplus population is continually dispersed: the influences brought to bear on the citizens by other societies cause their detachment, and there is an increase of the uncombined motions of units instead of an increase of combined motions. Gradually as the society becomes still less capable of changing into the form required for successful competition with more plastic societies, the number of citizens who can live within its unyielding framework becomes positively smaller. Hence it dwindles both through continued emigration and through the diminished multiplication that follows innutrition. And this further dwindling is similarly a decrease in the total quantity of combined motion and an increase in the quantity of uncombined motion -- as we shall presently see when we come to deal with individual dissolution.

Considering, then, that social aggregates differ so much from aggregates of other kinds, formed, as they are, of units held together loosely and indirectly, in such variable ways by such complex forces, the processes of dissolution among them conforms to the general law quite as clearly as could be expected.

§179. When from these super-organic aggregates we descend to organic aggregates, the truth that Dissolution is a disintegration of matter caused by the reception of additional motion from without, becomes easily demonstrable. We will look first at the transformation and afterwards at its cause.

Death, or that final equilibration which precedes dissolution, is the bringing to a close all those many conspicuous integrated motions that arose during evolution. The impulsions of the body from place to place first cease; presently the limbs cannot be stirred; later still the respiratory actions stop; finally the heart becomes stationary and, with it, the circulating fluids. That is, the transformation of molecular motion into the motion of masses, comes to an end. The process of decay involves an increase of insensible movements; since these are far greater in the gases generated than they are in the fluid-solid matters out of which the gases arise. Each of the complex chemical units composing an organic body, possesses a rhythmic motion in which its many component units jointly partake. When decomposition breaks up these complex molecules, and their constituents assume gaseous forms, there is, besides that increase of motion implied by diffusion, a resolution of such motions as the complex molecules possessed, into motions of their constituent molecules. So that in organic dissolution we have, first, an end put to that transformation of the motions of units into the motions of aggregates, which constitutes evolution, dynamically considered; and we have afterwards, though in a subtler sense, a transformation of the motions of aggregates into the motions of units. Still it is not thus shown that organic dissolution answers to the general definition of dissolution -- the absorption of motion and concomitant disintegration of matter. The disintegration of matter is, indeed, conspicuous enough; but the absorption of motion is not conspicuous. True, the fact that motion has been absorbed may be inferred from the fact that particles previously integrated into a solid mass, occupying a small space, have most of them moved away from one another and now occupy a great space; for the motion implied by this expansion must have been obtained from somewhere. But its source is not obvious. A little search, however, will bring us to its derivation.

At a temperature below the freezing point of water, decomposition of organic matter does not take place. Dead bodies kept at this temperature are prevented from decomposing for an indefinitely long period: witness the frozen carcases of mammoths (elephants of a species long ago extinct) that are found imbedded in the ice at the mouths of Siberian rivers; and which, though they have been there for many thousands of years, have flesh so fresh that when at length exposed it is devoured by wolves. What, now, is the meaning of such exceptional preservations? A body kept below freezing point, is a body which receives very little heat by radiation or conduction; and the reception of but little heat is the reception of but little molecular motion. That is to say,in an environment which does not furnish it with molecular motion passing a certain amount, an organic body does not undergo dissolution. Confirmatory evidence is yielded by the variations in rate of dissolution which accompany variations of temperature. All know that in cool weather the organic substances used in our households keep longer, as we say, than in hot weather. Equally certain, if less familiar, is the fact that in tropical climates decay proceeds much more rapidly than in temperate climates. Thus, dispersion of the dead body into gases is rapid in proportion as the molecular motion received from without is great. The still-quicker decompositions produced by exposure to artificially-raised temperatures, afford further proofs: instance those which occur in cooking. The charred surfaces of parts much heated, show us that the molecular motion absorbed has served to dissipate in gaseous forms all the elements but the carbon.

The nature and causes of Dissolution are thus clearly displayed by the aggregates which so clearly display the nature and causes of Evolution. One of these aggregates being made of that peculiar matter to which a large quantity of constitutional motion gives great plasticity, and the ability to evolve into a highly complex form, (§103); it results that after evolution has ceased, a small amount of molecular motion added to that already contained in its peculiar matter, suffices to cause dissolution. Though at death there is reached an equilibrium among the sensible masses, or organs, which make up the body; yet, as the insensible units or molecules of which these organs consist are chemically unstable, small incident forces suffice to overthrow them, and hence disintegration proceeds rapidly.

§180. Most inorganic aggregates, having arrived at dense forms in which comparatively little motion is retained, remain long without marked changes. Each has lost so much motion in passing from the unintegrated to the integrated state, that much motion must be given to it to cause resumption of the unintegrated state; and an immense time may elapse before there occur in the environment, changes great enough to communicate to it the requisite quantity of motion. We will look first at those few inorganic aggregates which retain much motion, and therefore readily undergo dissolution.

Among these are the liquids and volatile solids which dissipate under ordinary conditions -- water that evaporates, camphor that wastes away by the dispersion of its molecules. In all such cases motion is absorbed; and always the dissolution is rapid in proportion as the quantity of heat or motion which the mass receives from its environment is great. Next come the cases in which the molecules of a highly integrated or solid aggregate, are dispersed among the molecules of a less integrated or liquid aggregate; as in aqueous solutions. One evidence that this disintegration of matter has for its concomitant the absorption of motion, is that soluble substances dissolve the more quickly the hotter the water: supposing always that no elective affinity comes into play. Another and still more conclusive evidence is, that when crystals of a given temperature are placed in water of the same temperature, the process of solution is accompanied by a fall of temperature -- often a very great one. Omitting instances in which some chemical action takes place between the salt and the water, it is a uniform law that the motion which disperses the molecules of the salt through the water, is at the expense of the molecular motion possessed by the water. An allied and still better example is furnished by cases in which the dissolution of two solids results from mixing them, as happens with snow and salt. Here dissolution necessitates so great an absorption of molecular motion as greatly to lower the temperature of the liquid produced.

Masses of sediment accumulated into strata, afterwards compressed by many thousands of feet of superincumbent strata, and reduced in course of time to a solid state, may remain for untold millions of years unchanged; but in subsequent millions of years they are inevitably exposed to disintegrating actions. Raised along with other such masses into a continent, denuded and exposed to rain, frost, and the grinding actions of glaciers, they have their particles gradually separated, carried away, and widely dispersed. Or when, as otherwise happens, the encroaching sea arrives, the undermined cliffs formed of them fall from time to time; the waves, rolling about the small pieces, and in storms knocking together the larger blocks, reduce them to boulders and pebbles, and at last to sand and mud. Even if portions of the disintegrated strata accumulate into shingle banks which afterwards become solidified, the process of dissolution, arrested though it may be for some enormous geologic period, is finally resumed. As many a shore shows us, the conglomerate itself is sooner or later subject to the like processes; and its cemented masses of heterogeneous components are broken up and worn away by impact and attrition -- that is, by communicated mechanical motion.

When not thus effected, the disintegration is effected by communicated molecular motion. A consolidated stratum in some area of subsidence, brought down nearer and nearer to the regions occupied by molten matter, comes eventually to have its particles brought to a plastic state by heat, or finally melted down into liquid. Whatever may be its subsequent transformations, the transformation then exhibited by it is an absorption of motion and disintegration of matter.

Thus be it simple or compound, small or large, a crystal or a mountain-chat, every inorganic aggregate on the Earth undergoes, at some time or other, a reversal of those changes undergone during its evolution. Not that it usually passes back from the perceptible into the imperceptible, during any period in which it is or can be exposed to human observation. It does not become aeriform and invisible, as organic aggregates do in great part, though not wholly. But still its disintegration and dispersion carry it some distance on the way towards the imperceptible; and there are reasons for thinking that its arrival there is but delayed. At a period immeasurably remote, every such inorganic aggregate, along with all undissipated remnants of organic aggregates, must be reduced to a state of gaseous diffusion, and so complete the cycle of its changes.

§181. For the Earth as a whole, when it has gone through the entire series of its ascending transformations, must remain exposed to the contingencies of its environment; and in the course of those ceaseless changes going on throughout a Universe of which all parts are in motion, must, at some period beyond the utmost stretch of imagination, be subject to energies sufficient to cause its complete disintegration. Let us glance at the energies competent to disintegrate it.

In his essay on "The Inter-action of Natural Forces," Prof. Helmholtz states the thermal equivalent of the Earth's movement through space, as calculated on the now received datum of Mr. Joule. "If our Earth," he says, "were by a sudden shock brought to rest in her orbit -- which is not to be feared in the existing arrangement of our system -- by such a shock a quantity of heat would be generated equal to that produced by the combustion of fourteen such Earths of solid coal. Making the most unfavourable assumption as to its capacity for heat, that is, placing it equal to that of water, the mass of the Earth would thereby be heated 11,200 degrees; it would therefore be quite fused, and for the most part reduced to vapour. If then the Earth, after having been thus brought to rest, should fall into the Sun, which of course would be the case, the quantity of heat developed by the shock would be 400 times greater." Now though this calculation seems to be nothing to the purpose, since the Earth is not likely to be suddenly arrested in its orbit and not likely therefore suddenly to fall into the Sun; yet, as before pointed out (§171), there is a force at work which it is held must at last bring the Earth into the Sun. This force is the resistance of the ethereal medium. From ethereal resistance is inferred a retardation of all moving bodies in the Solar System -- a retardation which some astronomers contend even now shows its effects in the relative nearness to one another of the orbits of the older planets. If, then, retardation is going on, there must come a time, no matter how remote, when the slowly diminishing orbit of the Earth will end in the Sun; and though the quantity of molar motion to be then transformed into molecular motion, will not be so great as that which the calculation of Helmholtz supposes, it will be great enough to reduce the substance of the Earth to a gaseous state.

This dissolution of the Earth and, at intervals, of every other planet, is not, however, a dissolution of the Solar System. All the changes exhibited throughout the Solar System, are incidents accompanying the integration of the entire matter composing it: the local integration of which each planet is the scene, completing itself long before the general integration is complete. But each secondary mass leaving gone through its evolution and reached a state of equilibrium among its parts (supposing that the available time suffices, which in the cases of Jupiter and Saturn it may not), thereafter continues in its extinct state, until, by the still-progressing general integration, it is brought into the central mass. And though each such union of a secondary mass with the central mass, implying transformation of molar motion into molecular motion, causes partial diffusion of the total mass formed, and adds to the quantity of motion that has to be dispersed in the shape of light and heat; yet it does but postpone the period at which the total mass must become completely integrated, and its excess of contained motion radiated into space.

§182. Here we come to the question raised at the close of the last chapter -- Does Evolution as a whole, like Evolution in detail, advance towards complete quiescience? Is that motionless state called death, which ends Evolution in organic bodies, typical of the universal death in which Evolution at large must end? And have we thus to contemplate as the outcome of things, a boundless space holding here and there extinct Suns, fated to remain for ever without further change?

To so speculative an inquiry, none but a speculative answer is to be expected. Such answer as may be ventured, must be taken less as a positive answer than as a demurrer to the conclusion that the proximate result must be the ultimate result. If, pushing to its extreme the argument that Evolution must come to a close in complete equilibrium or rest, the reader suggests that for aught which appears to the contrary there must result a Universal Death which will continue indefinitely, two replies may be made. The first is that the evidence presented in the heavens at large implies that while of the multitudinous aggregates of matter it presents, most are passing through those stages -- which must end in local rest, there are others which, having barely commenced the series of changes constituting Evolution, are on the way to become theatres of life. The second reply is that when we contemplate our Sidereal System as a whole, certain of the great facts which science has established imply potential renewals of life, now in one region now in another, followed, possibly, at a period unimaginably remote by a more general renewal. This conclusion is suggested when we take into account a factor not yet mentioned.

For hitherto we have considered only that equilibration which is taking place within our Solar System and within similar systems; taking no note of that immeasurably greater equilibration which remains to take place: ending those motions through space which such systems possess. That the stars, in old times called fixed, are all in motion, has now become a familiar truth, and that they are moving with velocities ranging from say 10 miles per second up to some 70 miles per second (which last is the velocity of a "runaway star" supposed to be passing through our Sidereal System) is a truth deduced from observations by modern astronomers. To be joined with this is the fact that there are dying stars and probably dead stars. Beyond the evidence furnished by the various kinds of light they emit, of which the red indicates relatively advanced age, there is the evidence that in some cases bright stars have attendants which are dark or almost dark: the most conspicuous case being that of Sirius, round which revolves a body of about one-third its size but yielding only 1/30000th part of its light -- a star approaching to our Sun in size, which has gone out. The implication appears to be that beyond the luminous masses constituting the visible Sidereal System, there are non-luminous masses, perhaps fewer in number perhaps more numerous, which in common with the luminous ones are impelled by mutual gravitation. How then are to be equilibrated the motions of these vast masses, luminous and nonluminous, having high velocities?

This question may be divided into two, a major and a minor, of which the minor admits of something like an answer, while the major seems unanswerable.

§182a. Scattered through immensurable space, but more especially in and about the region of the Milky Way, are numerous star-clusters, varying in their characters from those which are hardly distinguishable from unusually rich portions of the heavens, to those which constitute condensed swarms of stars; kinds of which may be named, as at the one extreme, 24 Persei, 103 Cassiopeia and 32 Cygni, and at the other extreme, 13 Herculis and 2 Aquarei.(*)<fn* The clusters here named are exhibited in Dr. Isaac Roberts's splendid series of Photographs of Stars, Star-Clusters, and Nebulae (two vols.), in which also will be found the references presently to be made.> The varieties between these extremes were regarded by Sir William Herschel as implying progressive concentration; and in his opinion Sir John Herschel apparently agreed. Pursuing the argument the latter wrote: --

"Among a crowd of solid bodies of whatever size, animated by independent and partially opposing impulses, motions opposite to each other must produce collision, destruction of velocity, and subsidence or near approach towards the centre of preponderant attraction; while those which conspire, or which remain outstanding after such conflicts, must ultimately give rise to circulation of a permanent character." (Outlines of Astronomy, 9th ed., p. 641.) The problem, however, is here dealt with purely as a mechanical one: the assumption being that the mutually arrested masses will continue as masses. Writing in 1849 Sir John Herschel did not take account of the results reached and verified during the few preceding years by Mayer and Joule, respecting the quantitative equivalence between motion and heat. But accepting, as we must now do, the conclusion drawn by Helmho1tz (§171) congruous with one previously drawn by Mayer, we are obliged to infer that stars moving at the high velocities acquired during concentration, will, by mutual arrest, be dissipated into gases of extreme tenuity constituting what we conceive as nebulous matter. When we infer this the problem becomes different; and a different conclusion seems unavoidable. For the diffused matter produced by such conflicts must form a resisting medium, occupying that central region of the cluster through which its members from, time to time pass in describing their orbits -- a resisting medium which they cannot move through without having their velocities diminished. Every additional collision, by augmenting this resisting medium, and making the losses of velocity greater must aid in preventing the establishment of that equilibrium which would else arise; and so must conspire to produce more frequent collisions. And the nebulous matter thus formed, presently enveloping the whole cluster, must, by continuing to shorten the gyrations of the moving masses, entail an increasingly active integration and reactive disintegration of them, until they are all dissipated.*

<* I leave these three sentences as they stood in the revised edition of this work published in 1867, because evidence since obtained goes far to show that the process described is going on. In the photographs contained in the second volume of his Stars, Star-Clusters, and Nebulae, and by the accompanying description; Dr. Roberts shows that in some of them (as instance, M. 3 Canum Venaticorum) there is distinctly visible a nebulous central region, such as might be produced at early stages of the process described; and that he conceives such a process to be taking place is proved by his remarks on page 178.>

Products of the kind implied are presented in the large diffused, and irregular nebulae, such as the one in Orion Sir John Herschel describes them (p. 650) as "very great in extent," "irregular and capricious in their shapes," "no less so in the distribution of their light," and not having "any similarity of figure or aspect." And then he remarks that "they have one important character in common" -- "they are all situated in or near the borders of the Milky Way." That is to say, they are found in that region of the heavens in which star-clusters also are most abundant. Thus in their distribution and in their characters these nebulae are congruous with the supposition that they have resulted from dissipation of clusters arising in the way described.

What may we say concerning the future of one of these vast irregular nebulae? The first remark is that as, in conformity with the foregoing speculation, it contains the matter not of one star but of many stars, so in conformity with its aspect it is not a nebulous mass of the kind out of which a single star or sun originates: being so large that it covers numerous interstellar spaces. The second remark is that when its widest diffusion has been reached concentration will commence, and the implication is that after an immense period a rotating nebula of one or other of the kinds so abundantly exemplified will result. That a spiral nebula is produced by concentration of one of these vast diffused masses, containing the matter of many stars, is an inference supported by the fact that in some spiral nebulae many stars and nebulous stars embedded within the spiral structure have manifestly been formed or are forming while the general concentration is going on -- instance 74 Piscium, 100 Comae, and M. 51 Canum Venaticorum -- and suggesting that a new concentrating cluster will eventually arise. If so, the implication appears to be that there will eventually again arise a process like that just suggested -- collisions of concentrating masses and progressing diffusion until the nebulous form is again produced.

If in pursuance of this view we regard (1) the star-clusters variously condensed, (2) the diffused and irregular nebulae, (3) the spiral and other nebulae that are concentrating into star-systems, as exhibiting different stages of the same process, then the implication is that in many thousands of places throughout our Sidereal System there are going on alterations of Evolution and Dissolution. And this conception may be taken as a sufficient answer to the inference above drawn that equilibration must end in universal death -- a speculative demurrer to a speculative conclusion.

§182b. There still presents itself the question which, unanswerable though it may be, we cannot ignore -- What are we to think concerning the future of the visible Universe? To the conception of alternating evolutions and dissolutions taking place in multitudinous different parts of it, there must be joined the conception of it as either remaining in its present state or as changing; and that rises the question -- Changing towards what other state? That its state must change is clear: the irregular distribution of it being such as to render even a temporary moving equilibrium impossible.

At the outset there arises the doubt whether our Sidereal System is an aggregate at all, in such sense as is implied by conformity to the law of Evolution and Dissolution -- whether it does not transcend those limits implied by conformity to the law. When, reducing its stars and their distances to dimensions that may be imagined, we think of them as comparable to peas one hundred miles apart, the conception of them as forming a whole held together only by mutual gravitation seems somewhat strained. The assumed unity seems more questionable on observing the marks of independence in the dispersed parts. Besides multitudinous cases of the kind above described in which star-clusters apparently carry on their transformations irrespective of the Sidereal System as a whole, there are some far larger local transformations that appear to be of kindred nature. I refer to those going on in the Magellanic clouds or nubeculae, major and minor -- two closely-packed agglomerations, not, indeed, of single stars only, but of single stars, of clusters regular and irregular, of nebula, and of diffused nebulosity. That these have been formed by mutual gravitation of parts once widely scattered, there is evidence in the barrenness of the surrounding celestial spaces: the nubecula minor especially, being seated, as Humboldt says, in "a kind of starless desert." And since the traits of these chaotic aggregates are such as do not consist with any process of evolution, we must infer that they are passing through the counter-process of dissolution: the resulting nebulous matter having already enveloped large portions of their miscellaneous components; a conclusion receiving support from the fact that while the one lies in a space devoid of stars the other has around it numerous outlying nebula and star-clusters, which must in course of time be drawn into it. Thus there are considerable difficulties in the way of regarding our Sidereal System as a whole, subject to the processes of evolution and dissolution.

Nevertheless sundry traits seem to imply that throughout a past so immense that the time occupied in the evolution of a solar or stellar system becomes by comparison utterly insignificant, there has been a gathering together of the matter of our Universe from a more dispersed state; and its disc-like form, or else annular form, indicated by the encircling appearance of the Milky Way, rises the thought that it has a combined motion within which all minor motions are included. Moreover the contrast between the galactic circle, with its closely packed millions of stars dotted with numerous star-clusters, and the regions about the galactic poles, in which the more regular nebula are chiefly congregated, yields further evidence that our Sidereal System has some kind of unity, and that during an immeasurable past it has undergone transformations due to general forces. If, then, we must contemplate the visible Universe as an aggregate, subject to processes of evolution and dissolution of the same essential nature as those traceable in minor aggregates, we cannot avoid asking what is likely to be its future.

In his Outlines of Astronomy (pp. 630-1), Sir John Herschel refers to speculations respecting the rotation of our Sidereal System in the plane of the galactic circle. Dismissing the hypothesis of Mädler that the centre of rotation is in the Pleiades, he thinks that no opinion can reasonably be formed whether rotation exists or not, until after some thirty or forty years of observations of a special class. In any case, however, the irregularities of the Milky Way necessitate the conclusion that there is going on, and must continue to go on, a general change of structure. The greater massiveness of it in the northern than in the southern hemisphere, the cleft form, the breach of continuity, the branchings, the narrow connecting necks, and the parts that are almost or quite islanded, exclude the idea of equilibrium, whether the system as a whole be stationary or whether it be rotating. In §150, when referring to the fate of nebulous rings, I cited the option of Sir John Herschel to the effect that a nebulous ring would not break at one place and collapse, but would break at many places and form separate masses. I joined with it the opinion of Sir G. B. Airy, to whom I put the question whether these would remain separate, and who agreed that the masses thus formed, parting more widely at some one place, would eventually collapse into a single mass. Parallel conclusions respecting changes in the Milky Way seem legitimate, or rather, indeed, seem necessitated. Separation of it into parts -- minor Sidereal Systems -- is a result to which its present aspect points. That such minor sidereal systems could remain permanently independent is not to be supposed. Mutual attraction would cause in some cases the formation of binary sidereal systems, and in other cases coalescence, according to the directions and amounts of their respective proper motions. The implication is that there may be repeated, on vaster scales, changes like those described as occurring in star-clusters: local concentrations taking place within these minor sidereal systems, with resulting evolutions and dissolutions, at the same time that the minor sidereal systems themselves, progressively uniting, become more condensed, and consequently the scenes of more active changes of like kinds. If, giving imagination the rein, we suppose this process carried to its limit, and ultimately to present on an immensely larger scale the kind of change which the nubeculae exhibit, there arises the thought of a progressing destruction of the molar motions possessed by the concentrating stars, and a simultaneous diffusion of their substances, which, as the process comes to a close, spreads the matter of the Sidereal System in its nebulous form throughout the whole of that space which it originally filled -- a diffusion reversing the preceding concentration -- a dissolution that prepares the way for a new evolution. Reduced to its abstract form, the argument is that the quantity of motion implied by dispersion must be as great as the quantity of motion implied by aggregation, or rather must be the same motion, taking now the molar form and now the molecular form; and if we allow ourselves to conceive this as an ultimate result there arises the conception not only of local evolutions and dissolutions throughout our Sidereal System but of general evolutions and dissolutions alternating indefinitely.

But we cannot draw such a conclusion without tacitly assuming something beyond the limits of possible knowledge, namely, that the energy contained in our Sidereal System remains undiminished. Continuance of such alterations without end presupposes that the quantity of molecular motion radiated by each star in the course of its formation from diffused matter, shall either not escape from our Sidereal System or shall be compensated by an equal quantity of molecular motion radiated into it from other parts of space. If the ether which fills the interspaces of our Sidereal System has a boundary somewhere beyond the outermost stars, it is inferable that motion is not lost by radiation beyond that boundary; and if so the original degree of diffusion may be resumed. Or if, supposing that the ether is unbounded, the temperature of space is the same within and without our Sidereal System, then it is inferable that the quantity of motion contained within our Sidereal System remaining undiminished, its alternate concentrations and diffusions may continue undiminished. But we shall never be able to say whether either condition is fulfilled.

We may indeed dismiss such questions as passing the bounds of rational speculation. They have here been touched upon for the purpose of showing that it is not inferable from the general progress towards equilibrium that a state of universal quiescence or death will be reached; but that if a process of reasoning ends in that conclusion, a further process of reasoning points to renewals of activity and life.

Here, however, it is needless for the adequate presentation of the general doctrine, that Evolution and Dissolution should be traced in either direction to their ends. In §93 it was said that no actual philosophy can fill out the scheme of an ideal philosophy -- cannot even of a small aggregate trace the entire history from its appearance to its disappearance, and must be immeasurably far from doing this with the all-comprehensive aggregate.

But unable though we must ever remain to give a complete account of the transformation of things, even in any of its minor parts, and still more in its totality we are able to recognize throughout it the same general law; and may reasonably infer that it holds in those parts of the transformation which are beyond the reach of our intelligence as it does in those parts which are within its reach.

Chapter 24   Summary and Conclusion

§184. At the close of a work like this, it is more than usually needful to contemplate as a whole that which the successive chapters have presented in parts. A coherent knowledge implies something more than the establishment of connexions: we must not rest after seeing how each minor group of truths falls into its place within some major group, and how all the major groups fit together. It is requisite that we should retire a space, and, looking at the entire structure from a distance at which details are lost to view, observe its general character.

Something more than recapitulation -- something more even than an organized re-statement, will come within the scope of the chapter. We shall find that in their ensemble the general truths reached exhibit, under certain aspects, a oneness not hitherto observed.

There is, too, a special reason for noting how the various divisions and subdivisions of the argument consolidate; namely, that the theory at large thereby obtains a final illustration. The reduction of the generalizations which have been set forth separately to a completely integrated state, exemplifies once more the process of Evolution, and strengthens still further the general fabric of conclusions.

§185. Here, indeed, we find ourselves brought round unexpectedly to the truth with which we set out, and with which our re-survey must commence. For this integrated form of knowledge is the form which, apart from the doctrine of Evolution, we decided to be the highest form.

When we inquired what constitutes Philosophy -- when we compared men's various conceptions of Philosophy, so that, eliminating the elements in which they differed, we might see in what they agreed; we found in them all the tacit implication that Philosophy is completely unified knowledge. Apart from each scheme of unified knowledge, and apart from proposed methods by which unification is to be effected, we traced in every case a belief that unification is possible, and that the end of Philosophy is achievement of it.

After reaching this conclusion we considered the data with which Philosophy must set out. Fundamental propositions, or propositions not deducible from deeper ones can be established only by showing the complete congruity of all the results reached through the assumption of them; and, premising that they were simply assumed till thus established, we took as our data those components of our intelligence without which there cannot go on the mental processes implied by philosophizing.

From the specification of these we passed to certain primary truths -- "The Indestructibility of Matter," "The Continuity of Motion," and "The Persistence of force;" of which the last is ultimate and the others derivative. Having previously seen that our experiences of Matter and Motion are resolvable into experiences of force, we further saw the truths that Matter and Motion are unchangeable in quantity, to be implications of the truth that Force is unchangeable in quantity. This we concluded is the truth by derivation from which all other truths are to be proved.

The first of the truths which presented itself to be so proved, is "The Persistence of the relations among Forces." This, which is ordinarily called Uniformity of Law, we found to be a necessary implication of the truth that Force can neither arise out of nothing nor lapse into nothing.

The next deduction was that forces which seem to be lost are transformed into their equivalents of other forces; or, conversely, that forces which become manifest, do so by disappearance of pre-existing equivalent forces. These truths we found illustrated by the motions of the heavenly bodies, by the changes going on over the Earth's surface, and by all organic and super-organic actions.

It was shown to be the same with the law that everything moves along the line of least resistance, or the line of greater traction, or their resultant. Among movements of all orders, from those of stars down to those of nervous discharges and commercial currents, it was shown both that this is so, and tat, given the Persistence of Force, it must be so.

So, too, we saw it to be with "The Rhythm Of Motion." All motion alternates -- be it the motion of planets in their orbits or ethereal molecules in their undulations be it the cadences of speech or the rises and falls of prices; and, as before, it became manifest that Force being persistent, this perpetual reversal of Motion between limits is inevitable.

§186. These truths holding of existences at large, were recognized as of the kind required to constitute what we distinguish as Philosophy. But, on considering them, we perceived that as they stand they do not form a Philosophy. and that a Philosophy cannot be formed by any number of such truths separately known. Each expresses the law of some one factor by which phenomena, as we experience them, are produced; or, at most, expresses the law of co-operation of some two factors. But knowing what are the elements of a process, is not knowing how these elements combine to effect it. That which alone can unify knowledge must be the law of co-operation of the factors -- a law expressing simultaneously the complex antecedents and the complex consequents which any phenomenon as a whole presents.

A further inference was that Philosophy, as we understand it, must not unify the changes displayed in separate concrete phenomena only; and must not stop short with unifying the changes displayed in separate classes of concrete phenomena; but must unify the changes displayed in all concrete phenomena. If the law of operation of each factor holds true throughout the Cosmos, so, too, must the law of their co-operation. And hence in comprehending the Cosmos as conforming to this law of co-operation, must consist that highest unification which Philosophy seeks.

Descending to a more concrete view, we saw that the law sought must be the law of the continuous re-distribution of Matter and Motion. The changes everywhere going on, from those which are slowly altering the structure of our galaxy down to those which constitute a chemical decomposition, are changes in the relative positions of component parts; and everywhere necessarily imply that along with a new arrangement of Matter there has arisen a new arrangement of Motion. Hence it follows that there must be a law of the concomitant redistribution of Matter and Motion which holds of every change, and which, by thus unifying all changes, must be the basis of a Philosophy.

In commencing our search for this universal law of re-distribution, we contemplated from another point of view the problem of Philosophy, and saw that its solution could not but be of the nature indicated. It was shown that an ideally complete Philosophy must formulate the whole series of changes passed through by existences separately and as a whole in passing from the imperceptible to the perceptible and again from the perceptible to the imperceptible. If it begins its explanations with existences that already have concrete forms, or leaves off while they still retain concrete forms, then, manifestly, they had preceding histories, or will have succeeding histories, or both, of which no account is given. Whence we saw it to follow that the formula sought, equally applicable to existences taken singly and in their totality, must be applicable to the whole history of each and to the whole history of all. This must be the ideal form of a Philosophy, however far short of it the reality may fall.

By these considerations we were brought within view of the formula. For if it had to express the entire progress from the imperceptible to the perceptible and from the perceptible to the imperceptible; and if it Was also to express the continuous re-distribution of Matter and Motion, then, obviously, it could be no other than one defining the opposite processes of concentration and diffusion in terms of Matter and Motion. And if so, it must be a statement of the truth that the concentration of Matter implies the dissipation of Motion, and that, conversely, the absorption of Motion implies the diffusion of Matter.

Such, in fact, we found to be the law of the entire cycle of changes passed through by every existence. Moreover we saw that besides applying to the whole history of each existence, it applies to each detail of the history. Both processes are going on at every instant. but always there is a differential result in favour of the first or the second. And every change, even though it be only a transposition of parts, inevitably advances the one process or the other.

Evolution and Dissolution, as we name these opposite transformations, though thus truly defined in their most general characters, are but incompletely defined; or rather, while the definition of Dissolution is sufficient, the definition of Evolution is extremely insufficient. Evolution is always an integration of Matter and dissipation of Motion; but it is in nearly all cases much more than this. The primary re-distribution of Matter and Motion is accompanied by secondary re-distributions.

Distinguishing the different kinds of Evolution thus produced as simple and compound, we went on to consider under what conditions the secondary re-distributions which make Evolution compound, take place. We found that a concentrating aggregate which loses its contained motion rapidly, or integrates quickly, exhibits only simple Evolution; but in proportion as its largeness, or the peculiar constitution of its components, hinders the dissipation of its motion, its parts, while undergoing that primary re-distribution which results in integration, undergo secondary re-distributions producing more or less complexity.

§187. From this conception of Evolution and Dissolution as together making up the entire process through which things pass; and from this conception of Evolution as divided into simple and compound; we went on to consider the law of Evolution, as exhibited among all orders of existences, in general and in detail.

The integration of Matter and concomitant dissipation of Motion, was traced not in each whole only, but in the parts into which each whole divides. By the aggregate Solar System, as well as by each planet and satellite, progressive concentration has been, and is still being, exemplified. In each organism that general incorporation of dispersed materials which causes growth, is accompanied by local incorporations, forming what we call organs. Every society, while it displays the aggregative process by its increasing mass of population, displays it also by the rise of dense masses on special parts of its area. And in all cases, along with these direct integrations there go the indirect integrations by which parts are made mutually dependent.

From this primary re-distribution we were led on to consider the secondary re-distributions, by inquiring how there came to be a formation of parts during the formation of a whole. It turned out that there is habitually a passage from homogeneity to heterogeneity along with the passage from diffusion to concentration. While the matter composing the Solar System has been assuming a denser form, it has changed from unity to variety of distribution. Solidification of the Earth has been accompanied by a progress from comparative uniformity to extreme multiformity. In the course of its advance from a germ to a mass of relatively great bulk, every plant and animal also advances from simplicity to complexity. The increase of a society in numbers and consolidation has for its concomitant an increased heterogeneity both of its political and its industrial organization. And the like holds of all super-organic products -- Language, Science, Art, and Literature.

But we saw that these secondary re-distributions are not thus completely expressed. While the parts into which each whole is resolved become more unlike one another, they also become more sharply marked off. The result of the secondary re-distribution is therefore to change an indefinite homogeneity into a definite heterogeneity. This additional trait also we found in evolving aggregates of all orders. Further consideration, however, made it apparent that the increasing definiteness which goes along with increasing heterogeneity is not an independent trait, but that it results from the integration which progresses in each of the differentiating parts, while it progresses in the whole they form.

Further, it was pointed out that in all evolutions, inorganic, organic, and super-organic, this change in the arrangement of Matter is accompanied by a parallel change in the arrangement of contained Motion: every increase in structural complexity involving a corresponding increase in functional complexity. It was shown that along with the integration of molecules into masses, there arises an integration of molecular motion in to the motion of masses; and that as fast as there results variety in the sizes and forms of aggregates and their relations to incident forces, there also results variety in their movements.

The transformation thus contemplated under separate aspects, being in itself but one transformation, it became needful to unite these separate aspects into a single conception -- to regard the primary and secondary redistributions as simultaneously working their various effects. Everywhere the change from a confused simplicity to a distinct complexity, in the distribution of both matter and motion, is incidental to the consolidation of the matter and the loss of its internal motion. Hence the re-distribution of the matter and of its retained motion, is from a relatively diffused, uniform, and indeterminate arrangement, to a relatively concentrated, multiform, and determinate arrangement.

§188. We come now to one of the additions that may be made to the general argument while summing it up. Here is the fit occasion for observing a higher degree of unity in the foregoing inductions, than we observed while making them.

The law of Evolution has been thus far contemplated as holding true of each order of existences, considered as a separate order. But the induction as so presented, falls short of that completeness which it gains when we contemplate these several orders of existences as forming together one natural whole. While we think of Evolution as divided into astronomic, geologic, biologic, psychologic, sociologic, etc., it may seem to some extent a coincidence that the same law of metamorphosis holds throughout all its divisions. But when we recognize these divisions as mere conventional groupings, made to facilitate the arrangement and acquisition of knowledge -- when we remember that the different existences with which they severally deal are component parts of one Cosmos; we see at once that there are not several kinds of Evolution having certain traits in common, but one Evolution going on everywhere after the same manner, We have repeatedly observed that while any whole is evolving, there is always going on an evolution of the parts into which it divides itself; but we have not observed that this equally holds of the totality of things, which is made up of parts within parts from the greatest down to the smallest. We know that while a physically-cohering aggregate like the human body is getting larger and taking on its general shape, each of its organs is doing the same; that while each organ is growing and becoming unlike others, there is going on a differentiation and integration of its component tissues and vessels; and that even the components of these components are severally increasing and passing into more definitely heterogeneous structures. But we have not duly remarked that while each individual is developing, the society of which he is an insignificant unit is developing too; that while the aggregate mass forming a society is integrating and becoming more definitely heterogeneous, so, too, that total aggregate, the Earth, is continuing to integrate and differentiate; that while the Earth, which in bulk is not a millionth of the Solar System, progresses towards its more concentrated structure, the Solar System similarly progresses.

So understood, Evolution becomes not one in principle only, but one in fact. There are not many metamorphoses similarly carried on, but there is a single metamorphosis universally progressing, wherever the reverse metamorphosis has not set in. In any locality, great or small, where the occupying matter acquires an appreciable individuality, or distinguishableness from other matter, there Evolution goes on; or rather, the acquirement of this appreciable individuality is the commencement of Evolution. And this holds regardless of the size of the aggregate, and regardless of its inclusion in other aggregates.

§189. After making them, we saw that the inductions which, taken together, establish the law of Evolution, do not, so long as they remain inductions, form that whole rightly named Philosophy; nor does even the foregoing, from agreement into identity passage of these inductions suffice to produce the unity sought. For, as was pointed out at the time, to unify the truths thus reached with other truths, they must be deduced from the Persistence of Force. Our next step, therefore, was to show why, Force being persistent, the transformation which Evolution shows us necessarily results.

The first conclusion was, that any finite homogeneous aggregate must lose its homogeneity, through the unequal exposures of its parts to incident forces, and that the imperfectly homogeneous must lapse into the decidedly non-homogeneous. It was pointed out that the production of diversities of structure by diverse forces, and forces acting under diverse conditions, has been illustrated in astronomic evolution; and that a like connexion of cause and effect is seen in the large and small modifications undergone by our globe. The early changes of organic germs supplied further evidence that unlikenesses of structure follow unlikenesses of relations to surrounding agencies -- evidence enforced by the tendency of the differently-placed members of each species to diverge into varieties. And we found that the contrasts, political and industrial, which arise between the parts of societies, serve to illustrate the same principle. The instability of the relatively homogeneous thus everywhere exemplified, we saw also holds in each of the distinguishable parts into which any whole lapses; and that so the less heterogeneous tends continually to become more heterogeneous.

A further step in the inquiry disclosed a secondary cause of increasing multiformity. Every differentiated part is not simply a seat of further differentiations, but also a parent of further differentiations; since in growing unlike other parts, it becomes a centre of unlike reactions on incident forces, and by so adding to the diversity of forces at work, adds to the diversity of effects produced. This multiplication of effects proved to be similarly traceable throughout all Nature -- in the actions and reactions that go on throughout the Solar System, in the never-ceasing geologic complications, in the involved changes produced in organisms by new influences, in the many thoughts and feelings generated by single impressions, and in the ever-ramifying results of each additional agency brought to bear on a society. To which was joined the corollary that the multiplication of effects advances in a geometrical progression along with advancing heterogeneity.

Completely to interpret the structural changes constituting Evolution, there remained to assign a reason for that increasingly-distinct demarcation of parts, which accompanies the production of differences among parts. This reason we discovered to be the segregation of mixed units under the action of forces capable of moving them. We saw that when unlike incident forces have made the parts of an aggregate unlike in the natures of their component units, there necessarily arises a tendency to separation of the dissimilar units from one another, and to a clustering of those units which are similar. This cause of the definiteness of the local integrations which accompany local differentiations, turned out to be likewise exemplified by all kinds of Evolution -- by the formation of celestial bodies, by the moulding of the Earth's crust, by organic modifications, by the establishment of mental distinctions, by the genesis of social divisions.

At length, to the query whether these processes have any limit, there came the answer that they must end in equilibrium. That continual division and subdivision of forces which changes the uniform into the multiform and the multiform into the more multiform, is a process by which forces are perpetually dissipated; and dissipation of them, continuing as long as there remain any forces unbalanced by opposing forces, must end in rest. It was shown that when, as happens in aggregates of various orders, many movements go on together, the earlier dispersion of the smaller and more resisted movements, establishes moving equilibria of different kinds: forming transitional stages on the way to complete equilibrium. And further inquiry made it apparent that for the same reason, these moving equilibria have certain self-conserving powers; shown in the neutralization of perturbations, and in the adjustment to new conditions. This general principle of equilibration, like the preceding general principles, was traced throughout all forms of Evolution -- astronomic, geologic, biologic, mental, and social. And our concluding inference was, that the penultimate stage of equilibration in the organic world, in which the extremest multiformity and most complex moving equilibrium are established, must be one implying the highest state of humanity.

But the fact which here chiefly concerts us, is that each of these laws of the re-distribution of Matter and Motion, was found to be a derivative law-a law deducible from the fundamental law. The Persistence of Force being granted, there follow as inevitable inferences "The Instability of the Homogeneous" and "The Multiplication of Effects;" while "Segregation" and "Equilibration" also become corollaries. And on thus discovering that the processes of change grouped under these titles are so many different aspects of one transformation, determined by an ultimate necessity we arrive at a complete unification of them -- a synthesis in which Evolution in general and in detail becomes known as an implication of the law that transcends proof. Moreover, in becoming thus unified with one another the complex truths of Evolution become simultaneously unified with those simpler truths shown to have a like origin -- the equivalence of transformed forces, the movement of every mass and molecule along its line of least resistance, and the limitation of its motion by rhythm. Which further unification brings us to a conception of the entire plexus of changes presented by each concrete phenomenon, and by the aggregate of concrete phenomena, as a manifestation of one fundamental fact -- a fact shown alike in the total change and in all the separate changes composing it.

§190. Finally we turned to contemplate, as exhibited throughout Nature, that process of Dissolution which forms the complement of Evolution, and which, at some time or other, undoes what Evolution has done.

Quickly following the arrest of Evolution in aggregates that are unstable, and following it at periods often long delayed but reached at last in the stable aggregates around us, we saw that even to the vast aggregate of which all these are parts even to the Earth as a whole -- Dissolution must eventually come. Nay we even saw grounds for the belief that local assemblages of those far vaster masses. we know as stars will eventually be dissipated: the question remaining unanswered whether our Sidereal System as a whole may not at a time beyond the reach of finite imagination share the same fate. While inferring that in many parts of the visible universe dissolution is following evolution, and that throughout these regions evolution will presently recommence, the question whether there is an alteration of evolution and dissolution in the totality of things is one which must be left unanswered as beyond the reach of human intelligence.

If, however, we lean to the belief that what happens to the parts will eventually happen to the whole, we are led to entertain the conception of Evolutions that have filled an immeasurable past and Evolutions that will fill an immeasurable future. We can no longer contemplate the visible creation as having a definite beginning or end, or as being isolated. It becomes unified with all existence before and after; and the Force which the Universe presents, falls into the same category with its Space and Time, as admitting of no limitation in thought.

§191. This conception is congruous with the conclusion reached in Part I, where we dealt with the relation between the Knowable and the Unknowable.

It was there shown by analysis of both religious and scientific ideas, that while knowledge of the Cause which produces effects on consciousness is impossible, the existence of a Cause for these effects is a datum of consciousness. Belief in a Power which transcends knowledge is that fundamental element in Religion which survives all its changes of form. This inexpugnable belief proved to be likewise that on which all exact Science is based. And this is also the implication to which we are now led back by our completed synthesis. The recognition of a persistent Force, ever changing its manifestations but unchanged in quantity throughout all past time and all future time, is that which we find alone makes possible each concrete interpretation, and at last unifies all concrete interpretations.

Towards some conclusion of this order, inquiry scientific, metaphysical, and theological, has been, and still is, manifestly advancing. The coalescence of polytheistic conceptions into the monotheistic conception, and the reduction of the monotheistic conception to a more and more general form, in which personal superintendence becomes merged in universal immanence, clearly shows this advance. It is equally shown in the fading away of old theories about "essences," "potentialities," "occult virtues," etc.; in the abandonment of such doctrines as those of "Platonic Ideas," "Pre-established Harmonies," and the like; and in the tendency towards the identification of Being as present in consciousness, with Being as otherwise conditioned beyond consciousness. Still more conspicuous is it in the progress of Science, which, from the beginning, has been grouping.isolated facts under laws, uniting special laws under more general laws, and so reaching on to laws of higher and higher generality; until the conception of universal laws has become familiar to it.

Unification being thus the characteristic of developing thought of all kinds, and eventual arrival at unity being fairly inferable, there arises yet a further support to our conclusion. Since, unless there is some other and higher unity, the unity we have reached must be that towards which developing thought tends.

Let no one suppose that any such implied degree of trustworthiness is alleged of the various minor propositions brought in illustration of the general argument. Such an assumption would be so manifestly absurd, that it seems scarcely needful to disclaim it. But the truth of the doctrine as a whole, is unaffected by errors in the details of its presentation. If it can be shown that the Persistence of Force is not a datum of consciousness; or if it can be shown that the several laws of force above specified are not corollaries from it; or if it can be shown that, given these laws, the re-distribution of Matter and Motion does not necessarily proceed as described; then, indeed, it will be shown that the theory of Evolution has not the high warrant claimed for it. But nothing short of this can invalidate the general conclusions lived at.

§193. If these conclusions be accepted -- if it be agreed that the phenomena going on everywhere are parts of the general process of Evolution, save where they are parts of the reverse process of Dissolution; then we may infer that all phenomena receive their complete interpretation only when recognized as parts of these processes. Whence it follows that the limit towards which Knowledge advances can be reached only when the formulae of these processes are so applied as to yield interpretations of phenomena in general. But this is an ideal which the real must ever fall short of.

For true though it may be that all phenomenal changes are direct or indirect results of the persistence of force, the proof that they are such can never be more than partially given. Scientific progress is progress in that adjustment of thought to things which we saw is going on, and must continue to go on, but which can never arrive at anything like perfection. Still, though Science can never be reduced to this form, and though only at a far distant time can it be brought anywhere near it, a good deal may even now be done in the way of approximation.

Of course, what may now be done cannot be done by any single individual. No one can possess that encyclopaedic information required for rightly organizing even the truths already established. Nevertheless, as all organization, beginning in faint and blurred outlines, is completed by successive modifications and additions, advantage may accrue from an attempt, however rude, to reduce the facts now accumulated -- or rather certain classes of them -- to something like co-ordination. Such must be the plea for the several volumes which are to succeed this; dealing with the respective divisions of what we distinguished at the outset as Special Philosophy.

§194. A few closing words must be said, conceding the general bearings of the doctrines that are now to be further developed.

Though it is impossible to prevent misrepresentations, especially when the questions involved are of a kind that excite so much animus, yet to guard against them as far as may be, it will be well to make a succinct and emphatic restatement of the Philosophico-Religious doctrine which pervades the foregoing pages.

Over and over again it has been shown in various ways, that the deepest truths we can reach, are simply statements of the widest uniformities in our experiences of the relations of Matter, Motion, and Force; and that Matter, Motion, and Force are but symbols of the Unknown Reality. A Power of which the nature remains for ever inconceivable, and to which no limits in Time or Space can be imagined, works in us certain effects. These effects have certain likenesses of kind, the most general of which we class together under the names of Matter, Motion, and Force; and between these effects there are likenesses of connexion, the most constant of which we class as laws of the highest certainty. Analysis reduces these several kinds of effect to one kind of effect; and these several kinds of uniformity to one kind of uniformity. And the highest achievement of Science is the interpretation of all orders of phenomena, as differently-conditioned manifestations of this one kind of effect, under differently-conditioned modes of this one kind of uniformity. But when Science has done this, it has done nothing more than systematize our experiences, and has in no degree extended the limits of our experiences. We can say no more than before, whether the uniformities are as absolutely necessary as they have become to our thought relatively necessary. The utmost possibility for us is an interpretation of the process of things as it presents itself to our limited consciousness; but how this process is related to the actual process we are unable to conceive, much less to know. Similarly, it must be remembered that while the connexion between the phenomenal order and the ontological order is for ever inscrutable; so is the connexion between the conditioned forms of being and the unconditioned form of being for ever inscrutable. The interpretation of all phenomena in terms of Matter, Motion, and Force, is nothing more than the reduction of our complex symbols of thought, to the simplest symbols; and when the equation has been brought to its lowest terms the symbols remain symbols still. Hence the reasonings contained in the foregoing pages, afford no support to either of the antagonist hypotheses respecting the ultimate nature of things. As before implied, their implications are no more materialistic than they are spiritualistic; and no more spiritualistic than they are materialistic. The establishment of correlation and equivalence between the forces of the outer and the inner worlds, serves to assimilate either to the other, according as we set out with one or other term. But he who rightly interprets the doctrine contained in this work, will see that neither of these terms can be taken as ultimate. He will see that though the relation of subject and object renders necessary to us these antithetical conceptions of Spirit and Matter; the one is no less than the other to be regarded as but a sign of the Unknown Reality which underlies both.