Chapter 14   The Law of Evolution

§107. Deduction has now to be verified by induction. Thus far the argument has been that all sensible existences must, in some way or other and at some time or other, reach their concrete shapes through processes of concentration; and the facts named have been named merely to clarify the perception of this necessity. But we have not arrived at that unified knowledge constituting Philosophy, until we have seen how existences of all orders do exhibit a progressive integration of Matter and accompanying loss of Motion. Tracing, so far as we may by observation and inference, the objects dealt with by the Astronomer and the Geologist, as well as those which Biology, Psychology, and Sociology treat of, we have to consider what direct proof there is that the Cosmos, in general and in detail, conforms to this law.

Throughout the classes of facts successively contemplated, attention will be directed not so much to the truth that every aggregate has undergone, or is undergoing, integration, as to the further truth that in every more or less separate part of every aggregate, integration has been, or is, in progress. Instead of simple wholes and wholes of which the complexity has been ignored, we have now to deal with wholes as they actually exist -- mostly made up of many members combined in many ways. And in them we shall have to trace the transformation under several forms -- a passage of the total mass from a more diffused to a more consolidated state; a concurrent similar passage in every portion of it that comes to have a distinguishable individuality; and a simultaneous increase of combination among such individualized portions.

§108. Our Sidereal System by its general form, by its clusters of stars of various degrees of closeness, and by its nebulae in all stages of condensation, gives grounds for suspecting that, generally and locally, concentration is going on. Assume that its matter has been, and still is being, drawn together by gravitation, and we have an explanation of its leading traits of structure -- from its solidified masses up to its collections of attenuated flocculi barely discernible by the most powerful telescopes, from its double stars up to such complex aggregates as the nubeculae. Without dwelling on this evidence, however, let us pass to the case of the Solar System.

The belief, so variously supported, that this has had a nebular genesis, is the belief that it has arisen by the integration of matter and concomitant loss of motion. Evolution, under its primary aspect, is illustrated most simply and clearly by this passage of the Solar System from a diffused incoherent state to a consolidated coherent state. While, according to the nebular hypothesis, there has been going on a gradual concentration of the Solar System as an aggregate, there has been a simultaneous concentration of each partially-independent member. The changes of every planet in passing through its stages of nebulous ring, gaseous spheroid, liquid spheroid, and spheroid externally solidified, have in essentials -- dissipation of motion and aggregation of matter -- paralleled the changes gone through by the general mass; and those of every satellite have done the like. Moreover, at the same time that the matter of the whole, as well as the matter of each partially-independent part, has been thus integrating, there has been the further integration implied by increasing combination among the parts. The satellites of each planet are linked with their primary into a balanced cluster, while the planets and their satellites form with the Sun, a compound group of which the members are more strongly bound together than were the far-spread portions of the nebulous medium out of which they arose.

Even apart from the nebular hypothesis, the Solar System furnishes facts having a like general meaning. Not to make much of the meteoric matter perpetually added to the Earth, and probably to the other planets, as well as, in larger quantities, to the Sun, it will suffice to name two generally-admitted instances. The one is the retardation of comets by the ethereal medium, and the inferred retardation of planets -- a process which must in time, as Lord Kelvin argues, bring comets, and eventually planets, into the Sun. The other is the Sun's still-continued loss of motion in the shape of radiated heat; accompanying the still-continued integration of his mass.

§109. To astronomic evolution we pass without break to the evolution which, for convenience, we separate as geologic. The history of the Earth, as traced out from the structure of its crust, carries us back to that molten state which the nebular hypothesis implies; and, as before pointed out (§69), the changes called igneous are accompaniments of the advancing consolidation of the Earth's substance and loss of its contained motion. The general effects and the local effects must be briefly exemplified.

Leaving behind the time when the more volatile elements now existing as solids were kept by the high temperature in a gaseous form, we may begin with the fact that until the Earth's surface had cooled far below red heat, the mass of water at present covering three-fifths of it, must have existed as vapour. This enormous volume of unintegrated liquid became integrated as fast as dissipation of the Earth's contained motion allowed; leaving, at length, a comparatively small portion uncondensed, which would condense but for the unceasing absorption of molecular motion from the Sun. In the formation of the Earth's crust we have a similar change similarly caused. The passage from a thin solid film, everywhere fissured and movable on the subjacent molten matter, to a crust so thick and strong as to be but now and then very slightly dislocated by disturbing forces, illustrates the process. And while, in this superficial solidification, we see under one form how concentration accompanies loss of contained motion, we see it under another form in that diminution of the Earth's bulk implied by superficial corrugation.

Local or secondary integrations have advanced along with this general integration. A molten spheroid merely skinned over with solid matter, could have presented nothing beyond small patches of land and water. Differences of elevation great enough to form islands of considerable size, imply a crust of some rigidity; and only as the crust grew thick could the land be united into continents divided by oceans. So, too, with the more striking elevations. The collapse of a thin layer round its cooling and contracting contents, would throw it into low ridges. The crust must have acquired a relatively great depth and strength before extensive mountain systems of Vast elevation became possible: continued integration of it made possible great local integrations. In sedimentary changes a like progress is inferable. Denudation acting on the small surfaces exposed during early stages, would produce but small local deposits. The collection of detritus into strata of great extent, and the union of such strata into extensive "systems," imply wide surfaces of land and water, as well as subsidences great in both area and depth; so that integrations of this order must have grown more pronounced as the Earth's crust thickened.

§110. Already we have recognized the fact that the evolution of an organism is primarily the formation of an aggregate, by the continued incorporation of matter previously spread through a wider space. Every plant grows by taking into itself elements that were before diffused, and every animal grows by re-concentrating these elements previously dispersed in surrounding plants or other animals. Here it will be proper to complete the conception by pointing out that the early history of a plant or animal, still more clearly than its later history, shows us this fundamental process. For the microscopic germ of each organism undergoes, for a long time, no other change than that implied by absorption of nutriment. Cells embedded in the stroma of an ovarium, become ova by little else than continued growth at the expense of adjacent materials. And when, after fertilization, a more active evolution commences, its most conspicuous trait is the drawing-in, to a germinal centre, of the substance which the ovum contains.

Now, however, our attention must be directed mainly to the secondary integrations which accompany the primary integration. We have to observe how, along with the formation of a larger mass of matter, there goes on a gathering together and consolidation of this matter into parts, as well as a closer combination of the parts. In the mammalian embryo the heart, at first a long pulsating blood-vessel, by-and-by twists upon itself and integrates. The bile-cells constituting the rudimentary liver, do not simply become different from the wall of the intestine in which they at first lie, but, while accumulating, they diverge from it and consolidate into an organ. The anterior portion of the cerebrospinal axis, at first continuous with. the rest, and not markedly distinguished from it, undergoes a union of its rapidly-growing parts; and at the same time the resulting head folds into a mass marked off from the spine. The like process, variously exhibited in other organs, is meanwhile exhibited by the body as a whole; which becomes integrated somewhat in the same way that an outspread handkerchief and its contents become integrated when its edges are drawn in and fastened to make a bundle. Kindred changes go on after birth, and continue even up to old age. In man, that solidification of the bony framework which, during childhood, is seen in the coalescence of portions of the same bone ossified from different centres, is afterwards seen in the coalescence of bones that were originally distinct. The appendages of the vertebrae join with the vertebral centres to which they belong: a change not completed until towards thirty. At the same time the epiphyses, formed separately from the main bodies of their respective bones, have their cartilaginous connexions turned into osseous ones -- are fused to the masses beneath them. The component vertebra of the sacrum, which remain separate till about the sixteenth year, then begin to unite; and in ten or a dozen years more their union is complete. Still later occurs the junction of the coccygeal vertebra; and there are some other bony unions which remain unfinished unless advanced age is reached. To which add that the increase of density, going on throughout the tissues at large during life, is the formation of a more fully integrated substance.

The species of change thus illustrated, may be traced in all animals. That mode of it which consists in the union of similar parts originally separate, has been described by Milne-Edwards and others, as exhibited in various Invertebrata; though it does not seem to have been included by them as an essential trait of organic development. We shall, however, see that local integration is an all-important part of this process, when we find it not only in the successive stages passed through by every embryo, but also in ascending from the lower creatures to the higher. As manifested in either way, it goes on both longitudinally and transversely; under which different forms we may conveniently consider it. Of longitudinal integration, the sub-kingdom Annulosa * <* I adhere to this name though of late years the two divisions Annelida and Arthropoda have usurped its place. Their kinship as lower and higher is admitted, and the name is descriptive of both; for the being formed of rings is their most conspicuous structural trait.> supplies abundant examples. Its lower members, such as worms and next to them myriapods, are mostly characterized by the great numbers of their segments; reaching in some cases to several hundreds. But in the higher divisions -- crustaceans, insects, and arachnids -- this number is reduced to twenty-two, thirteen, or even fewer; while, accompanying the reduction, there is a shortening or integration of the whole body, reaching its extreme in the crab and the spider. The significance of these contrasts, as bearing on the doctrine of Evolution, will be clear when it is observed that they are parallel to those which arise during the development of individual annulose animals. The head and thorax of a lobster form one compact box, made by the union of a number of segments which in the embryo were separable. Similarly, the butterfly shows us segments so much more closely united than they were in the caterpillar, as to be, some of them, no longer distinguishable from one another. The Vertebrata again, throughout their successively higher classes, furnish like instances of longitudinal union. In most fishes, and in limbless reptiles, none of the vertebra coalesce. In most mammals and in birds, a variable number of vertebra become fused to form the sacrum; and in the higher apes and in man, the caudal vertebra also lose their separate individualities in a single oscoccygis. That which we may distinguish as transverse integration, is well illustrated among the Annulosa in the development of the nervous system. Leaving out those most degraded forms which do not present distinct ganglia, we find that the lower annulose animals, in common with the larva of the higher, are severally characterized by a double chain of ganglia running from end to end of the body; while in the more perfectly-formed annulose animals, the two chains unite into a single chain. Mr. Newport has described the course of this concentration in insects, and by Rathke it has been traced in crustaceans. During the early stages of the common cray-fish, there is a pair of ganglia to each ring. Of the fourteen pairs belonging to the head and thorax, the three pairs in advance of the mouth consolidate to form the cephalic ganglion or brain. Meanwhile, of the remainder, the first six pairs severally unite in the median line, while the rest remain more or less separate. Of these six double ganglia thus formed, the anterior four coalesce into one mass; the remaining two coalesce into another mass, and then these two masses coalesce. Here longitudinal and transverse integration go on simultaneously and in the highest crustaceans they are both carried still further. The Vertebrata exhibit transverse integration in the development of the generative system. The lowest mammals -- the Monotremata -- in common with birds, to which they are in many respects allied, have oviducts which towards their lower extremities are dilated into cavities, each imperfectly performing the function of a uterus. "In the Marsupialia there is a closer approximation of the two lateral sets of organs on the median line: for the oviducts converge towards one another and meet (without coalescing) on the median line; so that their uterine dilatations are in contact with each other, forming a true 'double uterus.'... As we ascend the series of 'placental' mammals, we find the lateral coalescence becoming more and complete.... In many of the Rodentia the uterus still remains completely divided into two lateral halves; whilst in others these coalesce at their lower portions, forming a rudiment of the true 'body' of the uterus in the human subject. This part increases at the expense of the lateral 'cornua' in the higher herbivora and carnivora; but even in the lower quadrumana the uterus is somewhat cleft at its summit."* <* Carpenter's Prin. of Comp. Phys., p. 617.>

Under the head of organic integrations, there remain to be noted another class of illustrations. Whether the Annulosa referred to above are or are not originally compound animals, it is unquestionable that there are compound animals among other classes of invertebrates: integration is displayed not within the limits of an individual only but by the union of many individuals. The Salpidae are composite creatures having the shape of chains joined more or less permanently; and Pyrosoma shows us a large number united into a cylinder. Moreover in the Botryllidae the merging of the individualities goes so far that instead of having separate skins they are enclosed within a common skin. Among the Caeienterata integration produces half-fused colonies of types unlike these. There are the branched Hydrozoa in which many individuals form an aggregate in such a way as to have a common system of nutrition, while some of them undertake special functions; and much the same may be said of those compound Actinozoa which are imbedded in the calcareous frameworks we know as corals. And then in certain pelagic types, grouped as Siphonophora, the united individuals, in some cases alike, are in other cases severally transformed in adaptation to various functions; so that the component individuals, assuming the characters of different organs, become practically combined into a single organism.

From this kind of integration we pass to a kind in which the individuals are not physically united but simply associated -- are integrated only by their mutual dependence. We may set down two kinds -- those which occur within the same species, and those which occur between members of different species. More or less of the gregarious tendency is common among animals; and when it is marked, there is, in addition to simple aggregation, some degree of combination. Creatures that hunt in packs, or that have sentinels, or that are governed by leaders, form bodies partially united by co-operation. Among polygamous mammals and birds this mutual dependence is closer; and the social insects show us still more consolidated assemblages: some of them having their members so united that they cannot live independently How organisms in their totality are mutually dependent, and in that sense integrated, we shall see on remembering -- first, that while all animals live directly or indirectly on plants, plants utilize the carbon dioxide excreted by animals; second, that among animals the flesh-eaters cannot exist without the plant-eaters; third, that a large proportion of plants can continue their respective races only by the help of insects. Without detailing the more complex connexions, which Mr. Darwin has so beautifully illustrated, it will suffice to say that the Flora and Fauna in each habitat, constitute an aggregate so far integrated that many of its species die out if placed amid the plants and animals of another habitat. And this integration, too, increases as organic evolution advances.

§111. The phenomena set down in the foregoing paragraph introduce us to others of a higher order, with which they ought, in strictness, to be grouped-phenomena which we may term super-organic. Inorganic bodies present us with certain facts. Additional facts, mostly of a more involved kind, are presented by organic bodies. There remain yet further facts, not presented by any organic body taken singly, but which result from the actions of aggregated organic bodes. Though phenomena of this order are, as we see, foreshadowed among inferior organisms, they become so conspicuous in mankind as socially united, that practically we may consider them to commence here.

In the social organism integrative changes are abundantly exemplified. Uncivilized societies display them when wandering families, such as those of Bushmen, join into tribes of considerable size. A further progress in mass results from the subjugation of weak tribes by strong ones; and in the subordination of their respective chiefs to the conquering chief. Such combinations which, among aboriginal races, are continually being formed and continually broken up, become, among superior races, relatively permanent. If we trace the stages through which our own society, or any adjacent one, has passed, we see this unification from time to time repeated on a larger scale and gaining in stability The consequent establishment of groups of vassals bound to their respective lords; the subsequent subjection of groups of inferior nobles to dukes or earls; and the still later growth of the kingly power over dukes and earls; are so many instances of increasing consolidation. This process slowly completes itself by destroying the original lines of demarcation. And of the European nations it may be further remarked, that in the tendency to form alliances, in the restraining influences exercised by governments over one another, in the system of settling international arrangements by congresses, as well as in the weakening of commercial barriers and the increasing facilities of communication, we see the beginnings of a European federation -- a still larger integration that any now established.

But it is not only in these external unions of groups with groups, and of the compound groups with one another, that the general law is exemplified. It is exemplified also in unions which take place internally, as the groups become better organized. There are two orders of these, broadly distinguishable as regulative and operative. A civilized society is made unlike a savage tribe by the establishment of regulative classes-governmental, administrative, military, ecclesiastical, legal, etc., which, while they severally have their bonds of union, constituting them sub-classes, are also held together as a general class by a certain community of privileges, of blood, of education, of intercourse. In some societies, fully developed after their particular types, this consolidation into castes, and this union among the upper castes by separation from the lower eventually grow very decided: to be afterwards rendered less decided, only in cases of social metamorphosis caused by the industrial régime. The integrations seen throughout the operative or industrial organization, later in origin, are not merely of this indirect kind, but they are also direct -- they show us physical approach. We have integrations consequent on the growths of adjacent parts performing like functions; as, for instance, the junction of Manchester with its calico-weaving suburbs. We have other integrations which arise when, out of several places producing a particular commodity, one gaining more and more of the business, draws to it masters and workers, and leaves the other places to dwindle; as witness the growth of the Yorkshire cloth-districts at the expense of those in the West of England; or the absorption by Staffordshire of the pottery-manufacture, and the consequent decay of establishments at Derby and elsewhere. We have those more special integrations that arise within the same city; whence result the concentration of corn-merchants about Mark Lane, of civil engineers in Great George Street, of bankers in the centre of the city. Industrial integrations which consist, not in the approximation or fusion of parts, but in the establishment of centres of connexion, are shown in the Bankers' clearing-house and the Railway clearing-house. While of yet another species are those unions which bring into relation dispersed citizens who are occupied in like ways; as traders are brought by the Exchange, and as are professional men by institutes like those of Civil Engineers, Architects, etc.

These seem to be the last of our instances. Having followed up the general law to social aggregates, there apparently remain no other aggregates to which it can apply. This, however, is not true. Among what were above distinguished as super-organic phenomena, there are sundry further groups of remarkable illustrations. Though evolutions of the various products of social activities cannot be said directly to exemplify the integration of matter and dissipation of motion, yet they exemplify it indirectly. For the progress of Language, of Science, and of the Arts, industrial and aesthetic, is an objective register of subjective changes. Alterations of structure in human beings, and concomitant alterations of structure in aggregates of human beings, jointly produce corresponding alterations of structure in all those things which humanity creates. As in the changed impress on the wax, we read a change in the seal; so in the integrations of advancing Language, Science, and Art, we see reflected certain integrations of advancing human structure, individual and social. A section must be devoted to each group.

§112. Among uncivilized races, the many-syllabled names of not uncommon objects, as well as the descriptive character of proper names, show that the words used for the less-familiar things are formed by uniting the words used for the more-familiar things. This process of composition is sometimes found in its incipient stage -- a stage in which the component words are temporarily joined to signify some unnamed object, and, from lack of frequent use, do not permanently cohere. But in most inferior languages, the process of "agglutination" has gone far enough to produce some stability in the compound words: there is a manifest integration. How small is this integration, however, in comparison with that reached in well-developed languages, is shown both by the great length of the compound words used for common things and acts, and by the separableness of their elements. Certain North-American tongues illustrate this very well. In a Ricaree vocabulary extending to fifty names of common objects, which in English are nearly all expressed by single syllables, there is not one monosyllabic word. Things so familiar to these hunting tribes as dog and bow, are, in the Pawnee language, ashakish and teeragish; the hand and the eyes are respectively iksheeree and keereekoo. for day the term is shakoorooeeshairet, and for devil it is tsaheekshkakooraiwah. while the numerals are composed of from two syllables up to five, and in Ricaree up to seven. That the great length of these familiar words implies low development, and that in the formation of higher languages out of lower there is a gradual integration, which reduces the polysyllables to dissyllables and monosyllables, is an inference confirmed by the history of our own language. Anglo-Saxon steorra has been in course of time consolidated into English star, mona into moon, and nama into name. The transition through semi-Saxon is clearly traceable. Sunu became in semi-Saxon sune, and in English son; the final e of sune being an evanescent form of the original u. The change from the Anglo-Saxon plural, formed by the distinct syllable as, to our plural formed by the appended consonant s, shows the same thing: smithas in becoming smiths, and endas in becoming ends, illustrate progressive coalescence. So, too does the disappearance of the terminal an in the infinitive mood of verbs; as shown in the transition from the Anglo-Saxon cuman to the semi-Saxon cumme, and to the English come. Moreover the process has been slowly going on, even since what we distinguish as English was formed. In Elizabeth's time, verbs were still frequently pluralized by the addition of en -- we tell was we tellen; and in some places this form of speech may even now be heard. In like manner the terminal ed of the past tense, has united with the word it modifies. Burn-ed has in pronunciation become burnt; and even in writing, the terminal t has in some cases taken the place of the ed. Only where antique forms in general are adhered to, as in the church-service, is the distinctness of this inflection still maintained. Further, we see that the compound vowels have been in many cases fused into single vowels. That in bread the e and a were originally both sounded, is proved by the fact that they are still so sounded in parts where old habits linger. We, however have contracted the pronunciation into bred; and we have made like changes in many other common words. Lastly, let it be noted that where the repetition is greatest, the process is carried furthest; as instance the contraction of lord (originally hlaford) into lud in the mouths of barristers; and, still better, the coalescence of God be with you into Good bye.

Besides thus exhibiting the integrative process, Language equally exhibits it throughout all grammatical development. The lowest kinds of human speech, having merely nouns and verbs without inflections, permit no such close union of the elements of a proposition as results when their relations are marked either by inflections or by connective words. Such speech is what we significantly call "incoherent." To a considerable extent, incoherence is seen in the Chinese language. "If, instead of saying I go to London, figs come from Turkey, the sun shines through the air, we said, I go end London, figs come origin Turkey, the sun shines passage air, we should discourse after the manner of the Chinese." From this "aptotic" form, there is a transition, by coalescence, to a form in which the connexions of words are expressed by joining with them certain inflectional words. "In Languages like the Chinese," remarks Dr. Latham, "the separate words most in use to express relation may become adjuncts or annexes." To this he adds the fact that "the numerous inflexional languages fall into two classes. In one, the inflexions have no appearance of having been separate words. In the other, their origin as separate words is demonstrable." From which the inference drawn is, that the "aptotic" languages, by the more and more constant use of adjuncts, gave rise to the "agglutinate" languages, or those in which the original separateness of the inflexional parts can be traced; and that out of these, by further use, arose the "amalgamate" languages, or those in which the original separateness of the inflexional parts can no longer be traced. Strongly corroborative of this inference is the fact that, by such a process, there have grown out of the amalgamate languages, the "anaptotic" languages, of which our own is the best example -- languages in which, by further consolidation, inflexions have almost disappeared, while, to express the verbal relations, new kinds of words have been developed. When we see the Anglo-Saxon inflexions gradually lost by contraction during the development of English, and, though to a less degree, the Latin inflexions dwindling away during the development of French, we cannot deny that grammatical structure is modified by integration; and seeing how clearly the earlier stages of grammatical structure are explained by it, we must conclude that it has been going on from the first.

In proportion to the degree of this integration, is the extent to which integration of another order is carried. Aptotic languages are, as already pointed out, necessarily incoherent -- the elements of a proposition cannot be completely tied into a whole. But as fast as coalescence produces inflected words, it becomes possible to unite them into sentences of which the parts are so mutually dependent that no considerable change can be made without destroying the meaning. Yet a further stage in this process may be noted. After the development of those grammatical forms which make definite statements possible, we do not at first find them used to express anything beyond statements of a simple kind. A single subject with a single predicate, accompanied by but few qualifying terms, are usually all. If we compare, for instance, the Hebrew scriptures with writings of modern times, a marked difference of aggregation among the groups of words, is visible. In the number of subordinate propositions which accompany the principal one; in the various complements to subjects and predicates; and in the numerous qualifying clauses -- all of them united into one complex whole -- many sentences in modern compositions exhibit a degree of integration not to be found in ancient ones.

§113. The history of Science presents facts of the same meaning at every step. Indeed the integration of groups of like entities and like relations, constitutes the most conspicuous part of scientific progress. A glance at the classificatory sciences, shows that the confused incoherent aggregations which the vulgar make of natural objects, are gradually rendered complete and compact, and bound up into groups within groups. While, instead of considering all marine creatures as fish, shell-fish, and jellyfish, Zoology establishes among them subdivisions under the heads Vertebrata, Annulosa, Mollusca, Coelenterata, etc.; and while, in place of the wide and vague assemblage popularly described as "creeping things," it makes the specific classes Annelida, Myiiapoda, Insecta, Arachnida; it simultaneously gives to these an increasing consolidation. The several species, genera, and orders of which each consists, are arranged according to their affinities and tied together under common definitions; at the same time that, by extended observation and rigorous criticism, the previously unknown and undetermined forms are integrated with their respective congeners. Nor is the process less clearly displayed in those sciences which have for their subject-matter, not classified objects but classified relations. Under one of its chief aspects, scientific advance is the advance of generalization; and generalizing is uniting into groups all like co-existences and sequences among phenomena. The colligation of many concrete relations into a generalization of the lowest order, exemplifies this process in its simplest form; and it is again exemplified in a more complex form by the colligation of these lowest generalizations into higher ones, and these into still higher ones. Year by year connexions are established among orders of phenomena that appear unallied; and these connexions, multiplying and strengthening, gradually bring the seemingly unallied orders under a common bond. When, for example, Humboldt quotes the observation of the Swiss -- "it is going to rain because we hear the murmur of the torrents nearer," -- when he recognizes the kinship between this and an observation of his own, that the cataracts of the Orinoco are heard at a greater distance by night than by day -- when he notes the analogy between these facts and the fact that the unusual visibility of remote objects is also an indication of coming rain -- and when he points out that the common cause of these variations is the smaller hindrance offered to the passage of both light and sound, by media which are comparatively homogeneous, either in temperature or hygrometric state; he helps in bringing under one generalization certain traits of light and certain traits of sound. Experiments having shown that light and sound conform to like laws of reflection and refraction, the conclusion that they are both produced by undulations --though undulations of unlike kinds -- gains probability: there is an incipient integration of two classes of facts between which no connexion was suspected in times past. A still more decided integration has been of late taking place between the once independent sub-sciences of Electricity, Magnetism, and Light.

The process will manifestly be carried much further. Such propositions as those set forth in preceding chapters, on "The Persistence of Force," "The Transformation and Equivalence of Forces," "The Direction of Motion," and "The Rhythm of Motion," unite within single bonds phenomena belonging to all orders of existences. And if there is such a thing as that which we here understand by Philosophy, there must eventually be reached a universal integration.

§114. Nor do the industrial and aesthetic Arts fail to supply us with equally conclusive evidence. The progress from small and simple tools, to complex and large machines, is a progress in integration. Among what are classed as the mechanical powers, the advance from the lever to the wheel-and-axle is an advance from a simple agent to an agent made up of several simple ones. On comparing the wheel-and-axle, or any of the mechanical appliances used in early times with those used now, we see that in each of our machines several of the primitive machines are united. A modern apparatus for spinning or weaving, for making stockings or lace, contains not simply a lever, an inclined plane, a screw, a wheel-and-axle, joined together, but several of each -- all made into a whole. Again, in early ages, when horsepower and man-power were alone employed, the motive agent was not bound up with the tool moved; but the two have now become in many cases joined together. The firebox and boiler of a locomotive are combined with the machinery which the steam works. A much more extensive integration is seen in every factory. Here numerous complicated machines are all connected by driving shafts with the same steam-engine -- all united with it into one vast apparatus.

Contrast the mural decorations of the Egyptians and Assyrians with modern historical paintings, and there is manifest an advance in unity of composition -- in the subordination of the parts to the whole. One of these ancient frescoes is made up of figures which vary but little in conspicuousness: there are no gradations of light and shade. The same trait may be noted in the tapestries of medieval days. Representing perhaps a hunting scene, one of these contains men, horses, dogs, beasts, birds, trees, and flowers, miscellaneously dispersed: the living objects being variously occupied, and mostly with no apparent consciousness of one another's proximity. But in paintings since produced, faulty as many of them are in this respect, there is always some co-ordination -- an arrangement of attitudes, expressions, lights, and colours, such as to combine the parts into a single scene; and the success with which unity of effect is educed from variety of components, is a chief test of merit.

In music, progressive integration is displayed in more numerous ways. The simple cadence embracing but a few notes, which in the chants of savages is monotonously repeated, becomes, among civilized races, a long series of different musical phrases combined into one whole; and so complete is the integration that the melody cannot be broken off in the middle, nor shorn of its final note, without giving us a painful sense of incompleteness. When to the air, a bass, a tenor, and an alto are added; and when to the different voice-parts there is joined an accompaniment; we see integrations of another order which grow gradually more elaborate. And the process is carried a stage higher when these complex solos, concerted pieces, choruses, and orchestral effects, are combined into the vast ensemble of an oratorio or a musical drama.

Once more the Arts of literary delineation, narrative and dramatic, furnish us with illustrations. The tales of primitive times, like those with which the storytellers of the East still amuse their listeners, are made up of successive occurrences, mostly unnatural, that have no natural connexions: they are but so many separate adventures put together without necessary sequence. But in a good modern work of imagination, the events are the proper products of the characters living under given conditions; and cannot at will be changed in their order or kind, without injuring or destroying the general effect. Further, the characters themselves, which in early fictions play their respective parts without showing how their minds are modified by one another or by the events, are now presented to us as held together by complex moral relations, and as acting and reacting on one another's natures.

§115. Evolution, then, under its primary aspect, is a change from a less coherent form to a more coherent form, consequent on the dissipation of motion and integration of matter. This is the universal process through which sensible existences, individually and as a whole, pass during the ascending halves of their histories. This proves to be a character displayed in those earliest changes which the visible Universe is supposed to have undergone, and in those latest changes which we trace in societies and the products of social life. And, throughout, the unification proceeds in several ways simultaneously.

Alike during the evolution of the Solar System, of a planet, of an organism, of a nation, there is progressive aggregation. This may be shown by the increasing density of the matter already contained in it; or by the drawing into it of matter that was before separate: or by both. But in any case it implies a loss of relative motion. At the same time, the parts into which the mass has divided, severally consolidate in like manner. We see this in that formation of planets and satellites which has gone on along with the progressive concentration of the nebula that originated the Solar System; we see it in that growth of separate organs which advances, pari passu, with the growth of each organism; we see it in that rise of special industrial centres and special masses of population, which is associated with the development of each society. Always more or less of local integration accompanies the general integration. And then, beyond the increased closeness of juxtaposition among the components of the whole, and among the components of each part, there is increase of combination, producing mutual dependence of them. Dimly foreshadowed as this mutual dependence is among inorganic existences, both celestial and terrestrial, it becomes distinct among organic and super-organic existences. From the lowest living forms upwards, the degree of development is marked by the degree in which the several parts constitute a co-operative assemblage -- are integrated into a group of organs that live for and by one another. The like contrast between undeveloped and developed societies is conspicuous: there is an ever-increasing coordination of parts. And the same thing holds true of social products, as, for instance, of Science; which has become highly integrated not only in the sense that each division is made up of dependent propositions, but in the sense that the several divisions cannot carry on their respective investigations without aid from one another.

Chapter 15  The Law of Evolution (continued)

§116. Changes great in their amounts and various in their kinds, which accompany those dealt with in the last chapter, have thus far been ignored; or, if tacitly recognized, have not been avowedly recognized. Integration of each whole has been described as taking place simultaneously with integration of each of the parts into which it divides itself. But how comes the whole to divide itself into parts? This is a transformation more remarkable than the passage of the whole from an incoherent to a coherent state; and a formula which says nothing about it omits more than half the phenomena to be formulated.

This larger half of the phenomena we have now to treat. Here we are concerned with those. secondary re-distributions of matter and motion which go on along with the primary re-distribution. We saw that while in very incoherent aggregates, secondary redistributions produce but evanescent results, in aggregates that reach and maintain a certain medium state, neither very incoherent nor very coherent, results of a relatively persistent kind are produced -- structural modifications. And our next inquiry must be -- What is the universal expression for these structural modifications?

Already an implied answer has been given by the title -- Compound Evolution. Already in distinguishing as simple Evolution, that integration of matter and dissipation of motion which is unaccompanied by secondary re-distributions, it has been tacitly asserted that where secondary re-distributions occur complexity arises; the mass, instead of remaining uniform, must have become multiform. The proposition is an identical one. To say that along with the primary re-distribution there go secondary re-distributions, is to say that along with the change from a diffused to a concentrated state, there goes a change from a homogeneous state to a heterogeneous state. The components o f the mass while becoming integrated have also become differentiated.* <* The terms here used must be understood in relative senses. Since we know of no such thing as absolute diffusion or absolute concentration, the change can never be anything but a change from a more diffused to a less diffused state -- from smaller coherence to greater coherence; and, similarly, as no concrete existences present us with absolute simplicity -- as nothing is perfectly uniform -- as we nowhere find complete homogeneity, the transformation is literally always towards greater complexity or increased multiformity or further heterogeneity. This qualification the reader must bear in mind.>

This, then, is the second aspect under which we have to study Evolution. In the last chapter we contemplated existences of all orders as displaying progressive integration. In this chapter we have to contemplate them as displaying progressive differentiation.

§117. A growing variety of structure throughout our Sidereal System, is implied by the contrasts which indicate aggregation throughout it. We have nebulae that are diffused and irregular, and others that are spiral, annular, spherical. We have groups of stars the members of which are scattered, and groups concentrated in all degrees down to closely-packed globular clusters. We have these groups differing in the numbers of their members, from those containing several thousand stars to those containing but two. Among individual stars there are great contrasts, real as well as apparent, of size; and from their unlike colours, as well as from their unlike spectra, many contrasts among their physical states are inferable. Beyond which heterogeneities in detail there are general heterogeneities. Nebulae are numerous in some regions of the heavens, while in others there are only stars. Here the celestial spaces are almost void of objects, and there we see dense aggregations, nebular and stellar together.

The matter of our Solar System during its integration has become more multiform. The concentrating gaseous spheroid, dissipating its contained molecular motion, acquiring more marked unlikeness of density and temperature between interior and exterior, and leaving behind from time to time annular portions of its mass, underwent differentiations which increased in number and degree, until there was evolved the existing organized group of Sun, planets, and satellites. The heterogeneity of this is variously displayed. There are the immense contrasts between the Sun and the planets, in bulk and in weight; as well as the subordinate contrasts of like kind between one planet and another, and between the planets and their satellites. There is the further contrast between the Sun and the planets in respect of temperature; and there are indications that the planets differ from one another in their proper heats, as well as in the heats which they receive from the sun. Bearing in mind that they also differ in the inclinations of their orbits, the inclinations of their axes, in their specific gravities, and in their physical constitutions, we see how decided is the complexity wrought in the Solar System by those secondary redistributions which have accompanied the primary redistribution.

§118. Passing from illustrations, which, as assuming the nebular hypothesis, must be classed as more or less hypothetical, let us descend to evidence less open to objection.

It is now agreed among geologists that the Earth was once a molten mass. Originally, then, it was comparatively homogeneous in consistence; and, because of the circulation which takes place in heated liquids, must have been comparatively homogeneous in temperature. It must, too, have been surrounded by an atmosphere consisting partly of the elements of air and water, and partly of those various other elements which assume gaseous forms at high temperatures. Cooling by radiation must, after an immense time, have resulted in differentiating the portion most able to part with its heat; namely, the surface. A further cooling, leading to deposition of all solidifiable elements contained in the atmosphere, and then to precipitation of the water, leaving behind the air, must thus have caused a second marked differentiation; and as the condensation commenced on the coolest parts of the surface-namely, about the poles there must so have resulted the first geographical distinctions.

To these illustrations of growing heterogeneity, inferred from known laws, Geology adds an extensive series that have been inductively established. The Earth' s structure has been age after age further complicated by additions to the strata which form its crust; and it has been age after age made more various by the increasing composition of these strata; the more recent of which, formed from the detritus of the more ancient, are many of them rendered highly complex by the mixtures of materials they contain. This heterogeneity has been vastly augmented by the actions of the Earth's nucleus on its envelope; whence have resulted not only many kinds of igneous rocks, but the tilting up of sedimentary strata at all angles, the formation of faults and metallic veins, the production of endless dislocations and irregularities. Again, geologists teach us that the Earth's surface has been growing more varied in elevation -- that the most ancient mountain-systems are the smallest, and the Andes and Himalayas the most modern; while, in all probability, there have been corresponding changes in the bed of the ocean. As a consequence of this ceaseless multiplication of differences, we now find that no considerable portion of the Earth's exposed surface, is like any other portion, either in contour, in geologic structure, or in chemical composition.

There has been simultaneously going on a gradual differentiation of climates. As fast as the Earth cooled and its crust solidified, inequalities of temperature arose between those parts of its surface most exposed to the Sun and those less exposed; and thus in time there came to be the marked contrasts between regions of perpetual ice and snow regions where winter and summer alternately reign for periods varying according to the latitude, and regions where summer follows summer with scarcely an appreciable variation. Meanwhile, elevations and subsidences, recurring here and there over the Earth's crust, and producing irregular distributions of land and sea, have entailed various modifications of climate beyond those dependent on latitude; while a yet further series of such modifications has been caused by increased differences of height in the surface, which in sundry places have brought arctic, temperate, and tropical climates to within a few miles of one another. The general results are, that every extensive region has its own meteorological conditions, and that every locality in each region differs more or less from others in those conditions: as also in its structure, its contour, its soil.

Thus between our existing Earth, the phenomena of whose varied crust neither geographers, geologists, mineralogists, nor meteorologists have yet enumerated, and the molten globe out of which it was evolved, the contrast in heterogeneity is striking.

§119. The clearest, most numerous, and most varied illustrations of the advance in multiformity that accompanies the advance in integration, are furnished by living bodies. Distinguished as these are by the great quantity of their contained molecular motion, they exhibit in an extreme degree the secondary re-distributions which contained motion facilitates. The history of every plant and every animal, while it is a history of increasing bulk, is also a history of simultaneously-increasing differences among the parts. This transformation has several aspects.

The chemical composition which is almost uniform throughout the substance of a germ, vegetal or animal, gradually ceases to be uniform. The several compounds, nitrogenous and non-nitrogenous, which were homogeneously mixed, segregate by degrees, become diversely proportioned in diverse places, and produce new compounds by transformation or modification. In plants the albuminous and amylaceous matters which form the substance of the embryo, give origin here to a preponderance of chlorophyll and there to a preponderance of cellulose. Over the parts that are becoming leaf-surfaces, certain of the materials are metamorphosed into wax. In this place starch passes into one of its isomeric equivalents, sugar; and in that place into another of its isomeric equivalents, gum. By secondary change some of the cellulose is modified into wood; while some of it is modified into the allied substance which, in large masses, we call cork. And the more numerous compounds thus arising, initiate further unlikenesses by mingling in unlike ratios. The yelk, or essential part of an animal-ovum, having components which are at first evenly diffused among one another, chemically transforms itself in like manner. Its protein, its fats, its salts, become dissimilarly proportioned in different localities; and multiplication of isomeric forms leads to further mixtures and combinations that constitute minor distinctions of parts. Here a mass darkening by accumulation of hematine, presently dissolves into blood. There fatty and albuminous matters uniting, compose nerve-tissue. At this spot the nitrogenous substance takes on the character of cartilage; and at that, calcareous salts, gathering together in the cartilage, lay the foundation of bone. All these chemical differentiations slowly become more marked and more numerous.

Simultaneously arise contrasts of minute structure. Distinct tissues take the place of matter that had previously no recognizable unlikenesses of parts; and each of the tissues first produced undergoes secondary modifications, causing sub-species of tissues. The granular protoplasm of the vegetal germ, equally with that which forms the unfolding point of every shoot, gives origin to cells that are at first alike. Some of these, as they grow, flatten and unite by their edges to form the outer layer. Others lengthen, and at the same time join together in bundles to lay the foundation of woody-fibre. Before much elongating, certain of these cells show a breaking-up of the lining deposit, which, during elongation, becomes a spiral thread, or a reticulated framework, or a series of rings; and by the longitudinal union of cells so lined, vessels are formed. Meanwhile each of these differentiated tissues is re-differentiated: instance that constituting the essential part of a leaf, the upper stratum of which is composed of chlorophyll-cells remaining closely packed, while the lower stratum becomes spongy. Of the same general character are the transformations undergone by the fertilized ovum, which, at first a cluster of similar cells, quickly reaches a stage marked by dissimilarity of the cells. More frequently recurring fission of the superficial cells, a resulting smaller size of them, and subsequent union of them into an outer layer, constitute the first differentiation; and the middle area of this layer is rendered unlike the rest by still more active processes of like kind. By such modifications upon modifications, many and various, arise the classes and sub-classes of tissues which, intricately combined one with another, compose organs.

Equally conforming to the law are the changes in general shape and in the shapes of organs. All germs are at first spheres and all limbs are at first buds or mere rounded lumps. From this primordial uniformity and simplicity, there take place divergences, both of the wholes and of the leading parts, towards multiformity of contour and towards complexity of contour. Remove the compactly-folded young leaves that terminate every shoot, and the nucleus is found to be a central knob bearing lateral knobs, one of which may grow into either a leaf, a sepal, a petal, a stamen, or a carpel: all these eventually -- unlike parts being at first alike. The shoots themselves also depart from their primitive unity of form; and while each branch becomes more or less different from the rest, the whole exposed part of the plant becomes different from the imbedded part. So, too, is it with the organs of animals. One of the Arthropoda, for instance, has limbs that were originally indistinguishable from one another -- composed a homogeneous series; but by continuous divergences there have arisen among them unlikenesses of size and form, such as we see in the crab and the lobster. Vertebrate creatures equally exemplify this truth. The wings and legs of a bird are of similar shapes when they bud-out from the sides of the embryo.

Thus in every plant and animal, conspicuous secondary re-distributions accompany the primary re-distribution. A first difference between two parts; in each of these parts other differences which presently become as marked as the first; and a like multiplication of differences in geometrical progression, until there is reached that complex combination constituting the adult. This is the history of all living things whatsoever. Pursuing an idea which Harvey set afloat, it has been shown by Wolff and Von Baer, that during its development each organism passes from a state of homogeneity to a state of heterogeneity. For a generation this truth has been accepted by biologists.*
<* It was in 1852 that I became acquainted with Von Baer's expression of this general principle. The universality of law had ever been with me a postulate, carrying with it a correlative belief, tacit if not avowed, in unity of method throughout Nature. This statement that every plant and animal, originally homogeneous, becomes gradually heterogeneous, set up a co-ordination among thoughts which were previously unorganized, or but partially organized. It is true that in Social Statics (Part IV, §§12-16), published before meeting with Von Baer's formula, the development of an individual organism and the development of a social organism, are described as alike consisting in advance from simplicity to complexity, and from independent like parts to mutually-dependent unlike parts. But though admitting of extension to other super-organic phenomena, this statement was too special to admit of extension to inorganic phenomena. The great aid tendered by Von Baer's formula arose from its higher abstractness; since, only when organic transformations had been expressed in the most abstract terms, was the way opened for seeing what they had in common with inorganic transformations. The conviction that this process of change gone through by each unfolding organism, is a process gone through by all things, found its first coherent statement in an essay on "Progress: its Law and Cause" which I published in the Westminster Review for April, 1857 -- an essay with the first half of which this chapter coincides in substance, and partly in form. In that essay, how ever, as also in the first edition of this work, I fell into the error of supposing that the transformation of the homogeneous into the heterogeneous constitutes Evolution. We have seen that this is not so. It constitutes the secondary re-distribution accompanying the primary re-distribution in that Evolution which we distinguish as compound; or rather is we shill presently see, it constitutes the most conspicuous trait of this secondary re-distribution.>

§120. When we pass from individual forms of life to life at large, and ask whether the same law is seen in the ensemble of its manifestations -- whether modern plants and animals have more heterogeneous structures than ancient ones, and whether the Earth's present Flora and Fauna are more heterogeneous than the Flora and Fauna of the past, -- we find the evidence so fragmentary that nearly every conclusion is open to dispute. Three-fifths of the Earth's surface being covered by water; a great part of the exposed land being inaccessible to, or untravelled by, the geologist; the most of the remainder having been scarcely more than glanced at; and even familiar portions, as England, having been so imperfectly explored that a new series of strata has been added within these few years; it is clearly impossible to say with any certainty what creatures have, and what have not, existed at any particular period. Considering the perishable nature of many of the lower organic forms, the metamorphosis of many beds of sediment, and the gaps that occur among the rest, we shall see further reason for distrusting our deductions. On the one hand, the repeated discovery of vertebrate remains in strata previously supposed to contain none -- of reptiles where only fish were thought to exist, and of mammals where it was believed there were no creatures higher than reptiles; renders it daily more manifest how small is the value of negative evidence. On the other hand, the worthlessness of the assumption that we have found the earliest, or anything like the earliest, organic remains, is becoming equally clear. That the oldest known aqueous formations have been greatly changed by igneous action, and that still older ones have been totally transformed by it, is becoming undeniable. And the fact that sedimentary strata earlier than any we know have been melted up, being admitted, it must also be admitted that we cannot say how far back in time this destruction of sedimentary strata has been going on. For aught we know to the contrary, only the last chapters of the Earth's biological history may have come down to us.

Most inferences must thus be extremely questionable. If a progressionist argues that the earliest known vertebrate remains are those of Fishes, which are the most homogeneous of the Vertebrata; that Reptiles, which are more heterogeneous, are later; and that later still, and more heterogeneous still, are Mammals and Birds; it may be replied that the Palaeozoic deposits, not being estuary deposits, are not likely to contain the remains of terrestrial Vertebrata, which may nevertheless have existed. A like answer may be made to the argument that the vertebrate fauna of the Palaeozoic period, consisting, so far as we know, entirely of Fishes, was less heterogeneous than the modern vertebrate fauna, which includes Reptiles, Birds and Mammals, of multitudinous genera; while a uniformitarian may contend with great show of truth, that this appearance of higher and more varied forms in later geologic eras, was due to progressive immigration -- that a continent slowly upheaved from the ocean at a point remote from pre-existing continents, would necessary be peopled from them in a succession like that which our strata display. At the same time the counter-arguments may be proved equally inconclusive. When, to show that there cannot have been a continuous evolution of the more homogeneous organic forms into the more heterogeneous ones, the uniformitarian points to the breaks which occur in the succession of these forms, there is the sufficient answer that current geological changes show us why such breaks must occur, and why, by subsidences and elevations of large areas, there must be produced breaks so immense as those which divide the great geologic epochs. Or again, if the opponent of the development hypothesis cites the facts set forth by Professor Huxley in his lecture on "Persistent Types" -- if he points out that "of some two hundred known orders of plants, not one is exclusively fossil," while "among animals, there is not a single totally extinct class; and of the orders, at the outside not more than seven per cent are unrepresented in the existing creation" -- if he urges that among these some have continued from the Silurian epoch to our own day with scarcely any change and if he infers that there is a much greater average resemblance between the living forms of the past and those of the present, than consists with the hypothesis; there is still a satisfactory reply, on which in fact Prof. Huxley insists; namely, that we have evidence of a "pre-geologic era" of unknown duration. And, indeed, when we remember that the enormous subsidences of the Silurian period show the Earth's crust to have been approximately as thick then as it is now -- when we conclude that the time taken to form so thick a crust, must have been immense as compared with the time which has since elapsed -- when we assume, as we must, that during this comparatively immense time the geologic and biologic changes went on at their usual rates; it becomes manifest, not only that the palaeontological records which we find do not negative the theory of evolution, but that they are such as might rationally be looked for.

Moreover, though the evidence suffices neither for proof nor disproof, yet some of its most conspicuous facts support the belief, that the more heterogeneous organisms and groups of organisms, have been evolved from the less heterogeneous ones. The average community of type between the fossils of adjacent strata, and especially the community found between the latest tertiary fossils and creatures now existing, is one of these facts. The discovery in some modern deposits of such forms as the Pataeotherium and Anaplotherium, which, according to Prof. Owen, had a type of structure intermediate between some of the types now existing, is another of these facts. And the comparatively recent appearance of Man, is a third fact of this kind, which possesses still greater significance.*<*I leave these sentences as they stood when written nearly forty years ago, thinking it better to name in a note the vast amount of confirmatory evidence which has accumulated in the interval, and which renders unassailable the conclusion drawn. In 1862 no one thought it possible that there could be proof of a transition between reptiles and birds; and yet since that time forms unquestionably transitional have been found. Though the indications of many other such kinships, by the discoveries of intercalary forms, have not yet in most cases been followed by proofs of continuous genealogy, yet it is otherwise in the case of the horse, the ancestry of which has been traced. Evidence of descent from a three-toed animal of the Miocene period is considered by Prof. Huxley as conclusive: sceptical and cautious though he is. In his Inaugural Address to the Geological Society in 1870, on "Paleontology and the Doctrine of Evolution." many further illustrations are given of kinships between ancient and modern types. Nowadays, indeed, there is universal agreement among naturalists (a few surviving disciples of Cuvier in France being excepted) that all organic forms have arisen by the superposing of modifications upon modifications: increase in heterogeneity being an average implication.>
Hence we may say that though our knowledge of past life upon the Earth is relatively small, yet what we have, and what we continually add to it, support the belief that there has been an evolution of the simple into the complex alike in individual forms and in the aggregate of forms.

§121. Advance from the homogeneous to the heterogeneous is clearly displayed in the progress of the latest and most heterogeneous creature -- Man. While the peopling of the Earth has been going on, the human organism has grown more heterogeneous among the civilized divisions of the species; and the species, as a whole, has been made more heterogeneous by the multiplication of races and the differentiation of them from one another. In proof of the first of these statements may be cited the fact that, in the relative development of the limbs, civilized men depart more widely from the general type of the placental mammalia, than do the lowest men. Though often possessing well-developed body and arms, the Papuan has very small legs: thus reminding us of the man-like apes, in which there is no great contrast in size between the hind and fore limbs. But in the European, the greater length and massiveness of the legs has become marked -- the fore and hind limbs are relatively more heterogeneous. The greater ratio which the cranial bones bear to the facial bones, illustrates the same truth. Among the Vertebrata in general, evolution is marked by an increasing heterogeneity in the vertebral column, and especially in the components of the skull: the higher forms being distinguished by the relatively larger size of the bones which cover the brain, and the relatively smaller size of those which form the jaws, etc. Now this trait, which is stronger in Man than in any other creature, is stronger in the European than in the savage. Moreover, from the greater extent and variety of faculty he exhibits, we may infer that the civilized man has also a more complex or heterogeneous nervous system than the uncivilized man; and, indeed, the fact is in part visible in the increased ratio which his cerebrum bears to the subjacent ganglia. If further elucidation be needed, every nursery furnishes it. In the infant European we see sundry resemblances to the lower human races; as in the flatness of the alae of the nose, the depression of its bridge, the divergence and forward opening of the nostrils, the form of the lips, the absence of a frontal sinus, the width between the eyes, the smallness of the legs. Now as the developmental process by which these traits are turned into those of the adult European, is a continuation of that change from the homogeneous to the heterogeneous displayed during the previous evolution of the embryo; it follows that the parallel developmental process by which the like traits of the barbarous races have been turned into those of the civilized races, has also been a continuation of the change from the homogeneous to the heterogeneous. The truth of the second statement is so obvious as scarcely to need illustration. Every work on Ethnology, by its divisions and subdivisions of races, bears testimony to it. Even were we to admit that Mankind originated from several separate stocks, it would still remain true that as, from each of these stocks, there have sprung many now widely different tribes, which are proved by philological evidence to have had a common origin, the race as a whole is more heterogeneous than it once was. Add to which that we have, in the Anglo-Americans, an example of a new variety arising within these few generations; and that, if we may trust to the descriptions of observers, we are likely soon to have another such in Australia.

§122. On passing from Humanity under its individual form to Humanity as socially embodied, we find the general law still more variously exemplified. The change from the homogeneous to the heterogeneous is displayed equally in the progress of civilization as a whole, and in the progress of every tribe or nation; and it is still going on with increasing rapidity.

Society in its first and lowest stage is a homogeneous assemblage of individuals having like powers and like functions: the only marked difference of function being that which accompanies difference of sex. Every man is warrior, hunter, fisherman, tool-maker, builder; every woman performs the same drudgeries; every family is self-sufficing, and, save for purposes of companionship, aggression, and defence, might as well live apart from the rest. Very early, however, in the course of social evolution, we find an incipient differentiation between the governing and the governed. Some kind of chieftainship soon arises after the advance from the state of separate wandering families to that of a nomadic tribe. The authority of the strongest and cunningest makes itself felt among savages, as in a herd of animals or a posse of schoolboys: especially in war. At first, however, it is indefinite, uncertain; is shared by others of scarcely inferior power; and is unaccompanied by any difference in occupation or style of living: the first ruler kills his own game, makes his own weapons, builds his own hut, and, economically considered, does not differ from others of his tribe. Along with conquests and the massing of tribes, the contrast between the governing and the governed grows more decided. Supreme power becomes hereditary in one family; the head, first military and then political, ceasing to provide for his own wants, is served by others; and he begins to assume the sole office of ruling. At the same time there has been arising a co-ordinate species of government -- that of Religion. Ancient records and traditions show that the earliest conquerors and kings came to be regarded as divine personages. The maxims and commands they uttered during their lives were held sacred after their deaths, and were enforced by their divinely-descended successors; who in their turns were promoted to the pantheon of the race, there to be worshipped and propitiated along with their predecessors. For a long time these connate forms of government -- civil and religious -- remain closely associated. For many generations the king continues to be the chief priest, and the priesthood to be members of the royal race. For many ages religious law continues to contain more or less of civil regulation, and civil law to possess more or less of religious sanction; and even among the most advanced nations these two controlling agencies are by no means completely differentiated from each other. Having a common root with these, and gradually diverging from them, we find yet another controlling agency -- that of Manners or ceremonial usages. Titles of honour were originally the names of the god-king; afterwards of God and the king; still later of persons of high rank; and finally came, some of them, to be used between man and man. Forms of complimentary address were at first expressions of propitiation from prisoners to their conqueror, or from subjects to their ruler, either human or divine -- expressions that were afterwards used subordinate authorities, and slowly descended into ordinary intercourse. Modes of salutation were once signs of subjection to a victor, afterwards obeisances made before the monarch and used in worship of him when dead. Presently others of the god-descended race were similarly saluted; and by degrees some of the salutations have become the due of all.*<* For detailed proof see essay on "Manners and Fashion" in Essays, etc., Vol. III.> Thus, no sooner does the originally homogeneous social mass differentiate into the governed and the governing parts, than this last exhibits an incipient differentiation into religious and secular-Church and State; while at the same time or still earlier there begins to take shape, that less definite species of government which rules our daily intercourse -- a species of government which, as we may see in heralds' colleges, in books of the peerage, in masters of ceremonies, is not without a certain embodiment of its own. Each of these kinds of government is itself subject to successive differentiations. In the course of ages, there arises, as among ourselves, a highly complex political organization of monarch, ministers, lords and commons, with their subordinate administrative departments, courts of justice, revenue offices, etc., supplemented in the provinces by municipal governments, county governments, parish or union governments -- all of them more or less elaborated. By its side there grows up a highly complex religious organization, with its various grades of officials from archbishops down to sextons, its colleges, convocations, ecclesiastical courts, etc.; to all which must be added the ever-multiplying independent sects, each with its general and local authorities. And simultaneously there is developed a complicated system of customs, manners, and temporary fashions, enforced by society at large, and serving to control those minor transactions between man and man which are not regulated by civil and religious law. Moreover, it is to be observed that this increasing heterogeneity in the governmental appliances of each nation, has been accompanied by an increasing heterogeneity in the governmental appliances of different nations. All peoples are more or less unlike in their political systems and legislation, in their creeds and religious institutions, in their customs and ceremonial usages.

Meanwhile there has been going on a differentiation of a more familiar kind; that, namely, by which the mass of the community has been segregated into distinct classes and orders of workers. While the governing part has undergone the complex development above indicated, the governed part has undergone a more complex development, which has resulted in that minute division of labour characterizing advanced nations. It is needless to trace out this progress from its first stages, up through the caste-divisions of the East and the incorporated guilds of Europe, to the elaborate producing and distributing organization existing among ourselves. Political economists have long since described the industrial progress which, through increasing division of labour, ends with a civilized community whose members severally perform different actions for one another; and they have further pointed out the changes through which the solitary producer of any one commodity, is transformed into a combination of producers who, united under a master, take separate parts in the manufacture of such commodity. But there are yet other and higher phases of this advance from the homogeneous to the heterogeneous in the industrial organization of society. Long after considerable progress has been made in the division of labour among the different classes of workers, there is relatively little division of labour among the widely separated parts of the community: the nation continues comparatively homogeneous in the respect that in each district the same occupations are pursued. But when roads and other means of transit become numerous and good, the different districts begin to assume different functions, and to become mutually dependent. The calico-manufacture locates itself in this county, the woollen-manufacture in that; silks are produced here, lace there; stockings in one place, shoes in another; pottery, hardware, cutlery, come to have their special towns; and ultimately every locality grows more or less distinguished from the rest by the leading occupation carried on in it. Nay, more, this subdivision of functions shows itself not only among the different parts of the same nation, but among different nations. That exchange of commodities which free-trade promises so greatly to increase, will ultimately have the effect of specializing, in a greater or less degree, the industry of each people. So that beginning with a primitive tribe, almost if not quite homogeneous in the functions of its members, the progress has been, and still is, towards an economic aggregation of the whole human race; growing ever more heterogeneous in respect of the separate functions assumed by separate nations, the separate functions assumed by the local sections of each nation, the separate functions assumed by the many kinds of producers in each place, and the separate functions assumed by the workers united in growing or making each commodity. And then, lastly, has to be named the vast organization of distributers, wholesale and retail, forming so conspicuous an element in our town-populations, which is becoming ever more specialized in its structure.

§123. Not only is the law thus exemplified in the evolution of the social organism, but it is exemplified in the evolution of all products of human thought and action, whether concrete or abstract, real or ideal. Let us take Language as our first illustration.

The lowest form of language is the exclamation, by which an entire idea is vaguely conveyed through a single sound; as among the lower animals. That human language ever consisted solely of exclamations, and so was strictly homogeneous in respect of its parts of speech, we have no evidence. But that language can be traced down to a form in which nouns and verbs are its only elements, is an established fact. In the gradual multiplication of parts of speech out of these primary ones -- in the differentiation of verbs into active and Passive, of nouns into abstract and concrete - in the rise of distinctions of mood, tense, person, or number and case -- in the formation of auxiliary verbs, of adjectives, adverbs, pronouns, prepositions, articles -- in the divergence of those orders, genera, species, and varieties of parts of speech by which civilized races express minute modifications of meaning; we see a change from the homogeneous to the heterogeneous. And it may be remarked that it is more especially because it has carried this subdivision of functions further than any other language, that the English language is structurally superior. Another process throughout which we may trace the development of language, is the differentiation of words of allied meanings. Philology early disclosed the truth that in all languages words may be grouped into families having each a common ancestry. An aboriginal name, applied indiscriminately to each member of an extensive and ill-defined class of things or actions, presently undergoes modifications by which the chief divisions of the class are expressed. These several names springing from the primitive root, themselves become the parents of other names still further modified. And by the aid of those systematic modes, which presently arise, of making derivatives and forming compounds expressing still smaller distinctions, there is finally developed a tribe of words so heterogeneous in sound and meaning, that to the initiated it seems incredible they should have had a common origin. Meanwhile, from other roots there are being evolved other such tribes, until there results a language of a hundred thousand different words, signifying as many different objects, qualities, acts. Yet another way in which language advances from the homogeneous to the heterogeneous, is by the multiplication of languages. Whether, as Max Müller and Bunsen think, all languages have grown from one stock, or whether, as some philologists say, they have grown from two or more stocks, it is clear that since large families of languages, as the Indo-European, are of one parentage, there have arisen multiplied kinds through a process of continuous divergence. The diffusion over the Earth's surface which has led to differentiation of the race, has simultaneously led to differentiation of its speech: a truth which we see further illustrated in each country by the dialects found in separate districts. Thus linguistic changes conform to the general law, alike in the evolution of languages, in the evolution of families of words, and in the evolution of parts of speech. If in our conception of language we include not its component words only but those combinations of them by which distinct ideas are conveyed -- namely sentences -- we have to recognize one more aspect of its progress from homogeneity to heterogeneity which has accompanied the progress in integration. Rude speech consists of simple propositions having subjects and predicates indefinitely linked; and anything like a complex meaning is conveyed by a succession of such propositions connected only by juxtaposition. Even in the speech of comparatively developed peoples, as the Hebrews, we find very little complexity. Compare a number of verses from the Bible with some paragraphs from a modern writer, and the increase in heterogeneity of structure is very conspicuous. And beyond the fact that many of our ordinary sentences are by the supplementary clauses, secondary propositions, and qualifying phrases they contain made relatively involved, there is the fact that there is great variety among the sentences in a page: now long, now short, now formed in one way, now in another, so that a double progress in heterogeneity in the style of composition is displayed.

On passing from spoken to written language, we come upon several classes of facts, having similar implications. Written language is connate with Painting and Sculpture; and at first all three are appendages of Architecture, and have a direct connexion with the early form of settled government -- the theocratic. Merely noting the fact that sundry wild races, as the Australians and the tribes of South Africa, are given to depicting personages and events on the walls of caves, which are probably regarded as sacred places, let us pass to the case of the Egyptians. Among them, as also among the Assyrians, we see mural paintings used to decorate the temple of the god and the palace of the king (which were, indeed, originally identical); and as such they were governmental appliances in the same sense that stage-pageants and religious feasts were. Further, they were governmental appliances in virtue of representing the worship of the god, the triumphs of the god-king, the submission of his subjects, and the punishment of the rebellious. And yet again they were governmental, as being the products of an art reverenced by the people as a sacred mystery. From the constant use of this pictorial representation, there grew up the but slightly-modified practice of picture-writing -- a practice which was found still extant among the Mexicans at the time they were discovered. By abbreviations analogous to those still going on in our own language, the most familiar of these pictured figures were successively simplified; and ultimately there grew up symbols, most of which had but distant resemblances to the things for which they stood. The inference that the hieroglyphics of the Egyptians thus arose, is confirmed by the fact that the picture-writing of the Mexicans was found to have given birth to a like family of ideographic forms; and among them, as among the Egyptians, these had been partially differentiated into the kuriological or imitative, and the tropical or symbolic: which were, however, used together in the same record. In Egypt, written language underwent a further differentiation, resulting in the hieratic and the epistolographic or enchorial: both derived from the original hieroglyphic. At the same time for proper names, which could not be otherwise expressed, phonetic symbols were employed; and though the Egyptians never achieved complete alphabetic writing, yet it can scarcely be doubted that among other peoples phonetic symbols, occasionally used in aid of ideographic ones, were the germs out of which alphabetic writing arose. Once having become separate from hieroglyphics, alphabetic writing itself underwent numerous differentiations -- multiplied alphabets were produced: between most of which, however, connexions can still be traced. And in each civilized nation there have now grown up, for the representation of one set of sounds, several sets of written signs, used for distinct purposes. Finally, through a yet more important differentiation came printing; which, uniform in kind as it was at first, has since become multiform.

§124. While written language was passing through its earlier stages of development, the mural decoration which formed its root was being differentiated into Painting and Sculpture. The gods, kings, men, and animals represented, were originally marked by indented outlines and coloured. In most cases these outlines were of such depth, and the object they circumscribed so far rounded, as to form a species of work intermediate between intaglio and bas-relief. In other cases we see an advance upon this: the spaces between the figures being chiselled out, and the figures themselves appropriately tinted, a painted bas-relief was produced. The restored Assyrian architecture at Sydenham exhibits this style of art carried to greater perfection: the persons and things represented, though still barbarously coloured, are carved with more truth and in greater detail; and in the winged lions and bulls used for the angles of gateways, we see advance towards a completely sculptured figure; which, nevertheless, is still coloured and still forms part of the building. But though in Assyria the production of a statue proper seems to have been little, if at all, attempted, we may trace in Egyptian art the gradual separation of the sculptured figure from the wall. While a walk through the collection in the British Museum will afford an opportunity of observing transitions, it will bring into view much evidence that the independent statues were derived from bas-reliefs: newly all of them not only display that lateral attachment of the arms with the body which is a characteristic of bas-relief, but have the back of the statue united from head to foot with a block which stands in place of the original wall. Greece repeated the leading stages of this progress. As in Egypt and Assyria, these twin arts were at first united with each other and with their parent, Architecture; and were aids of Religion and Government. On the friezes of Greek temples, we see coloured bas-reliefs representing sacrifices, battles, processions, games -- all in some sort religious. On the pediments we see painted sculptures partially united with the tympanum, and having for subjects the triumphs of gods or heroes. Even when we come to statues that are definitely separated from the buildings to which they pertain, we still find them coloured; and only in the later periods of Greek civilization, does the differentiation of painting from sculpture appear to have become complete. In Christian art there occurred a parallel re-genesis. All early paintings and sculptures throughout Europe were religious in subject -- represented Christs, crucifixions, virgins, holy families, apostles, saints. They formed integral parts of church architecture, and were among the means of exciting worship: as in Roman Catholic countries they still are. Moreover, the early sculptures of Christ on the cross, of virgins, of saints, were coloured; and it needs but to call to mind the painted madonnas and crucifixes still abundant in continental churches, to perceive the significant fact that painting and sculpture continue in closest connexion with each other, where they continue in closest connexion with their parent. Even when Christian sculpture become separate from painting, it was still at first religious and governmental in its subjects -- was used for tombs in churches and statues of saints and kings; while, at the same time, painting, where not purely ecclesiastical, was applied to the decoration of palaces, and after representing royal personages, was almost wholly devoted to sacred legends. Only in modern times have painting and sculpture become entirely secular arts. Only within these few centuries has painting been divided into historical, landscape, marine, architectural, animal, still-life, etc., and sculpture grown heterogeneous in respect of the variety of real and ideal subjects with which it occupies itself.

Strange as it seems then, all forms of written language, of painting, of sculpture, have a common root in those rude drawings on skins and cavern-walls by which savages commemorated notable deeds of their chiefs, and which, during social progress, developed into the politico-religious decorations of ancient temples and palaces. Little resemblance as they now have, the bust that stands on the console, the landscape that hangs against the wall, and the copy of The Times lying upon the table, are remotely akin. The brazen face of the knocker which the postman has just lifted, is related not only to the woodcuts of the Illustrated London News which he is delivering, but to the characters of the billet-doux which accompanies it. Between the painted window the prayer-book on which its light falls, and the adjacent monument, there is consanguinity. The effigies on our coins, the signs over shops, the figures that fill every ledger, the coat-of-arms outside the carriage-panel, and the placards inside the omnibus, are, in common with dolls, blue-books, and paper-hangings, lineally descended from the sculpture-paintings and picture-writings in which the Egyptians represented and recorded the triumphs and worship of their god-kings. Perhaps no example can be given which more vividly illustrates the multiplicity and heterogeneity of the products that in course of time may arise by successive differentiations from a common stock.

The transformation of the homogeneous into the heterogeneous thus displayed in the separation of Painting and Sculpture from Architecture and from each other, and in the greater variety of subjects they embody, is further displayed in the structure of each work. A modern picture or statue is of far more complex nature than an ancient one. An Egyptian sculpture-fresco represents all its figures as on one plane -- that is, at the same distance from the eye; and so is less heterogeneous than a painting that represents them as at various distances. It exhibits all objects as similarly lighted; and so is less heterogeneous than a painting which exhibits different objects, and different parts of each object, as in different degrees of light. It uses scarcely any but the primary colours, and these in their full intensities; and so is less heterogeneous than a painting which, introducing the primary colours but sparingly, employs an endless variety of intermediate tints, each of heterogeneous composition, and differing from the rest not only in quality but in strength. Moreover, these earliest works manifest great uniformity of conception. In ancient societies the modes of representation were so fixed that it was sacrilege to introduce a novelty. In Egyptian and Assyrian bas-reliefs, deities, kings, priests, attendants, winged-figures and animals, are in all cases depicted in like positions, special to each class, holding like implements, doing like things, and with like expression or non-expression of face. If a palm-grove is introduced, all the trees are of the same height, have the same number of leaves, and are equidistant. When water is imitated, each wave is a counterpart of the rest; and the fish, almost always of one kind, are evenly distributed. The beards of the Assyrian kings, gods, and winged-figures, are everywhere similar; as are the manes of the lions, and equally so those of the horses. Hair is represented throughout by one form of curl. The king's beard is built up of compound tiers of uniform curls, alternating with twisted tiers placed transversely and arranged with perfect regularity; and the terminal tufts of the bulls' tails are represented in exactly the same manner. Without tracing out analogous traits in early Christian art, in which, though less striking, they are still visible, the advance in heterogenity will be sufficiently manifest on remembering that in the pictures of our own day the composition is endlessly varied; the attitudes, faces, expressions, unlike; the subordinate objects different in size, form, position, texture. Or, if we compare an Egyptian statue, seated upright on a block, with hands on knees, fingers outspread and parallel, eyes looking straight forward, and the two sides perfectly symmetrical, with a statue of the advanced Greek or the modern school, which is asymmetrical in respect of the position of the head, the body, the limbs, the arrangement of the hair, dress, appendages, and in its relations to neighbouring objects, we see the change from the homogeneous to the heterogeneous clearly manifested.

§125. In the co-ordinate origin and gradual differentiation of Poetry, Music, and Dancing, we have another series of illustrations. Rhythm in speech, rhythm in sound, and rhythm in motion, were in the beginning, parts of the same thing. Among existing barbarous tribes we find them still united. The dances of savages are accompanied by some kind of monotonous chant, the clapping of hands, the striking of rude instruments: there are measured movements, measured words, and measured tones; and the whole ceremony, usually having reference to war or sacrifice, is of governmental character. The early records of the historic races similarly show these three forms of metrical action united in religious festivals. In the Hebrew writings we read that the triumphal ode composed by Moses on the defeat of the Egyptians, was sung to an accompaniment of dancing and timbrels. The Israelites danced and sung "at the inauguration of the golden calf. And as it is generally agreed that this representation of the Deity was borrowed from the mysteries of Apis, it is probable that the dancing Was copied from that of the Egyptians on those occasions." There was an annual dance in Shiloh on the sacred festival; and David danced before the ark. Again, in Greece the like relation existed: the original type being there, as probably in other cases, a simultaneous chanting and mimetic representation of the achievements of the god. The Spartan dances were accompanied by hymns; and in general the Greeks had "no festivals or religious assemblies but what were accompanied with songs and dances" -- both of them being forms of worship used before altars. Among the Romans, too, there were sacred dances: the Salian and Lupercalian being named as of that kind. Even in the early Christian church, dances in the choir at festivals, occasionally led by bishops, were among the forms of worship, and in some places continued down to the 18th century. The incipient separation of these once united arts from each other and from religion, was early visible in Greece. Probably diverging from dances partly religious, partly warlike, as the Corybantian, came the war-dances proper, of which there were various kinds; and from these resulted secular dances. Meanwhile Music and Poetry, though still joined, came to have an existence separate from dancing. The primitive Greek poems, religious in subject, were not recited but chanted; and though at first the chant of the poet was accompanied by the dance of the chorus, it ultimately grew into independence. Later still, when the poem had been differentiated into epic and lyric -- when it became the custom to sing the lyric and recite the epic-poetry proper was born. As, during the same period, musical instruments were being multiplied, we may presume that music came to have an existence apart from words. And both of them were beginning to assume other forms than the religious. Facts having like implications might be cited from the histories of later times and peoples: as the practices of our Anglo-Saxon "gleemen" and Celtic bards, who sang to the harp heroic narratives versified by themselves to music of their own composition: thus uniting the now separate offices of poet, composer, vocalist, and instrumentalist. The common origin and gradual differentiation of Dancing, Poetry, and Music is thus sufficiently manifest.

Besides being displayed in the separation of these arts from one another and from religion, growing heterogeneity is also displayed in the multiplied differentiations which each of them afterwards undergoes. Just referring to the numberless kinds of dancing that have, in course of time, come into use, and to the progress of poetry, as seen in the development of the various forms of metre, of rhyme, and of general organization, let us confine our attention to music as a type of the group. As argued by Dr. Burney, and as implied by the customs of extant savages, the first musical instruments were percussive-sticks, calabashes, tom-toms -- and were used simply to mark the time of the dance. So, too, the vocal music of various semi-civilized races consists of simple phrases endlessly reiterated. In this constant repetition of the same sounds we see music in its most homogeneous form. The Egyptians had a lyre with three strings. The early lyre of the Greeks had four, constituting their tetrachord. In course of some centuries lyres of seven and eight strings came to be employed. And, by the expiration of a thousand years, they had advanced to their "great system" of the double octave. Through all which changes of course arose a greater heterogeneity of melody or rather recitative. Simultaneously came into use the different modes -- Dorian, Ionian, Phrygian, AEolian, and Lydian -- answering to our keys; and of these there were ultimately fifteen. As yet, however, there was but little heterogeneity in the time of their music. Instruments being used merely to accompany the voice, the vocal music being completely subordinated to words, -- the singer being also the poet, chanting his own compositions and making the lengths of his notes agree with the feet of his verses -- there unavoidably arose a tiresome uniformity of measure which, as Dr. Burney says, "no resources of melody could disguise." Lacking the complex rhythm obtained by our equal bars and unequal notes, the only rhythm was that produced by the quantity of the syllables, and was of necessity monotonous. And further, the chant thus resulting being like recitative, was much less differentiated from ordinary speech than is our modern song. Nevertheless, considering the extended range of notes in use, the variety of modes, the occasional variations of time consequent on changes of metre, and the multiplication of instruments, we see that music had, towards the close of Greek civilization, attained to considerable heterogeneity: not indeed as compared with our music, but as compared with that which preceded it. As yet, however, there existed nothing but serial combinations of notes (for so we must call them since they were not melodies in our sense): harmony was unknown. It was not until Christian church-music had reached some development, that music in parts was evolved; and then it came into existence through an unobtrusive differentiation. The practice which led to it was the employment of two choirs singing alternately the same air. Afterwards it became the habit (possibly first suggested by a mistake) for the second choir to commence before the first had ceased: thus producing a fugue. With the simple airs then in use, a partially harmonious fugue might not improbably result; and a very partially harmonious fugue satisfied the ears of that age, as we know from still preserved examples. The idea having once been given, the composing of airs productive of fugal harmony would naturally grow up; as in some way it did grow up out of this alternate choir-singing. And from the fugue to concerted music of two, three, four, and more parts, the transition was easy. Without pointing out in detail the increasing complexity that resulted from introducing notes of various lengths, from the multiplication of keys, from the use of accidentals, from varieties of time, from modulations and so forth, it needs but to contrast music as it is with music as it was, to see how immense is the increase of heterogeneity. We see this also if, looking at music in its ensemble, we enumerate its many different genera and species -- if we consider the divisions into vocal, instrumental, and mixed; and their subdivisions into music for different voices and different instruments -- if we observe the many forms of sacred music, from the simple hymn, the chant, the canon, motet, anthem, etc., up to the oratorio; and the still more numerous forms of secular music, from the ballad up to the serenata, from the instrumental solo up to the symphony. Again, the same truth is seen on comparing any one sample of aboriginal music with a sample of modern music -- even an ordinary song for the piano; which we find to be relatively very heterogeneous, not only in respect of varieties in the intervals and in the lengths of the notes, the number of different notes sounding at the same instant in company with the voice, and the variations of strength with which they are sounded and sung, but in respect of the changes of key, the changes of time, the changes of timbre of the voice, and the many other modifications of expression. While between the old monotonous dance-chant and a grand opera of our own day, the contrast in heterogeneity is so extreme that it seems scarcely credible that the one is the ancestor of the other.

§126. Many further illustrations of the general law throughout social products might be detailed. Going back to the time when the deeds of the god-king, chanted and mimetically represented in dances before his altar, were further narrated in picture-writings on the walls of temples and palaces, and so constituted a rude history, we might trace the development of Literature through phases in which, as in the Hebrew Scriptures, it presents in one work, theology, cosmogony, history, biography, civil laws, ethics, poetry; through other phases in which, as in the Iliad, the religious, martial, historical, the epic, dramatic, and lyric elements are similarly commingled; down to its present heterogeneous development, in which its divisions and subdivisions are so numerous and varied as to defy complete classification. Or we might track the unfolding of Science; beginning with the era in which it was not yet differentiated from Art, and was, in union with Art, the handmaid of Religion; passing through the era in which the sciences were so few and rudimentary, as to be simultaneously cultivated by the same philosophers; and ending with the era in which the genera and species are so multitudinous that few can enumerate them, and no one can adequately grasp even one genus. Or we might do the like with Architecture, with the Drama, with Dress. But doubtless the reader is already weary of illustrations, and my promise has been amply fulfilled. The advance from the simple to the complex through successive modifications upon modifications, is seen alike in the earliest changes of the Heavens to which we can reason our way back, and in the earliest changes we can inductively establish; it is seen in the geologic and climatic evolution of the Earth, of every individual organism on its surface and in the aggregate of organisms; it is seen in the evolution of Humanity, whether contemplated in the civilized man, or in the assemblage of races; it is seen in the evolution of Society, in respect alike of its political, its religious, and its economical organization; and it is seen in the evolution of those countless concrete and abstract products of human activity, which constitute the environment of our daily life. From the remotest past which Science can fathom, up to the novelties of yesterday, an essential trait of Evolution has been the transformation of the homogeneous into the heterogeneous.

§127. So that the general formula arrived at in the last chapter needs supplementing. It is true that Evolution, under its primary aspect, is a change from a less coherent state to a more coherent state, consequent on the dissipation of motion and integration of matter; but this is far from being the whole truth. Along with a passage from the coherent to the incoherent, there goes on a passage from the uniform to the multiform. Such, at least, is the fact wherever Evolution is compound; which it is in the immense majority of cases. While there is a progressing concentration of the aggregate, caused either by the closer approach of the matter within its limits, or by the drawing in of further matter, or by both; and while the more or less distinct parts into which the aggregate divides and subdivides are also severally concentrating; these parts are simultaneously becoming unlike -- unlike in size, or in form, or in texture, or in composition, or in several or all of these. The same process is exhibited by the whole and by its members. The entire mass is integrating, and at the same time differentiating from other masses; while each member of it is also integrating and at the same time differentiating from other members.

Our conception, then, must unite these characters. As we now understand it, Evolution is definable as a change from an incoherent homogeneity to a coherent heterogeneity, accompanying the dissipation of motion and integration of matter.