R82¥ZVl? Walsh Philosophy Collection PRESENTED to the LIBRARIES of the UNIVERSITY 0/TORONTO OUTLINES OF COSMIC PHILOSOPHY IN FOUR VOLUMES VOLUME II OUTLINES OF COSMIC PHILOSOPHY BASED ON THE DOCTRINE OF EVOLUTION, WITH CRITICISMS ON THE POSITIVE PHILOSOPHY BY JOHN FISKE WITH AN INTRODUCTION BY JOSIAH ROYCE ISunivers, pour qui sauraii Pembrasser with almost malicious rapidity, falsified his words. In less than four years, Bessel had measured the paral- lax of the star 6 1 Cygni, — the first of a bril- liant series of discoveries which by this time have made the starry heavens comparatively familiar ground to us. What would Comte's scorn have been, had it been suggested to him that within a third of a century we should pos- sess many of the data for a science of stellar chemistry ; that we should be able to say, for instance, that Aldebaran contains sodium, mag- nesium, calcium, iron, bismuth, and antimony, or that all the stars hitherto observed with the spectroscope contain hydrogen, save (3 Pegasi and a Orionis, which apparently do not ! Or what would he have said, had it been told him that, by the aid of the same instrument which characteristics of certain observed or inferred redistributions of the matter and motion already existing. The latter attempt is as clearly within the limits of a scientific philosophy as the former is clearly beyond them. 93 COSMIC PHILOSOPHY now enables us to make with perfect confidence these audacious assertions, we should be able to determine the proper motions of stars which present no parallax ! No example could more forcibly illustrate the rashness of prophetically- setting limits to the possible future advance of science. Here are truths which, within the mem- ory of young men, seemed wholly out of the reach of observation, but which are already fa- miliar, and will soon become an old story. I believe it was Comte's neglect of psycho- logical analysis which caused him to be thus over-conservative in accepting new discoveries, and over-confident in setting limits to scien- tific achievement. He did not clearly distin- guish between the rashness of metaphysics and the well-founded boldness of science. He was deeply impressed with the futility of wasting time and mental energy in constructing unveri- fiable hypotheses ; but he did not sufficiently distinguish between hypotheses which are tem- porarily unverifiable from present lack of the means of observation, and those which are per- manently unverifiable from the very nature of the knowing process. There is no ground for supposing that Comte ever thoroughly under- stood why we cannot know the Absolute and the Infinite. He knew, as a matter of historical fact, that all attempts to obtain such knowledge had miserably failed, or ended in nothing better 94 PHILOSOPHY AS AN ORGANON than vain verbal wranglings ; but his ignorance of psychology was so great that he probably never knew, or cared to know, why it must necessarily be so. Had he ever once arrived at the knowledge that the process of knowing in- volves the cognition of likeness, difference, and relation, and that the Absolute, as presenting none of these elements, is trebly unknowable, he would never have confounded purely meta- physical hypotheses with those which are only premature but are nevertheless scientific. He would have seen, for instance, that our inability to say positively whether there are or are not liv- ing beings on Saturn results merely from our lack of sufficient data for a complete induction ; whereas our inability to frame a tenable hypo- thesis concerning matter -per se results from the eternal fact that we can know nothing save under the conditions prescribed by our mental structure. Could we contrive a telescope pow- erful enough to detect life, or the products of art, upon a distant planet, there is nothing in the constitution of our minds to prevent our appropriating such knowledge ; but no patience of observation or cunning of experiment can ever enable us to know the merest pebble as it exists out of relation to our consciousness. Simple and obvious as this distinction appears, there is much reason to believe that Comte never understood it. He inveighs against in- 95 COSMIC PHILOSOPHY quiries into the proximate origin of organic life in exactly the same terms in which he condemns inquiries into the ultimate origin of the uni- verse. He could not have done this had he perceived that the latter question is forever in- soluble because it involves absolute beginning ; whereas the former is merely a question of a particular combination of molecules, which we cannot solve at present only because we have not yet obtained the requisite knowledge of the interactions of molecular forces, and of the past physical condition of the earth's surface. In short, he would have seen that, while the Jiu- man mind is utterly impotent in the presence of noumena, it is well-nigh omnipotent in the presence of phenomena. In science we may be said to advance by geometrical progression. Here, in the forty years which have elapsed since Comte wrote on physical science, it is hardly extravagant to say that the progress has been as great as during the seventeen hundred years between Hipparchos and Galileo. If then, in the three or four thousand years which have elapsed since Europe began to emerge from utter barbarism, we have reached a point at which we can begin to describe the chemical constitution of a heavenly body seventy thou- sand million miles distant, what may not science be destined to achieve in the next four thousand or forty thousand years ? We may rest assured 96 PHILOSOPHY AS AN ORGANON that the tale, if we could only read it, would far excel in strangeness anything in the " Ara- bian Nights " or in the mystic pages of the Bollandists. But Comte did not understand all this. He, the great overthrower and superseder of metaphysics, did not really apprehend the distinction between metaphysics and science. Hence every hypothesis which went a little way beyond the limited science of his day he wrongly stigmatized as " metaphysical." Hence he heaped contumely upon the cell-doctrine, only three years before Schwann and Schleiden finally established it. And hence, when he had occasion to observe that certain facts were not yet known, he generally added, " and probably they never will be," — though his prophecy was not seldom confuted, while yet warm from the press. Toward the close of his life, after he had be- come sacerdotally inclined, this tendency as- sumed a moral aspect. These remote and au- dacious inquiries into the movements of stars, and the development of cellular tissue, and the origin of species should not only be pronounced fruitless, but should be frowned upon and dis- countenanced by public opinion, as a pernicious waste of time and energy, which might better be devoted to nearer and more practical objects. It is a curious illustration of the effects of dis- vol. ii 97 COSMIC PHILOSOPHY cipleship upon the mind, that several of Comte's disciples — Dr. Bridges among others less dis- tinguished — maintain this same opinion, for no- earthly reason, I imagine, save that Comte held it. It is certainly a strange opinion for a philo- sopher to hold. It bears an unlovely resem- blance to the prejudice of the Philistines, that all speculation is foolish and empty which does not speedily end in bread-and-butter know- ledge. Who can decide what is useful and what is useless ? We are told first that we shall never know the distance to a star, and secondly that even if we could know it, the knowledge would be useless, since human interests are at the utter- most bounded by the solar system. Three years suffice to disprove the first part of the predic- tion. In a little while the second part may also be disproved. We are told by Comte that it makes no difference to us whether organic spe- cies are fixed or variable ; and yet, as the Dar- winian controversy has shown, the decision of this question must affect from beginning to end our general conception of physiology, of psy- chology, and of history, as well as our estimate of theology. If it were not universally felt to be of practical consequence, it would be argued calmly, and not with the weapons of ridicule and the odium theologicum. But this position — the least defensible one which Comte ever oc- cupied — may best be refuted by his own words, 98 PHILOSOPHY AS AN ORGANON written in a healthier frame of mind. " The most important practical results continually flow from theories formed purely with scientific in- tent, and which have sometimes been pursued for ages without any practical result. A remark- able example is furnished by the beautiful re- searches of the Greek geometers upon conic sections, which, after a long series of genera- tions, have renovated the science of astronomy, and thus brought the art of navigation to a pitch of perfection which it could never have reached but for the purely theoretic inquiries of Archimedes and Apollonios. As Condorcet well observes, the sailor, whom an exact calcu- lation of longitude preserves from shipwreck, owes his life to a theory conceived two thou- sand years ago by men of genius who were thinking of nothing but lines and angles." This is the true view ; and we need not fear that the scientific world will ever adopt any other. That inborn curiosity which, according to the Hebrew legend, has already made us like gods, know- ing good and evil, will continue to inspire us until the last secret of Nature is laid bare ; and doubtless, in the untiring search, we shall un- cover many priceless jewels, in places where we least expected to find them. The foregoing examples will suffice to illus- trate the vagueness with which Comte conceived the limits of scientific and of philosophic in- 99 COSMIC PHILOSOPHY quiry. I have here cited them, not so much for the sake of exhibiting Comte's mental idiosyn- crasies, as for the sake of emphasizing the radi- cal difference between his conception of the scope of philosophy and the conception upon which the Cosmic Philosophy is founded. In giving to Comte the credit which he deserves, for having heralded a new era of speculation in which philosophy should be built up entirely out of scientific materials, we must not forget that his conception of the kind of philosophy thus to be built up was utterly and hopelessly erroneous. Though he insisted upon the all- important truth that philosophy is simply a higher organization of scientific doctrines and methods, he fell into the error of regarding philosophy merely as a logical Organon of the sciences, and he never framed the conception of philosophy as a Universal Science in which the widest truths obtainable by the several sciences are contemplated together as corollaries of a single ultimate truth. Not only did he never frame such a conception, but there can be no doubt that, had it ever been presented to him in all its completeness, he would have heaped opprobrium upon it as a metaphysical conception utterly foreign to the spirit of Posi- tive Philosophy. We have just seen him reso- lutely setting his face against those very scien- tific speculations to which this conception of ioo PHILOSOPHY AS AN ORGANON the scope of philosophy owes its origin ; and we need find no difficulty in believing Dr. Bridges when he says that the Doctrine of Evo- lution would have appeared to his master quite as chimerical as the theories by which Thales and other Greek cosmogonists " sought to de- duce all things from the principle of Water or of Fire." Thus in a way that one would hardly have anticipated, we have disclosed a fundamental and pervading difference between the Positive and the Cosmic conceptions of philosophy. The apparently subordinate inquiry into Comte's reasons for excluding Logic from his scheme of sciences, has elicited an answer which gravely affects our estimate of his whole system of thought. That his conception of Philosophy as an Organon was a noble conception, there is no doubt ; but that it was radically different from our conception of Philosophy as a Synthesis, is equally undeniable. But the full depth and significance of this distinction will only be ap- preciated when, in the following chapter, we shall have pointed out the end or purpose for which this scientific Organon was devised. IOI CHAPTER X COSMISM AND POSITIVISM TOWARD the close of the chapter on " Phenomenon and Noumenon," I ob- served that it has become customary to identify with Positivism every philosophy which rejects all ontological speculation, which seeks its basis in the doctrines and methods of sci- ence, and which is accordingly arranged in op- position to the current mythologies. The con- fusion is one which, after having once been ori- ginated, it is easy to maintain but exceedingly difficult to do away with ; since on the one hand, it is manifestly convenient for the theologian to fasten upon every new and obnoxious set of doctrines the odium already attaching to quasi- atheistic Positivism ; while on the other hand, the disciples of Comte are not unnaturally eager to claim for themselves every kind of modern thinking that can by any colourable pretext be annexed to their own province. The theologi- cal magazine-writer, who perhaps does not know what is meant by the Relativity of Knowledge but feels that there is something to be dreaded in Mr. Mansel's negations, finds an excellent I02 COSMISM AND POSITIVISM substitute for intelligent criticism in the insinu- ation that this doctrine of relativity is a device of the Positivists, who refuse to admit the ex- istence of God, and worship Humanity " sym- bolized as a woman of thirty, with a child in her arms." In similar wise the ardent disciple of Comte — who, so far as my experience goes, is not unlikely to be quite as narrow-minded as any theologian — is wont to claim all contem- porary scientific thinkers as the intellectual off- spring of his master, until their openly expressed dissent has reduced him to the alternative of stigmatizing them as " metaphysical ; " very much as the Pope lays claim to the possession of all duly baptized Christians,1 save those whom it has become necessary to excommunicate and give over to the Devil. But aside from these circumstances, which partly explain the popular tendency to classify all scientific thinkers as Positivists, it is not to be denied that there are really plausible reasons why the Positive Philosophy should currently be regarded as representative of that whole genus of contemporary thinking which repudiates the subjective method, and, as Mr. Spencer says, " prefers proved facts to superstitions." As I have already shown, it was Comte who first inaugurated a scheme of philosophy explicitly 1 See the amusing letter of Pius IX. to the Emperor of Ger- many, dated August 7, 1873. 103 COSMIC PHILOSOPHY based upon the utter rejection of anthropo- morphism and the adoption of none but sci- entific doctrines and methods. I have already pointed out how great are our obligations to him for this important work, and I need not repeat the acknowledgment. For this reason it is obvious that whenever the theological thinker encounters a system which as far as possible rejects anthropomorphic interpretations, and whenever the metaphysician encounters a sys- tem which denies the validity of his subjective method, both the one and the other will quite naturally regard this system as some phase of Positivism. For the same reason, when we re- member how strong is the tendency to " read between the lines " of any system of thought and thus to interpret it in accordance with our preconceptions, we shall see how easy it is for those who first derived from Comte their no- tions of scientific method and of the limits of philosophic inquiry, to " read into " his system all the later results of their intellectual experi- ence, and thus to persist in regarding the whole as Positive Philosophy. Of this tendency it seems to me that we have an illustrious example in Mr. Lewes, the learned historian of philoso- phy and acute critic of Kant, who in the latest edition of his " History " still maintains that the agreement between Comte and Spencer is an agreement in fundamentals, while the differ- 104 COSMISM AND POSITIVISM ences between them are non-essential differences. That I am not incapable of understanding and sympathizing with this tendency, may be in- ferred from the fact that during eleven years I espoused the same plausible error, and called myself a Positivist (though never a follower of Comte) in the same breath in which I defended doctrines' that are utterly incompatible with Pos- itivism in any legitimate sense of the word. So long as we allow our associations with the words to colour and distort our scrutiny of the things, — a besetting sin of human philosophizing from which none of us can hope to have entirely freed himself, — so long it is possible for us to construct an apparently powerful argument in behalf of the fundamental agreement between Spencer and Comte. It may be said, for exam- ple, that both philosophers agree in asserting: I. That all knowledge is relative; II. That all unverifiable hypotheses are inad- missible ; III. That the evolution of philosophy, what- ever else it may be, has been a process of deanthropomorphization ; IV. That philosophy is a coherent organization of scientific doctrines and methods ; V. That the critical attitude of philosophy is not destructive but constructive, not iconoclastic but conservative, not nega- tive but positive. 105 COSMIC PHILOSOPHY Still confining our attention to the form of these propositions, and neglecting for the mo- ment the very different meanings with which they would be enunciated respectively by the Cosmist and by the Positivist, it is open to us to maintain that, in asserting these propositions, Mr. Spencer agrees with Comte in asserting the five cardinal theorems of Positive Philosophy. Looking at the matter in this light, we might complain that Mr. Spencer, in his " Reasons for Dissenting, etc.," accentuates the less funda- mental points in which he differs from Comte, and passes without emphasis the more funda- mental points in which he agrees with Comte. We might urge that while the " Law of the Three Stages " is undoubtedly incorrect, never- theless the essential point is that men's concep- tions of Cause have been becoming ever less and less Anthropomorphic. And similarly, when Mr. Spencer insists that Comte has not classified the sciences correctly, we might reply that, if we were to question M. Littre (who still holds to the chief positions of the Comtean classification), he would perforce admit that the fundamental point — the ground-question, as Germans say — is not whether physics comes after astronomy, or whether biology is an abstract science, but whether or not the sciences can be made to fur- nish all the materials for a complete and unified conception of the world. io6 COSMISM AND POSITIVISM In this statement of the case, which once seemed to me satisfactory, we have probably the strongest argument that can be devised in favour of the identification of Mr. Spencer's philosophy with Positivism. Yet, — as above hinted, and as will be self-evident to every one who has comprehended the foregoing chapters, — its apparent strength rests entirely upon the verbal ambiguity of the five cardinal proposi- tions, which are stated in such a way as to con- ceal the real points at issue between the two philosophies. With regard to the first two pro- positions, I have already shown that they are in nowise so peculiar to Comte that allegiance to them should make us his disciples or coadju- tors. In accepting the Doctrine of Relativity, as well as in receiving from modern science the in- heritance of the Objective Method, we are the " heirs of all the ages," and are in nowise espe- cially beholden to Comte. As regards the fifth proposition, concerning the critical attitude of philosophy, the discussion of it does not belong to our Prolegomena but to our Corollaries, since before we can comprehend it we must make sure that we understand what is implied by the Doc- trine of Evolution. In the concluding chapter of this work it will appear that our dissent from Positivism is practically no less emphatic in re- spect to the critical attitude of philosophy than in other respects. For the present we can will- 107 COSMIC PHILOSOPHY ingly dispense with this proof, as our point will be quite sufficiently established .by an examina- tion of the third and fourth propositions above alleged as cardinal alike to Positivism and to Cosmism. And first, as regards the fourth proposition, the preceding chapter showed that Comte's con- ception of the scope and functions of philosophy was by no means the same as that which lies at the bottom of the present work. We have seen that he treated philosophy as merely an Orga- non of scientific methods, and totally ignored the conception of philosophy as a Synthesis of truths concerning the Cosmos. Now in order to comprehend the full purport of this, we must ask what was Comte's aim in constructing a sys- tem of philosophy ? To what end was this elaborate Organon devised? It was not devised for the purpose of aiding the systematic explo- ration of nature in all directions, for we have seen that Comte began by discouraging and ended by anathematizing a large class of most important inquiries, chiefly on the ground of their " vainness " or " inutility." To under- stand the purpose of all this admirable treat- ment of philosophy as an Organon, we must take into account the statement of Dr. Bridges that Comte's philosophic aims were not differ- ent in his later epoch from what they had been in the earlier part of his career. From the very 1 08 COSMISM AND POSITIVISM outset Comte intended to crown his work of reorganizing philosophy by constructing a polity which should be competent to reorganize so- ciety. The belief that society can be regener- ated by philosophy is a belief which underlies all his speculations from first to last. His aims were as practical as those of Saint-Simon and Fourier, the difference being chiefly that these unscientific dreamers built their Utopias upon abstract theories of human nature, while Comte sought to found his polity upon the scientific study of the actual tendencies of humanity as determined by its past history. In a future chapter I shall have occasion to show that this whole attempt of Comte's was based upon a profound misconception of the true state of the case. For the present we need only observe that with Comte the construction of a Philosophy meant ultimately the construction of a Sociology, to which all his elaborate sys- tematization of scientific methods was intended to be ancillary. Why must we study observa- tion in astronomy, experiment in physics and chemistry, comparison in biology ? In order, says Comte, to acquire the needful mental train- ing for sound theorizing in sociology. To him the various physical sciences were not sources from which grand generalizations were to be derived, embracing the remotest and most sub- tle phenomena of the 'Universe ; they were 109 COSMIC PHILOSOPHY whetstones upon which to grind the logical im- plements to be used in constructing a theory of Humanity. All other theorizing was to be con- demned, save in so far as it could be shown to be in some way subservient to this purpose. Thus Comte's conception of philosophy was throughout anthropocentric, and he utterly ig- nored the cosmic point of view. There can be little doubt that he who, in 1830, rejected the development-theory, which a more prescient thinker, like Goethe, was enthusiastically pro-' claiming, would have scorned as chimerical and useless Mr. Spencer's theory of evolution. We may now begin to see why Comte wished to separate Man from the rest of the organic crea- tion, and why he was so eager to condemn side- real astronomy, the study of which tends in one sense to dwarf our conceptions of Human- ity. Comte was indeed too much of an astro- nomer to retreat upon the Ptolemaic theory, but in his later works he shows symptoms of a feeling like that which actuated Hegel, when he openly regretted the overthrow of the an- cient astronomy, because it was more dignified for man to occupy the centre of the universe ! It is true that in his first great work Comte points out the absurdity of the theological view of man's supremacy in the universe, and rightly ascribes to the Copernican revolution a consid- erable share in the overthrowing of this view, no COSMISM AND POSITIVISM and of the doctrine of final causes, with which it is linked. In spite of all this, however, and in spite of his admirable scientific preparation, Comte's conception of philosophy as the sum- mary of a hierarchy of sciences, presided over by sociology, led him irresistibly toward the an- thropocentric point of view ; and so, when it became necessary for him to crown his work by indicating its relations to religion, he arrived, logically enough, at a Religion of Humanity, al- though in order to reach such a terminus he was obliged to throw his original Positivism over- board and follow the subjective method. In view then of all this complicated difference be- tween the Positivist conceptionof philosophyand the conception expounded in this work, I think we are quite justified in designating our own conception by a different and characteristic name. But the most fatal and irreconcilable diver- gence appears when we come to consider the third cardinal proposition, — that which relates to deanthropomorphization. If we inquire how it was that Comte was enabled to perpetrate, in the name of philosophy, such a prodigious piece of absurdity as the deification of Humanity, we shall find the explanation to lie in his miscon- ception of what is meant by the relativity of knowledge. A good illustration of his confused thinking on this subject, to which I have al- ready had occasion to refer, is afforded by his in COSMIC PHILOSOPHY treatment of atheism. Comte had no patience with atheists, because of the chiefly negative and destructive character of the atheistic philo- sophy dominant in the eighteenth century. But when he lets us into his philosophic reasons for rejecting atheism, we find him complaining of the atheists, not because of their denial of Deity, nor because their doctrine contravenes the rela- tivity of knowledge, but because they indulge in " metaphysical attempts to explain the origin of life upon the earth's surface." ( ! ) On read- ing such passages, it becomes sufficiently evi- dent that Comte did not really understand why metaphysical inquiries are illegitimate, but re- jected them very much as the general reader might reject them, because they muddled his mind ; and we may acknowledge the justice of Professor Huxley's sarcasm, that " metaphy- sics " is with Comte a " general term of abuse for anything that he does not like." Certain it is that Comte never understood the true import of the doctrine of relativity, as it is stated in our fourth chapter, — that there exists an Unknow- able Reality, of which all phenomena, as pre- sented in consciousness, are the knowable mani- festations. As I have already observed, his most illustrious follower, M. Littre, unreservedly stigmatizes as " metaphysical " this very doctrine of the Unknowable, upon which the Cosmic Philosophy bases its rejection of metaphy- 112 COSMISM AND POSITIVISM sics. Had Comte ever understood this doc- trine, he would neither have sought to impose upon us a phenomenal God, in the form of idealized Humanity, nor would he have virtu- ally abandoned his original Positivism in the wild attempt to " regenerate " the subjective method. All these things show that Comte never really fathomed the distinction between metaphysics and science ; and as the final out- come of all this complicated misconception, we find him, in his famous " Law of the Three Stages," setting forth as the goal of all specula- tive progress a state or habitude of mind which never has existed and which never can exist. Herein the antagonism between Cosmism and Positivism becomes so fundamental as to out- weigh all minor points of agreement, even were the points of agreement ten times as numerous as they are. For since we deny that the Posi- tive mode of philosophizing, implying the re- cognition of nothing beyond the contents of observed facts, is a practicable mode at all, it is clear that we cannot, save by the utter distor- tion and perversion of human speech, be classi- fied as Positivists. Casting aside, then, our third and fourth car- dinal propositions, temporarily assumed for the purpose of emphasizing this rejection of them, we may briefly restate as follows the fundamen- tal issue between Cosmism and Positivism. vol. n 1 1 3 COSMIC PHILOSOPHY We have seen that Comte discerned the fact that there has been a continuous progress in men's conceptions, of which the chief symptom has been deanthropomorphization, and of which the result must be the destruction of ontology. He also discerned the fact, that after giving up ontology, it is still possible to build up a philo- sophy out of materials furnished by the sci- ences. We have freely admitted that, in each of these cases, the step taken by Comte was sufficient to work a revolution in the attitude of philosophy ; and we may add that, by vir- tue of this twofold advance, Comte was justi- fied in calling his system of philosophy " posi- tive," in contrast with the absolutely sceptical or " negative " philosophy of the eighteenth cen- tury. But, while admitting all this, we have also seen that Comte supposed the terminal phase of deanthropomorphization to consist in the ignoring of an Absolute Power manifested in the world of phenomena ; and that he regarded philosophy merely as an Organon of scientific methods and doctrines useful in constructing a theory of Humanity and a social Polity. On the other hand, the Cosmic Philosophy is founded upon the recognition of an Absolute Power manifested in and through the world of phenomena ; and it consists in a Synthesis of scientific truths into a Universal Science dealing 114 COSM1SM AND POSITIVISM with the order of the phenomenal manifesta- tions of the Absolute Power. And manifestly these differences between the two systems of philosophy constitute an antagonism which is fundamental and irreconcilable. If the Posi- tivist conception of philosophy be true, then the work which I am now writing is founded upon a baseless metaphysical fallacy ; and con- versely it is impossible to accept the doctrine expounded in this work, without ipso facto de- claring the main position of Positivism to be untenable. I shall hereafter have occasion to examine the views concerning Psychology, Sociology, Religion, and Practice, which are characteristic of the Positive Philosophy ; and, as heretofore, while dissenting from those views in every in- stance, I shall have no hesitation in acknow- ledging their merits or in assigning a full meed of homage to the great thinker by whom they were propounded. But while my dissent upon all these points will serve to emphasize and illustrate the fundamental dissent declared in these Prolegomena, it will not be needful again to demonstrate in detail that we are not adher- ents of the Positive Philosophy. With thrice- reiterated argument, and at the risk of wearying the reader, it has now been made sufficiently evident that Cosmism and Positivism, far from being identical or identifiable with each other, "5 COSMIC PHILOSOPHY are in a certain sense the two opposite poles of scientific philosophizing. And in virtue of this demonstrated antagonism, the divergences here- after to be signalized will appear not merely as easily intelligible but even as a priori inevitable. 116 CHAPTER XI THE QUESTION STATED WE have now accomplished our pre- liminary task of defining and illus- trating the scope and methods of Cos- mic Philosophy, and are prepared to begin the work of constructing a theory of the universe out of the elements which science can furnish. It will accordingly become necessary for us to pass in review the sciences systematized in the eighth chapter, that we may be enabled to con- template the widest truths which they severally reveal, as corollaries of some ultimate truth. In undertaking this task, there are two opposite courses, either of which we might pursue, though with differing degrees and kinds of success. On the one hand, we might begin with a survey of the concrete sciences ; and having ascertained the most general truths respectively formulated by astronomy, geology, biology, psychology, and sociology, we might interpret all these truths in common by merging them all in a single widest generalization concerning the con- crete universe as a whole ; and lastly, through an analysis of this widest generalization we 117 COSMIC PHILOSOPHY might seek the ultimate axiom by which the validity of our conclusions is certified. Or, on the other hand, we might begin by searching directly for this ultimate axiom ; and having found it, we might proceed to deduce from it that widest generalization which interprets the most general truths severally formulated by the concrete sciences ; and finally, by the help of these universal principles, we might perhaps succeed in eliciting sundry generalizations con- cerning particular groups of concrete pheno- mena which might otherwise escape our scru- tiny. The latter, or synthetic method of procedure, is much better adapted for our present purpose than the former, or analytic method. Indeed the mass of phenomena with which we are re- quired to deal is so vast and so heterogeneous, the various generalizations which we are re- quired to interpret in common are apparently so little related to one another, that it may well be doubted if the appliances of simple induction and analysis would ever suffice to bring us within sight of our prescribed goal. The history of scientific discovery affords numerous illustra-. tions — and nowhere more convincingly than in the sublime chapter which tells the triumph of the Newtonian astronomy — of the comparative helplessness of mere induction where the phe- nomena to be explained are numerous and com- 118 THE QUESTION STATED plicated. A simple tabulation and analysis of the planetary movements would never have dis- closed, even to Newton's penetrating gaze, the law of dynamics to which those movements con- form. But in these complicated cases, where in- duction has remained hopelessly embarrassed, the most brilliant success has often resulted from the adoption of a hypothesis by which the phenomena have been deductively interpreted, and which has been uniformly corroborated by subsequent inductions. The essential requisite in such an hypothesis is that it must have been framed in rigorous conformity to the require- ments of the objective method. It must be based upon properties of matter or principles of dynamics that have previously been established or fully confirmed by induction ; it must appeal to no unknown agency, nor invoke any un- known attribute of matter or motion ; and it must admit ultimately of inductive verification. Such a hypothesis, in short, is admissible only when it contains no unverifiable element. And of hypotheses framed in accordance with these rigorous requirements, the surest mark of gen- uineness is usually that they are not only uni- formly verified by the phenomena which first suggested them, but also help us to the detec- tion of other relations among phenomena which would otherwise have remained hidden from us. In conformity, then, to these requirements of 119 COSMIC PHILOSOPHY scientific method, our course is clearly marked out for us. We have first to search, among truths already indisputably established, for that ultimate truth which must underlie our Synthe- sis of scientific truths. We have next to show how the widest generalization which has yet been reached concerning the concrete universe as a whole, may be proved to follow, as an in- evitable corollary, from this ultimate truth. This widest generalization will thus appear, in the light of our demonstration, as a legitimate hypothesis, which we may verify by showing that the widest generalizations severally obtain- able in the concrete sciences are included in it and receive their common interpretation from it. Throughout the earlier part of this special verification, in which we shall be called upon to survey the truths furnished respectively by astronomy, geology, biology, and psychology, I shall follow closely in the footsteps of Mr. Spencer, who has already elaborately illustrated these truths in the light of the Doctrine of Evo- lution. When we arrive at sociology — still following Mr. Spencer's guidance, but ventur- ing into a region which he has as yet but cur- sorily and fragmentarily surveyed for us — I shall endeavour to show that our main hypo- thesis presents the strongest indications of its genuineness by affording a brilliant interpreta- tion of sundry social phenomena never before 120 THE QUESTION STATED grouped together under a general law. This interpretation I shall then seek further to verify by showing how it includes and justifies what- ever is defensible in the generalizations which such writers as Comte and Buckle have obtained from an inductive survey of the facts of human history. Finally I shall apply our central hy- pothesis to the special problem of the Origin of Man, and show how, from its marvellous success in dealing with the difficult questions of intellectual and moral progressiveness, the Doc- trine of Evolution must be pronounced to have sustained the severest test of verification which our present scientific resources enable us to ap- ply upon this great scale. With this most signi- ficant and interesting inquiry, our Synthesis of scientific doctrines will be completed. Such ulti- mate questions as must inevitably be suggested on our route — questions concerning the rela- tions of the Doctrine of Evolution to Religion and Ethics — will be considered, with the help of the general principles then at our command, in the Corollaries which are to follow. At present, however, we are not at the goal, but at the starting-point of this arduous course ; and our attention must first be directed to the search for that ultimate axiom upon which our Synthesis must rest. Where now shall we be- gin ? In what class of sciences are we to look for our primordial principle ? The above sur- 121 COSMIC PHILOSOPHY vey of our projected course has already assured us that we need not search for it among the concrete sciences. Obviously the widest pro- position which can possibly be furnished by astronomy or biology, or any other concrete sci- ence, cannot be wide enough to underlie a Syn- thesis of all the sciences. The most general theorems of biology are not deducible from the most general theorems of astronomy ; nor vice versa. But the most general theorems of each concrete science are ultimately deducible from theorems lying outside the region of concrete science. Where shall we find such theorems ? If we turn to the purely abstract sciences — logic and mathematics — we shall get but little help. Useful as these sciences are, as engines of in- vestigation, they do not contain what we are now looking for. Obviously mathematics, deal- ing only with relations of number, form, and magnitude, cannot supply the ultimate principle from which may be deduced such phenomena as the condensation of a nebula, the segmen- tation of an ovum, or the development of a tribal community. To build a system of philo- sophy upon any possible theorem of mathemat- ics would only be to repeat, after twenty-four centuries, the errors of Pythagoras. And the helplessness of abstract logic, for our purposes, is too manifest to need illustration. Let us then turn to the abstract-concrete sci- 122 THE QUESTION STATED ences ; for in the widest generalizations at which these sciences have jointly arrived we must find, if anywhere, the theorem which we desire. I say "jointly," for in the deepest sense the sub- ject-matter is the same, in molar physics, in molecular physics, and in chemistry. All three sciences deal, in one way or another, with the most general laws of those redistributions of matter and motion which are continually going on throughout the knowable universe. The first deals with the movements of masses ; the second deals with movements of molecules, and with the laws of aggregation of molecules that are homogeneous ; the third deals with the laws of aggregation of molecules that are heteroge- neous. In either case the phenomena dealt with are movements of matter, whether movements of translation through space, or movements of undulation among molecules, or movements whose conspicuous symptom is change of physi- cal state or of chemical constitution. The widest theorems, therefore, which the three abstract- concrete sciences can unite in affirming, must be universal propositions concerning Matter and Motion. Obviously it is in this region of science that we must look for our primordial theorem. But little reflection is needed to convince us that all the truths attainable by the concrete sciences must ultimately rest upon truths relating to 123 COSMIC PHILOSOPHY the movements of matter. It is with the move- ments, actual or inferred, of certain specific masses of matter, that astronomy in both its branches is concerned. Movements of matter, likewise, in a specific region of the universe, and under specific conditions characteristic of this region, constitute the facts about which geology speculates. We need but remember that nutrition is at bottom merely a process in which certain molecules shift their positions, and that the life of an organism is simply a long- continued series of adjustments and readjust, ments among mutually related and mutually influencing systems of aggregated molecules, in order to see that the fundamental laws of the movements of matter must underlie biology also. And although the phenomena of mind — whether manifested in individuals or in commu- nities — cannot be explained as movements of matter ; yet, as will be hereafter shown, there is no mental phenomenon which does not involve, as its material correlate, some chemical change in nerve-tissue consisting in a redistribution of molecules ; so that in psychology and sociology likewise, our conclusions must become ulti- mately implicated with theorems concerning matter and motion. Thus in every department of concrete science, the leading problem is in some way or other, either directly or indirectly or very remotely, concerned with distributions 124 THE QUESTION STATED and redistributions of matter and motion ; and in all our specific conclusions some general con- clusion relating to movements of matter must be directly or indirectly or very remotely in- volved. Our course is thus still more definitely marked out. We must first search for the deepest attainable truth respecting matter and motion abstractly considered. We must pursue this truth and its corollaries, among the most general groups of phenomena in which these corollaries are exemplified, until we arrive at some concrete result concerning the most gen- eral aspects of that redistribution of matter and motion which is everywhere going on. And upon this concrete result we shall find that uni- versal generalization to be based, the validity of which we have afterwards to certify by its agreement with inductions drawn from the sev- eral groups of phenomena with which the con- crete sciences deal. Here, before proceeding further*, we may fitly pause for a moment, to relieve a puzzling doubt which may ere this have disturbed the mind of the reader. Did we not elaborately prove, in our 6pening chapter, that concerning the move- ments of molecules and their aggregation into masses, not only nothing can be known, but no tenable hypothesis can be framed ? Did we not, with full knowledge of what we were doing, hang 125 COSMIC PHILOSOPHY up as the very sign-board of our fypovTicrrripiov or philosophy - shop, the proposition that all that either sense or reason can tell us concern- ing the intimate structure of a block of wood is utterly and hopelessly delusive ? Did we not show that the hypothesis of attractive and re- pulsive forces lands us straightway in an insolu- ble contradiction ? Did we not find it impossi- ble to get rid of the difficulties which surround the conception of an atom or a molecule, whether regarded as divisible or as indivisible ? And did we not conclude that the conception of matter acting upon matter is a pseud-concep- tion which can by no effort be construed in con- sciousness ? — Yet in spite of all this, it may be said, we are about to base the entire following Synthesis upon preliminary conclusions relating to the movements of molecules and their aggre- gation into masses ; we are likely to draw infer- ences from the assumed intimate structure of certain bodies ; we have inevitably to make use of the hypothesis of attractive and repulsive forces ; we shall constantly have tacit reference to the conception of atoms and molecules ; and we shall be obliged to take account of matter as constrained in its movements by other neigh- bouring matter. Is there not here, it may be asked, a reductio ad ahurdum, either of the Syn- thesis which is to follow, or of the initial argu- ments upon which the claims of such a Synthesis 126 THE QUESTION STATED to stand for the whole of attainable philosophy were partly based ? I state this dilemma as strongly as possible, because it forcibly illustrates the omnipresence of Mystery, — because it shows how, beneath every physical problem, there lies a metaphy- sical problem whereof no human cunning can de- tect the solution. Practically, however, the ave- nue of escape has sometime since been implicitly indicated, — in the fifth and sixth chapters of these Prolegomena. In the chapter on Causation it was shown that, though we can in nowise con- ceive matter as acting upon matter, yet, for the purposes of common-sense, of science and of philosophy, it is quite enough that one kind of phenomenal manifestation is invariably and un- conditionally succeeded by some other kind of phenomenal manifestation. And in characteriz- ing the Subjective and Objective Methods, we saw that the truth of any proposition, for scien- tific purposes, is determined by its agreement with observed phenomena, and not by its con- gruity with some assumed metaphysical basis. For example, the entire Newtonian astronomy — the most elaborate and finished scientific achievement of the human mind — rests upon a hypothesis which, if metaphysically inter- preted, is simply inconceivable. The conception of matter attracting matter through an inter- vening tract of emptiness is a conception which 127 COSMIC PHILOSOPHY it is impossible to frame, — and Newton knew it, or felt it to be so. But nowhere did his un- rivalled wisdom show itself more impressively than in this, — that he accurately discriminated between the requirements of science and the re- quirements of metaphysics, and clearly saw that, while metaphysics is satisfied with nothing short of absolute subjective congruity, it is quite enough for a scientific hypothesis that it gives a correct description of the observed coexist- ences and sequences among phenomena.1 In truth, for scientific purposes, we are no more required to conceive the action of matter upon matter in the case of gravitation than in any other case of physical causation. All that the hypothesis really asserts is that matter, in the presence of other matter, will alter its space relations in a specified way ; and there is no re- ference whatever to any metaphysical occulta vis which passes from matter in one place to matter in another place. There is, however, no good ground for ob- jecting to the use of the phrase " attraction," provided it be employed only as a scientific artifice. There is a certain sense in which sci- 1 This is distinctly stated by Copernicus : " Neque enim necesse est eas hypotheses esse veras, imo ne verisimile quidem, sed sufficit hoc unum, si calculum observationibus congruentem exhibeant." See Lewies, Aristotle, p. 92 ; Problems of* Life and Mind, vol. i. p. 317. 128 THE QUESTION STATED ence, as well as legal practice, has its " fictions " that are eminently useful. The lines and circles with which geometry deals have nothing answer- ing to them in nature ; and the analyst employs a " scientific fiction " when he deals with in- finitesimals, since it is impossible to conceive a quantity less than any assignable quantity. In like manner, there is nothing objectionable in using language which assimilates the case of a planet revolving about the sun to the case of a stone whirled at the end of a string ; for there is real similarity between the phenomena. So if the science of chemistry had been obliged to wait until all the metaphysical difficulties which encompass the conception of a molecule or an atom had been cleared away, it might well have waited until the end of the world. Quite likely the " atom " in chemistry is as much a " scien- tific fiction " as the " infinitesimal " in algebra ; but we cannot therefore complain of the chemist for assigning to it shape and dimensions, pro- vided he makes a scientific and not a metaphy- sical use of the artifice. In the region of science such a fiction is no more illegitimate than that fiction in the region of common-sense by which I judge this writing-table to be solid, while, for aught I know to the contrary, the empty spaces between its particles may be as much greater than the particles as the interstellar spaces are greater than the stars. We need have no hesi- vol.ii 129 COSMIC PHILOSOPHY tation, therefore, in dealing with the aggrega- tions of atoms and molecules, after the manner of the chemical philosopher, or with attractive and repulsive forces, after the manner of the physicist, so long as we take care that the sub- stance of our propositions has reference only to verifiable coexistences and sequences among phenomena. Another possible difficulty may be now more summarily disposed of. If it be urged that to frame a "generalization concerning the concrete universe as a whole " is manifestly to transgress the limits of sound philosophizing, since we can never know but a tiny portion of the concrete universe, and can never even know how much there is that lies beyond our ken ; if such an ob- jection be urged against the undertaking planned in the present chapter, we may again appeal to Newton as witness in our favour. The law of gravitation is expressed in terms that are strictly universal, — terms which imply that wherever matter exists, be it a million times more remote than the outermost limit of telescopic vision, the phenomena of gravitation must be mani- fested. Comte, indeed, questioned the legiti- macy of extending the generalization beyond the limits of the solar system. But his doubt, which facts so soon refuted, was based on in- adequate knowledge of the psychological aspect of the case. Newton's hypothesis simply de- 130 THE QUESTION STATED tected and generalized the mode of manifestation of one of those properties by virtue of which matter is matter ; and he was justified, according to the principles laid down in our third chapter, in basing a universal proposition upon a single instance. The final test of the presence of mat- ter is the manifestation of the gravitative tend- ency ; and such must be the case so long as we are unable to transcend experience. As I before observed, it is quite possible that there may be worlds in which numerical limitations like ours are not binding, and so it is very possible that there may be worlds in which there is nei- ther matter nor gravity. But any such possible worlds, standing entirely out of relation to our experience, are practically non-existent for a phi- losophy which is based on the organization of experience. Now, though the law of evolution is not, like the law of gravitation, the generalization of a property of matter, it is still the generalization of certain concrete results of known properties of matter. And the universality which in the following chapters will be claimed for this gen- eralization is precisely like the universality claimed for the law of gravitation. The law of evolution professes to formulate the essential characteristics of a ceaseless redistribution of matter and motion that must go on wherever matter and motion possess the attributes by 131 COSMIC PHILOSOPHY which we know them. In Mr. Mill's hypo- thetical world where two and two make five, the law of evolution may not hold sway. But within the limits of our experience, the law is a " generalization concerning the concrete uni- verse as a whole ; " and if it be satisfactorily verified, we shall have achieved that organiza- tion of scientific truths into a coherent body of doctrine which has been shown to be the legi- timate aim of Philosophy. Here in conclusion we may again call atten- tion to the significance of the phrase by which I have designated the kind of philosophy that is expounded in this work. We may reiterate the statement, which has already been illustrated from various points of view, that our philosophy is peculiarly entitled to the name of Cosmic Phi- losophy. For while it may be urged that earlier philosophies have also been cosmic, in so far as they have sought to offer some explanation of the universe, on the other hand it must be ac- knowledged that never before has the business of philosophy, regarded as a theory of the uni- verse, been undertaken with so clear and dis- tinct a conception of its true scope and limi- tations. Though other thinkers, before Mr. Spencer, may have generalized about the con- crete universe as a whole, it cannot be denied that he has been the first to frame a verifiable hypothesis upon this stupendous scale. The 132 THE QUESTION STATED law of evolution is the first generalization con- cerning the concrete universe as a whole, which has been framed in conscious conformity to the rigorous requirements of the objective method, and which has therefore served to realize the prophetic dream of Bacon, by presenting Phi- losophy as an organism of which the various sciences are members. Obviously a system which has achieved, or consciously sought to achieve, such a result, is entitled par excellence to the name of Cosmic Philosophy. It has been the first to give practical realization to that sublime thought of two master minds, which I have inscribed at the head of this work : — " To a thinker capable of comprehending it from a single point of view, the universe would present but a single fact, but one all-compre- hensive truth ; and it is for this reason that we call it Cosmos, and not chaos." *33 PART II SYNTHESIS "Je unvollkommener das Geschopf ist, desto mehr sind diese Theilc einander gleich oder ahnlich, und desto mehr gleichen sie dem Ganzen. Je vollkommener das Geschopf wird, desto unahnlicher werden die Theile einander. Je ahnlicher die Theile einander sind, desto weniger sind sie einander subordinirt. Die subordination der Theile deutet auf ein vollkomm- neres Geschopf." — Goethe, Zur Morphologic. 1807. CHAPTER I MATTER, MOTION, AND FORCE1 IN the third book of the " Philosophic Posi- tive," Comte observes that it can hardly be by accident that the word " Physics," which originally denoted the study of the whole of nature, should have become restricted to that science which deals with the most abstract and general laws of the rearrangement of Matter and Motion. This is one of the many profound re- marks scattered through Comte's writings, the full significance of which he could hardly him- self have realized.^ For it will now appear — as the preceding chapter taught us to expect — that the study of Physics (including under that name, 1 [See Introduction, § 1 5. J a For immediately afterwards we find Comte basing the organic sciences upon physics, but excluding astronomy, which he calls an " emanation from mathematics." It is indeed dif- ficult to see how astronomy, which involves the physical ideas of matter, motion, and force, can be an emanation from mathematics, which involves only the purely abstract ideas of space and number. In fact, as above shown (Part I. chap, viii.), astronomy, no less than the other concrete sciences, is dependent upon physics. Here, as elsewhere, Comte was mis- led by his serial arrangement. l37 COSMIC PHILOSOPHY for the moment, the three abstract-concrete sci- ences) underlies the study of the whole of nature, and discloses those universal truths upon which a Synthesis of the widest truths disclosed by the concrete sciences must repose. It investigates the general phenomena of matter, motion, and force ; while the concrete sciences investigate these phenomena as manifested in particular groups of aggregates. The primordial axiom, upon which our synthetic study of the universe must be founded, is one which is disclosed by the analytic study of the movements of masses and molecules. And thus the threefold classi- fication of the sciences, by which we found it necessary to replace the simple linear classifica- tion of Comte, will find itself practically justi- fied in the very first step which we take toward the organization of scientific truths into a sys- tem of Cosmic Philosophy. For at the bottom alike of molar physics, of molecular physics, and of chemistry, there lie, in fact, two universal propositions, — the one relating to Matter, the other relating to Mo- tion. These are the familiar propositions that Matter is indestructible •, and that Motion is con- tinuous. Upon the truth of this pair of closely related propositions depends the validity of every conclusion to which chemistry or either branch of physics can attain. If, instead of dealing with unalterable quantities and weights, 138 MATTER, MOTION, AND FORCE the chemist and physicist " had to deal with quantities and weights which were apt, wholly or in part, to be annihilated, there would be introduced an incalculable element, fatal to all positive conclusions." And since motions of masses and molecules form a principal part of the subject-matter of the three abstract-concrete sciences, it is obvious that " if these motions might either proceed from nothing or lapse into nothing, there would be an end to scientific in- terpretation of them ; " no science of chemis- try, or of physics, molecular or molar, would be possible. The evidence which has secured universal acceptance for these twin theorems has been chiefly inductive evidence. The ancients freely admitted that matter might be created and de- stroyed ; and until the time of Galileo it was supposed that moving bodies had a natural tendency to lose their motion by degrees until they finally stopped. Falsifying many of the complex conditions in the case, the ancients verbally maintained the negations of the theo- rems that matter is indestructible and motion continuous ; although, if they had tried to real- ize in thought their crude propositions, they would have found it impossible. But gradually it began to be perceived that in all cases where matter disappears — as in the burning of wood or the evaporation of water — the vanished *39 COSMIC PHILOSOPHY matter has only undergone a molecular change which renders it temporarily imperceptible by our unaided senses. Of the manner in which quantitative chemistry has demonstrated this truth, pursuing, balance in hand, the vanished matter through all its protean transformations, it is unnecessary to speak. Similar has been the evidence in the case of motion. Observ- ing that, the more effectually friction, atmos- pheric resistance, and other obstacles to the vis- ible continuance of motion are eliminated, the longer the motion continues, the conclusion was reached, by the method of concomitant va- riations, that if all obstacles could be eliminated, the motion would continue forever. Finally, when it was shown that the apparent loss of motion caused by friction is, in fact, only a transformation of a certain quantity of molar motion into its equivalent quantity of that spe- cies of molecular motion known as heat, it was admitted on all sides that motion is indestruc- tible, as welt as matter. But a brief analysis will show that the twin theorems which we are considering have a de- ductive warrant equally valid with their induc- tive warrant. Deep as are the truths that mat- ter is indestructible and motion continuous, there is a yet deeper truth implied by these two. These theorems are not fundamental, but de- rivative ; and it therefore becomes necessary to 140 MATTER, MOTION, AND FORCE ascertain the axiom upon which they depend, since here, if anywhere, must be found the pri- mordial truth which we are seeking. Since we cognize any portion of matter what- ever only as an aggregate of coexistent posi- tions which offer resistance to our muscular energies ; since it is primarily by virtue of such resistance that we distinguish matter from empty space ; it follows that our idea of matter is built up of experiences of force, and that the inde- structible element in matter is its resisting power, or the force which it exerts. Considering different portions of matter in their relations to each other, we are brought to the same conclu- sion. When we say that it is chemistry which has proved with the balance that no matter is ever annihilated, we imply that the test of the presence of matter is gravitative force, and that this force is proportional to the quantity of matter. The case of motion is precisely similar. We cognize motion as the successive occupation of a series of positions by an aggregate of coexist- ent positions which offer resistance ; and the essential element in the cognition — " the ne- cessity which the moving body is under to go on changing its position " — has been proved to result from early experiences of force as mani- fested in the movements of our muscles. Con- sequently, as Mr. Spencer observes, when we HI COSMIC PHILOSOPHY find ourselves compelled to conceive motion as continuous, we find that what " defies suppres- sion in thought is really the force which the motion indicates. The unceasing change of position, considered by itself, may be mentally abolished without difficulty. We can readily imagine retardation and stoppage to result from the action of external bodies. But to imagine this is not possible without an abstraction of the force implied by the motion. We are obliged to conceive this force as impressed in the shape of reaction on the bodies that cause the arrest." 1 Or to put the whole case briefly in another form : The fundamental elements of our con- ception of matter are its force-element and its space-element, namely, resistance and extension. The fundamental elements of our conception of motion are its force-element and its space- and-time-element, namely, energy and velocity. That in each case the force-element is primor- dial is shown by the facts that what we cannot conceive as diminished by the compression of matter is not its extension but its power of re- sistance ; what we cannot conceive as diminished by the retardation of motion is not its velocity but its energy. Therefore, in asserting that matter is inde- structible and that motion is continuous, we assert, by implication, that fo^ce is persistent. 1 [First Principles, § 59.] 142 MATTER, MOTION, AND FORCE Our two fundamental theorems are thus seen to derive their validity from a yet deeper the- orem, — the proposition that the force mani- fested in the knowable universe is constant, can neither be increased nor diminished. To this result, which we have here obtained through a general consideration of the problems treated by the abstract - concrete sciences, we shall be equally led by any special question of molar physics, molecular physics, or chemistry which we may choose to analyze. When we say that the curve described by a cascade in leaping from a projecting ledge of rock is a parabola of which the coordinates express respectively the momentum of the water and the intensity of gravity at the verge of the ledge ; or when we say that the line followed by any solid body, drawn by two differently situated forces, is the diagonal of a parallelogram of which the sides express the respective intensities of the forces ; the validity of our assertion depends entirely upon the postulate that the forces in question are constant in amount. Annihilate a single unit of force, and our proposition is hopelessly falsified. Similarly in molecular physics, when we enunciate the formula by means of which Joseph Fourier founded the mathematical theory of heat — namely, the formula that, in all cases of radiation and conduction, the thermological action between two bodies is proportional to 143 COSMIC PHILOSOPHY the difference of their temperatures — we imply that action and reaction are always equal be- tween the systems of molecules which compose the two bodies. And the equality of action and reaction between systems of atoms is taken for granted in every proposition of chemistry ; as, for instance, when we say that it will take four molecules of any monatomic substance, like hydrogen, to saturate a single molecule of any tetratomic substance, like carbon. Now to as- sert the equality of action and reaction, whether between masses, molecules, or atoms, is to as- sert that force is persistent. " The allegation really amounts to this, that there cannot be an isolated force, beginning and ending in nothing ; but that any force manifested, implies an equal antecedent force from which it is derived, and against which it is a reaction. Further, that the force so originating cannot disappear without result ; but must expend itself in some other manifestation of force, which, in being produced, becomes its reaction ; and so on continually." * Clearly, therefore, the assertion that force is per- sistent is the fundamental axiom of physics : it is the deepest truth which analytic science can disclose. But now what warrant have we for this fun- damental axiom ? How do we know that force is persistent ? If force is not persistent, if a sin- 1 Spencer, First Principles, p. 1 88. 144 MATTER, MOTION, AND FORCE gle unit of force can ever be added to or sub- tracted from the sum total at any moment ex- isting, our entire physical science is, as we have seen, a mere delusion. In such case, it is a de- lusion to believe that action and reaction are always equal, that the strongest bow, bent by the strongest muscles, will always send its arrow to the greatest distance if otherwise unimpeded — it is a delusion to believe that the pressure of the atmosphere and its temperature must always affect the height of enclosed columns of alcohol or mercury, or that a single molecule of nitrogen will always just suffice to saturate three molecules of chlorine. And this being the case, our concrete sciences also fall to the ground, and our confidence in the stability of nature is shown to be baseless ; since for aught we can say to the contrary, the annihilation of a few units of the earth's centrifugal force may cause us to fall upon the sun to-morrow. But how do we know that all science is not a delusion, since there still exist upon the earth's surface persons who will tell us that it is so ? Why do we so obstinately refuse to doubt the constancy of the power manifested in nature ? What proof have we that no force is ever cre- ated or destroyed ? Logically speaking, we have no proof. An axiom which lies below all framable proposi- tions cannot be deductively demonstrated. Be- vol. n. *45 COSMIC PHILOSOPHY low the world stands the elephant on the back of the tortoise, and if under the tortoise we put the god Vishnu, where is Vishnu to get a foot- hold ? Nor can our axiom be demonstrated in- ductively, without reasoning in a circle. We can- not adduce the observed equality of action and reaction in proof of the persistence of force, because this persistence is taken for granted in every observation by which the equality of ac- tion and reaction is determined. Obviously it is impossible to prove the truth of an axiom by any demonstration in every step of which the truth of the axiom must be assumed. But these results need not surprise or disturb us. As we saw, when discussing the Test of Truth, the process of demonstration, which con- sists in continually " merging derivative truths in those wider and wider truths from which they are derived," must eventually reach a widest truth, which cannot be contained in or derived from any other. At the bottom of all demon- stration there must lie an indemonstrable axiom. And the truth of this axiom can only be certi- fied by the direct application of the test of in- conceivability. We are compelled to believe in the persistence of force, because it is impossible to conceive a variation in the unit by which force is measured. It is impossible to conceive something becoming nothing or nothing becom- ing something, without establishing in thought 146 MATTER, MOTION, AND FORCE an equation between something and nothing ; and this cannot be done. That one is equal to zero is a proposition of which the subject and predicate will destroy each other sooner than be made to unite. Thus the proof of our fundamental axiom is not logical, but psychological. And, as was formerly shown, this is the strongest possible kind of proof. Inasmuch as our capacity for conceiving any proposition is entirely depend- ent upon the manner in which objective expe- riences have registered themselves upon our minds, our utter inability to conceive a variation in the sum total of force implies that such vari- ation is negatived by the whole history of the intercourse between the mind and its environ- ment since intelligence first began. The incon- ceivability test of Kant and the experience test of Hume, when fused in this deeper synthesis, unite in declaring that the most irrefragable of truths is that which survives all possible changes in the conditions under which phenomena are manifested to us. The persistence of force, therefore, being an axiom which survives under all conditions cognizable by our intelligence, being indeed the ultimate test by which we are compelled to estimate the validity of any pro- position whatever concerning any imaginable set of phenomena and under any conceivable circumstances, must be an axiom necessitated by H7 COSMIC PHILOSOPHY the very constitution of the thinking mind, as perennial intercourse with the environment has moulded it. Mr. Mill, indeed, in his " System of Logic," Book III. chapter xxi., maintains that our belief in the necessity and universality of causation (which was above shown J to be an immediate corollary from the persistence of force) rests upon an induction per enumerationem simplicem, which is, however, valid in this one case, be- cause it is coextensive with all known orders of phenomena. The incompleteness of this view is shown by the fact that the persistence of force is necessarily assumed in every step of the vast induction by which the law of causation is said to be established. Mr. Mill only emphasizes the incompleteness of his view when he repudi- ates the inconceivability test as evidence of the law in question. This point has been already so fully discussed that little more need to be said about it here. When, in a future chapter, we come to deal especially with the evolution of intelligence, we shall see that Mr. Mill's inade- quate treatment of this subject is due to im- perfect mastery of the Doctrine of Evolution. We shall see that the so-called experience phi- losophy is both wider and deeper than Eng- lish psychologists, from Hobbes to Mill, have imagined. We shall see that not only our ac- 1 See above, Part I. chap. vi. 148 MATTER, MOTION, AND FORCE quired knowledge, but even the inherited consti- tution of our minds, is the product of accu- mulated and integrated experiences, partly per- sonal but chiefly ancestral. Upon this wider ground we shall find ourselves able to dwell in peace with our old foes, the intuitionalists, since it will be seen that the very intuitions upon which they rightly insist as inexplicable from individual experience are nevertheless explicable from the organized experiences of countless gen- erations. And the conclusion will then assert itself, with redoubled emphasis, that the axiom of the persistence of force, being the product of the entire intercourse between subject and object since the dawn of intelligence, must have the highest warrant which any axiom can have. Let us for the present, however, content our- selves with reproducing the psychological argu- ment by which Mr. Spencer clinches his demon- stration of the necessity which we are under to conceive of force as persistent. " The inde- structibility of matter and the continuity of mo- tion we saw to be really corollaries from the impossibility of establishing in thought a rela- tion between something and nothing. What we call the establishment of a relation in thought is the passage of the substance of conscious- ness from one form into another. To think of something becoming nothing would involve that this substance of consciousness, having just 149 COSMIC PHILOSOPHY existed under a given form, should next assume no form ; or should cease to be consciousness. And thus our inability to conceive matter and motion destroyed is our inability to suppress consciousness itself. What is thus proved true of matter and motion is a fortiori true of the force out of which our conceptions of matter and motion are built." Thus we see it is the persistence of consciousness itself which imposes on us the necessity of asserting the persistence of force. And accordingly this primordial axiom being involved in every act of conscious think- ing, and being the basis of experience, " must be the basis of any scientific organization of ex- periences. To this an ultimate analysis brings us down ; and on this a rational synthesis must build up." The force of these considerations will become still more strikingly apparent as we proceed to contemplate the most general corollaries of this fundamental axiom with which the science of physics has furnished us. The first of these corollaries is the theorem that the relations among forces are persistent. That is to say, in all cases an aggregate of like causes will be fol- lowed by an aggregate of like effects. " If in any two cases there is exact likeness not only between those most conspicuous antecedents which we distinguish as the causes, but also be- tween those accompanying antecedents which 150 MATTER, MOTION, AND FORCE we call the conditions, we cannot affirm that the effects will differ, without affirming either that some force has come into existence or that some force has ceased to exist. If the cooperative forces in the one case are equal to those in the other, each to each, in distribution and amount, then it is impossible to conceive the product of their joint action in the one case as unlike that in the other, without conceiving one or more of the forces to have increased or diminished in quantity ; and this is conceiving that force is not persistent." 1 It follows, therefore, from the persistence of force, that there is an invariable order of succession between the totality of phe- nomena which exist at any given instant and the totality of phenomena which exist at the next succeeding instant. No matter how many spe- cial orders of sequences may interlace to form the grand web of sequent phenomena, the order of sequences, both separately and in the ag- gregate, must be invariable. In complicated mechanical problems, where many forces are involved, we proceed to eliminate one after an- other by means of the principle of the parallel- ogram of forces, until at last we retain but two differently located forces, the resultant of which is easily calculable. So, in the most complex cases of causation to be found in nature — as, for instance, in those concerned in the develop- 1 First Principles, p. 193. *5* COSMIC PHILOSOPHY ment of the moral character of individuals — if we possessed the means of measuring quantita- tively the ratio of each set of antecedents to its set of consequents, we might eliminate one group after another, until at length a necessary relation of sequence would be disclosed between the resultant group of antecedents and conse- quents. As Mr. Mill observes : " For every event there exists some combination of objects or events, some given concurrence of circum- stances, positive and negative, the occurrence of which is always followed by that phenome- non. We may not have found out what this concurrence of circumstances may be ; but we never doubt that there is such a one, and that it never occurs without having the phenomenon in question as its effect or consequence." * Our unhesitating assurance that " there is a law to be found if we only knew how to find it" is thus the foundation of all the canons of induc- tive logic. The uniformity of the laws of na- ture is elsewhere called by Mr. Mill " the major premise of all inductions." The present analy- sis further shows us that this uniformity of law is resolvable into the persistence of relations among forces, and is therefore an immediate corollary from the persistence of force. Besides this purely philosophical corollary from our fundamental axiom, we have to note 1 System of Logic, 6th edition, vol. i. p. 367. 152 MATTER, MOTION, AND FORCE three other corollaries, which — as belonging to the transcendental regions of physical science — must be set forth and illustrated before we can profitably begin our synthesis of scientific truths. Let us briefly consider these in their natural order. The first of these corollaries is the generali- zation currently known as the " Correlation of Forces." Since each manifestation of force must have been preceded by some other equivalent manifestation of force, it follows that when any specific manifestation appears to terminate, it does not really cease to exist, but is only transformed into some other specific manifes- tation. That we may better apprehend this important truth, let us clear away some of the ambiguity which surrounds the terms commonly employed in the statement of it. The phrase "correlation of forces," which means the corre- lation of sensible motion with heat, light, elec- tricity, etc., implies that heat, light, and electri- city are forces. This is not strictly accurate. Heat and light are modes of undulatory motion, and electricity, with its kindred phenomena, is to be similarly interpreted. Now motion is not force, but one of the manifestations of force ; and so the various modes of motion, molar and molecular, are differently conditioned manifes- tations of force. The force which produces or lS3 COSMIC PHILOSOPHY resists motion is known by us only under the twofold form of attraction and repulsion, which may be either polar or universal. Polar attrac- tion or repulsion is that which acts with differ- ent power in different directions. An example of polar attraction is to be found in every case of crystallization, where molecules are grouped into a solid figure bounded by plane surfaces ; and a familiar example of polar repulsion is that which is exhibited when the positive poles of any two magnets are brought into mutual proximity. Universal attraction or repulsion is that which acts with equal power in all direc- tions. In universal attraction we are accustomed to distinguish three modes, respectively called gravity, cohesion, and chemism or chemical affinity. The essential difference between these modes of primary force and the various modes of motion is illustrated by the familiar facts that gravity causes molar motion while molar mo- tion does not cause gravity ; and that chemism gives rise to the species of molecular motion called heat, while heat cannot give rise to chem- ism, though it may result in a molecular rear- rangement which will allow chemism to manifest itself. For example, gravity causes a spent rocket to fall to the ground ; but the upward motion of the rocket does not cause gravity, although it results in a position of the rocket which en- •54 MATTER, MOTION, AND FORCE ables gravity to reveal itself by causing down- ward motion. So when nitrous oxide is decom- posed into nitrogen and oxygen, a considerable amount of heat is evolved ; but when all this thermal undulation is restored under appro- priate conditions, and the compound is again formed, it is not that the thermal undulation gives rise to the chemism which draws the atoms of nitrogen and oxygen together ; it is only that the thermal undulation results in such a redistribution of the atoms that their progress toward each other is unimpeded, and thus the latent force of chemism is revealed. Now the law of the correlation of forces, which perhaps ought rather to be called the law of the transformation of motion, is simply the obverse of that corollary from the persistence of force, .which affirms that whatever energy has been expended in doing work must reappear as en- ergy. The energy of molar motion which dis- appears when an arrow sticks in its target is really transformed into the energy of molec- ular motion which is recognized partly as heat and partly as electricity. That the different modes of motion are transformable into each other is now one of the commonplaces of phy- sical science, and needs but little illustration here. What is called the arrest of motion by friction is now known to be the change of molar motion into heat, when the rubbing substances J55 COSMIC PHILOSOPHY are alike in constitution, — into heat and elec- tricity, when they are unlike. In violent colli- sions, as in the chipping of stones with a mason's chisel, the arrested molar motion is partially changed into light. And when an iron bar is suspended in the magnetic meridian and vio- lently struck or continually jarred, a portion of the arrested motion reveals itself as magnetism. The transformation of heat into molar mo- tion may be seen in the rise and fall of the mer- cury in the thermometer, or in the driving of a piston by the molecular dilatation of aque- ous vapour. When lime is introduced into an atmosphere of burning hydrogen, we see the conversion of heat into light. And when the heated ends of zinc and copper wires are brought together, we see heat generating electric cur- rents. Conversely, electricity conducted down a lightning-rod is partly converted into heat ; and in the bright flashes which are followed by claps of thunder, we witness electric energy partly consumed in originating light. The phenomenon commonly called light is but a species of a mode of solar energy which may be called radiance or actinism, and which, according to the manner in which it affects our senses, is known as radiant heat, as light, or as the energy which works changes in the da- guerreotype-plate and in the leaves of plants. The difference between the higher rays of the i56 MATTER, MOTION, AND FORCE solar spectrum, which manifest themselves chiefly in causing chemical changes, and the lower rays, which are cognized as violet light, is genericallv the same as the difference between these and the still lower rays which are cog-' nized as indigo, blue, green, yellow, orange, or red light ; and the same is true if we descend to those still lower rays which are recognized only by their thermal effects. If we call the energy manifested in the solar beam by the general name of actinism, we may say that ac- tinism is transformable into all the other modes of motion. In Mr. Grove's celebrated experi- ment, where a daguerreotype-plate is ingen- iously connected with a galvanometer, a gridiron of silver wire, and a heat-registering helix, and where actinism is the initial mode of motion, there are obtained " chemical action on the plate, electricity in the wires, magnetism in the coil, heat in the helix, and [molar] motion in the needles." In all cases where the disappearance of any given mode of motion is followed by the ap- pearance of some other mode, the proof that there has been an actual transformation of the former mode into the latter is of two kinds. Deductive proof is furnished by the fact that the only alternative supposition is unthinkable, — namely, the supposition that the one kind of motion has been annihilated, while the other »57 COSMIC PHILOSOPHY kind has been created for the occasion. Induc- tive proof is furnished by the fact that wherever it is possible to measure both the amount of motion that disappears and the amount that ap- pears in its place, the two quantities are always found to be equal. Thus the molar motion im- plied in the fall of 772 pounds* of matter through one foot of space will always raise the tempera- ture of a pound of water just one degree of Fahrenheit. And similar quantitative correla- tions have been established among other modes of motion. The second corollary from the persistence of force asserts that the direction of motion in any case is always the resultant between the lines representing respectively the greatest trac- tion and the least resistance exerted by the forces upon which the motion depends. In any plexus of forces whatever, the resultant of all the tractive forces involved will be the line of greatest traction ; the resultant of all the resist- ing forces will be the line of least resistance ; and the direction of motion in the resultant of this final pair of resultants follows directly from the persistence of force. For the last resultant represents the direction and amount of a sur- plus force which remains after all the other forces have been equilibrated ; and to assert that this force will not be manifested in motion 158 MATTER, MOTION, AND FORCE along this line is to assert that force may be expended without effect. Still more obvious does this become, when we remember that " our only evidence of excess of force is the movement it produces." Since we know force not in itself, but only as revealed to conscious- ness in matter and motion, it follows that mo- tion in any direction is the only proof we have that there is a surplus of unantagonized force acting in that direction. So that our theorem becomes almost an identical proposition. But if we ask why the greater of two opposing forces is that which causes motion in its own direction, there can be no answer save the one already given. There is no warrant save the conscious- ness that the unneutralized surplus of force can- not cease to act. The simplest case contemplated by this cor- ollary is that of a moving body left to itself. There being here no force involved, save the body's own momentum, the direction of motion is an infinite straight line. But since the reali- zation of such a case would involve the annihi- lation of all matter save the body in question, it is obvious that no such simple case can ever have existed within the limits of the knowable universe. The simplest case of motion which can come within our cognizance is really com- plex to a degree which baffles computation. Mr. Spencer somewhere remarks that when a *59 COSMIC PHILOSOPHY man appears to be walking westward, he is really being carried eastward by the earth's rotation at the rate of iooo miles an hour. Besides this, the earth's orbital motion is carrying him west- ward at the differential rate of 67,000 miles an hour. Meanwhile the motion of the solar sys- tem toward the constellation Hercules is all the time bearing him in a direction neither east nor west. While, if we could comprehend in a sin- gle view the dynamic relations of the entire sidereal universe, we should find that even the enormous factors already taken into the account would help us but little toward determining the resultant direction in which the man is moving. The comparative ease with which astronomy ascertains the direction of the motions with which it deals is due to our ability to isolate ourselves theoretically from an indefinitely ex- tended universe of environing bodies; and this is due to the principle, established by Galileo, that the relative motions of the parts of an ag- gregate are not affected by the motion of the whole. If we could include in the problem the entire knowable universe, we should doubtless find the real motions of a planet as impossible to calculate mathematically as are now the mo- tions of a corpuscle of nerve-substance when thrown out of equilibrium by an act of thinking. Nevertheless because of this principle that the relative motions of parts may be calculated 160 MATTER, MOTION, AND FORCE independently of the motion of the whole, we are enabled legitimately to restrict our views, so that motion along the resultant of two or three forces may be determined and predicted with a near approach to accuracy. Witness the ease with which we can calculate the orbit of a comet. But when the forces become more numerous, it becomes impossible to determine their resultant. Witness the excessive difficulty of predicting the direction of currents in the atmosphere. The movements of organisms still more hopelessly baffle our powers of calculation. It is hardly probable that science will ever ob- tain equations for the motions of a lion in se- curing his prey ; yet that would be a very shal- low philosophy which should seek to assure us that each one of those motions does not take place along the resultant of all the forces in- volved. To an intelligence sufficiently vast, the motions of the earth in space would doubtless seem as complicated as those of the lion seem to us. But no amount of complexity can alter the fundamental principle that the direction of motion must be the resultant between the lines of greatest traction and of least resistance. In conclusion let us observe that in many cases the total amount of traction is so small compared to the total amount of resistance, that for practical purposes it may be neglected ; and vice versa. Thus, when a meteor falls upon the TOL II i£j COSMIC PHILOSOPHY earth, we may neglect the resistance of the at- mosphere, and say that the meteor follows the line of greatest traction ; and when a volcano throws up a column of lava, we may neglect the effects of gravity, and say that for the time being the lava follows the line of least resist- ance. We shall thus, without any considerable inaccuracy, avoid cumbrous verbiage ; and in the case of molecular motions propagated through masses of matter, with which our exposition is chiefly concerned, it is sufficiently accurate to say that motion follows the line of least resist- ance. 162 CHAPTER II RHYTHM THE third corollary from the persistence of force may best be introduced by a reconsideration of the simplest case of motion contemplated by the preceding corol- lary. The realization of Galileo's first law of motion — the law that a moving body must for- ever continue in a straight line with uniform velocity — obviously postulates the non-exist- ence of any other matter than that contained in the body in question. If there were but one body in the universe, that body, when once set in motion, would never alter its direction, or undergo any increase or diminution of velocity. The introduction of a second body, attracting the first and attracted by it, alters the result in a way which now demands brief consideration. If the motion with which the two bodies start is such as would carry them along a straight line toward each other, they must obviously rush together, and the case is thus again re- duced to that of a single moving body. But this case is too simple to have been ever actually realized. What we have to deal with is the 163 COSMIC PHILOSOPHY case of two bodies which are moving in inde- pendent directions. For the sake of simplicity, let us suppose that the second body, b, is so much heavier than the first body, a, that the common centre of gravity of the two lies within b's periphery. What now will be the result ? The direction of a's motion, instead of remain- ing unaltered, will be at each instant deflected from a straight line in such a way that a will continually approach nearer and nearer to a point somewhere in advance of b, upon the line in which b is moving : instead of a straight line we shall have a curve of which the coordinates will bear to each other a ratio equal to the ratio between a's momentum and b's tractive force. The velocity of a will also cease to be uniform. For as soon as a has passed on beyond b, a portion of its momentum will be at each instant consumed in neutralizing b's tractive force, so that the velocity due to the remaining momen- tum will be at each instant diminished. Now, unless a's momentum be infinite, this process cannot go on forever. By the time that a has arrived at the point directly in advance of b, so much momentum will have been lost that b's attraction will begin to overbalance it, and the curve in which a is moving will begin to turn back toward b. But now b's tractive force be- gins to augment at each instant the velocity of a, until, by the time that a has reached a 164 RHYTHM position alongside of b, its momentum is con- siderably in excess of b's attraction, and it is consequently carried on toward a point in the rear of b. The same rhythmical decrease and increase in a's momentum continues until the curve is completed, and a has reached the posi- tion from which it started. Thus our attracted body, instead of moving in a straight line, moves in a closed curve of which one of the foci must coincide in position with the common centre of gravity of the attracted and attracting bodies. The result which we have here ob- tained by supposing a to be so much smaller than b that its reciprocal influence upon b's motion might be left unconsidered is not al- tered if we suppose a and b to be equal in size. In this case the common centre of gravity lies midway between the two bodies, and is the common focus of the two closed curves respec- tively described by them. The illustration is a very trite one, being ap- proximately realized in every case of planetary revolution, but the space here given to it is jus- tified by the supreme importance of the princi- ple now to be generalized from it. To Galileo's first law of motion there is now to be added a supplemental law. As a single moving body, in an otherwise empty universe, would move for- ever with unvarying velocity in an unvarying direction ; so, on the other hand, two or more 165 COSMIC PHILOSOPHY bodies, moving in independent directions and exerting attractive forces upon each other, must forever move in directions which rhythmically vary, and with velocities which are rhythmically augmented and diminished. Thus the rhythm of motion is a corollary from the persistence of force. Our only alternatives are rhythm, or in- variable velocity in an invariable direction. The latter alternative being excluded by the fact that in the known universe innumerable bodies co- exist, it follows that we must adopt the former, and admit that all motion is and must be rhyth- mical. The direct dependence of this conclusion upon the axiom of the persistence of force is still further illustrated by the case of the pendu- lum. Let us imagine, for the sake of definite- ness, a heavy bob at the end of a rigid wire. When the bob is raised to leftward of the per- pendicular, and then left to the action of gravity, it at once begins to descend. But while it is de- scending, gravity is at each instant adding to its momentum, so that, when it reaches the per- pendicular, it cannot stop, but is carried along to rightward until all the added momentum is lost again ; that is, until it has ascended to a height equal to that from which it began to de- scend. Being now left to the unhindered action of gravity, the same series of motions will oc- cur in the reverse direction, and so on forever. 1 66 RHYTHM Strictly speaking, no such case can be realized ; since all the lost momentum is not expended in neutralizing gravity, but part of it is employed in communicating motion to the environing atmosphere, and part of it is transformed into heat. But if all the molar momentum thus dis- sipated could be retained, the rhythmic motion of the pendulum would continue forever. But why ? Simply because the momentum acquired during the descending rhythm cannot cease to manifest itself, save as it is neutralized during the ascending rhythm. And to adduce this rea- son is to appeal directly to the persistence of force. The case of undulatory motions propagated among the molecules of matter is precisely similar. The passage of an undulation implies at each instant a momentary local rarefaction, followed by a momentary local condensation. At a given instant certain molecules are removed farther from each other, while at the next suc- ceeding instant they approach each other, and the molecules immediately adjacent are removed from each other. Why is rarefaction thus suc- ceeded by condensation ? What is it that deter- mines the rebound of the disturbed molecule towards its original position ? Obviously the progress of a pair of molecules toward positions farther and farther from each other is opposed by the inertia of adjacent molecules, which these 167 COSMIC PHILOSOPHY push before them as they advance. The local rarefaction is achieved only at the expense of an adjacent condensation. This condensation of the adjacent molecules increases their elasticity until it begins to overbalance the momentum of the separating pair of molecules, and then these molecules are driven back toward each other. And so on, without intermission. Now the recoil of the advancing molecule is necessi- tated by the fact that the elasticity which it gen- erates in the resisting molecule cannot expend itself without producing motion. And to say this is to recur again to our fundamental axiom. Thus in all cases, whether molar or molecu- lar, the rhythm of motion is necessitated by the fact that in a multiform universe no portion of matter can move uninfluenced by some other portion. The illustrations just given do but typify that which is forever going on through- out the length and breadth of the Cosmos. Periodicity, rise and fall, recurrence of maxima and minima, — this is the law of all motions whatever, whether exemplified by the star rush- ing through space, by the leaf that quivers in the breeze, by the stream of blood that courses through the arteries, or by the atom of oxygen that oscillates in harmony with its companion atoms of hydrogen in the raindrop. Always, as in our initial illustration, the forces which are carrying a given portion of matter in a given 168 RHYTHM direction become gradually altered in their dis- tribution, and in their amounts, until the direc- tion of the motion becomes practically reversed ; and whether the given portion of matter be a planet or a molecule, the dynamic principle re- mains the same. Just as Newton's law of in- verse squares applies to molecules as well as to masses, so the law of rhythm applies in both cases. Thus what we may call the elementary motions going on throughout the world of phe- nomena— the elementary motions by the vari- ous combinations of which all perceptible mo- tions are made up — are all rhythmical or os- cillatory. The phenomena which are presented to our consciousness as light, heat, electricity, and magnetism, are the products of a perpetual trembling, or swaying to and fro of the invisible atoms of which visible bodies are composed. When we contemplate the heavens on a clear autumn evening, and marvel at the beauty of Sirius, that beauty is conveyed to our senses through the medium of atomic shivers, kept up during the past twenty-two years, at the average rate of six hundred millions of millions per sec- ond. The difference between the tropical heat of India and the cold of the Arctic regions is simply the measure of untold millions of tiny differences in the rates of oscillation of count- less atoms of atmospheric gases, determined in turn by innumerable oscillatory movements 169 COSMIC PHILOSOPHY propagated from the sun to the earth. The dif- ference between the faradaic current which cures some deep-seated abnormity of nutrition, and the lightning-flash which paralyzes and kills, is at bottom a difference in amounts and rates of atomic vibration. And according to the latest speculations in chemical philosophy, it is be- cause of the synchronousness or rhythmical har- mony of the oscillatory movements described by their atoms, that elementary substances are enabled to combine in myriadfold ways, thus making up the wondrous variety of forms, or- ganic and inorganic, which the earth's surface presents for our contemplation. Since the ultimate particles of which science regards the universe as composed are thus per- petually swaying to and fro, in accordance with a law of motion that admits of no exception, we may expect to find that the various aggregates of these particles which constitute perceptible bodies will exhibit a like rhythm, whether com- paratively simple or endlessly compounded, in their motions. The law which governs the ac- tion of the parts must govern also the action of the whole, no matter how intricately the whole may be compounded. Whether it be in the case of organic or inorganic bodies, of complex or of simple aggregates, we must expect to come upon systems of rhythmical movements, which will be comparatively simple or endlessly complex, 170 RHYTHxM according to the structural complication of the bodies in question. Let us exhibit a few in- stances of this rhythmical action, before we pass to the stupendous consequences of the theorem which I have been endeavouring to elucidate. Some of the chief instances to be gathered from astronomic phenomena have been so admira- bly presented by Mr. Spencer, that I cannot do better than to quote in full his concise state- ment. Along with the planetary revolutions which furnish the illustration with which I began this chapter, " the solar system presents us with va- rious rhythms of a less manifest and more com- plex kind. In each planet and satellite there is the revolution of the nodes — a slow change in the position of the orbit-plane, which after com- pleting itself commences afresh. There is the gradual alteration in the length of the axis major of the orbit, and also of its eccentricity, both of which are rhythmical alike in the sense that they alternate between maxima and minima, and in the sense that the progress from one ex- treme to the other is not uniform, but is made with fluctuating velocity. Then, too, there is the revolution of the line of apsides, which in course of time moves round the heavens — not regularly, but through complex oscillations. And further we have variations in the directions of the planetary axes — that known as nutation, 171 COSMIC PHILOSOPHY and that larger gyration which, in the case of the earth, causes the precession of the equi- noxes. " These rhythms, already more or less com- pound, are compounded with each other. Such an instance as the secular acceleration and re- tardation of the moon, consequent on the vary- ing eccentricity of the earth's orbit, is one of the simplest. Another, having more important consequences, results from the changing direc- tion of the axes of rotation in planets whose orbits are decidedly eccentric. Every planet, during a certain long period, presents more of its northern than of its southern hemisphere to the sun at the time of its nearest approach to him ; and then again, during a like period, pre- sents more of its southern hemisphere than of its northern — a recurring coincidence which, though causing in some planets no sensible al- terations of climate, involves in the case of the earth an epoch of 21,000 years, during which each hemisphere goes through a cycle of tem- perate seasons, and seasons that are extreme in their heat and cold. Nor is this all. There is even a variation of this variation. For the summers and winters of the whole earth be- come more or less strongly contrasted, as the eccentricity of its orbit increases and decreases. Hence during increase of the eccentricity, the epochs of moderately contrasted seasons and 172 RHYTHM epochs of strongly contrasted seasons, through which alternately each hemisphere passes, must grow more and more different in the degrees of their contrast ; and contrariwise during de- crease of the eccentricity. So that in the quan- tity of light and heat which any portion of the earth receives from the sun, there goes on a quadruple rhythm : that of day and night ; that of summer and winter ; that due to the chang- ing position of the axis at perihelion and aphe- lion, taking 21,000 years to complete ; and that involved by the variation of the orbit's eccen- tricity, gone through in millions of years."1 The astronomic rhythms here enumerated are peculiarly interesting from the fact that, owing to their comparatively simple character, they are susceptible of mathematical treatment, so that their direct dependence on the principle of the persistence of force can be quantitatively demonstrated. In ascending to the order of phenomena next above them in point of com- plexity — the geologic phenomena occurring on the earth's surface — we enter a region where such quantitative proof, save of a very crude sort, cannot be obtained. The great complex- ity of geologic as contrasted with astronomic rhythms is shown by the fact that whereas on the one hand we can readily calculate the vari- ations of eccentricity in the earth's orbit which 1 First Principles, pp. 256, 257. 173 COSMIC PHILOSOPHY have taken place during millions of years gone by or which are sure to take place during mil- lions of years to come, on the other hand we are not yet able to assign an approximate date for the most recent epoch at which our north- ern hemisphere was covered with glaciers. Ac- cording to Mr. Wallace this epoch may have occurred no more than seventy thousand years ago, while others would assign to it an antiquity of at least two hundred thousand years, and there are yet others who urge strong arguments in behalf of the opinion that a million of years is barely enough to have produced the changes which have taken place since that event. Nev- ertheless, though we cannot determine the amounts and durations of the movements which have occurred during the geologic history of the earth, we can still securely assert that these movements have been rhythmical in character. Though the verdict is rendered with less pre- cision, its purport is still the same. In the alternating periods of elevation and depression which have succeeded each other at different places ever since the earth's crust began to be solidified, are exemplified the chief geologic rhythms, due to the slow deflection of the lines of least resistance along which the pressure of the earth's nucleus reveals itself by causing upward motion. But these immensely long rhythms are complicated by minor rhythmical 174 RHYTHM changes of surface, due to continual shifting of river-beds and consequent variations in the areas of denudation and in the deposit of sedimentary- strata. And these rhythms are still further com- plicated by rhythmic variations in the operation of climatic agencies, entailing periodic changes in the amount and distribution of rainfall, in the size and movements of icebergs and glaciers, and in the activity of frost. On the seashore we may witness the compound rhythm of the tides, in " which the daily rise and fall undergo a fortnightly increase and decrease, due to the alternating coincidence and antagonism of the solar and lunar attractions; " a source from which arise the most minute geologic rhythms, as those which arise from the secular cooling of the earth, and from its ever varying position in space, are the most vast. But the subject of complex rhythms is still better illustrated in biology. The commonest physiological act, such as eating, is dependent upon a periodically occurring sensation of hun- ger, due to a periodic excess of waste over re- pair. The taking of nutriment is accomplished, in all animals, by a series of rhythmical motions, — either the motions of cilia, or of sphincter muscles, or of jaws, or indeed of all three at once. Mr. Spencer adds that " the swallowing of food is effected by a wave of constriction passing along the oesophagus ; its digestion is *75 COSMIC PHILOSOPHY accompanied by a muscular action of the stom- ach that is also undulatory ; and the peristaltic motion of the intestines is of like nature. The blood obtained from this food is propelled not in a uniform current but in pulses ; and it is aerated by lungs that alternately contract and expand." To this we may add that assimilation is a continuous process of rhythmic interchange between the molecular constituents of the vari- ous tissues and of the blood by which they are bathed ; that muscular action is the result of a series of oscillatory movements ; and that ner- vous action depends upon a quickly alternating rise and fall in the chemical instability of the molecules which compose the nerve-centres. All these minor rhythms are as ripples upon the surface of the longer rhythm constituted by sleep and wakefulness. Recent researches have shown that sleep itself furnishes a beautiful illus- tration of the manner in which rhythm is neces- sitated by the continual redistribution of forces in the organism. According to the most recent view, sleep is caused by a diminution in the ca- pacity of the cerebral arteries, which lessens the circulation of blood through the brain. It is the sympathetic nerve which effects this contraction of the arteries. During the day the activity of the cerebrum itself supplies the stimulus which causes arterial blood to flow through the head in large quantities, so as to keep the vessels 176 RHYTHM duly distended. But after many hours of activ- ity the ratio of repair to waste is sensibly di- minished ; there is a fall in the average chemical instability of the cerebral nerve-molecules, and a consequent diminution in the amount of cere- bral stimulus ; until presently the amount of stimulus sent up from moment to moment along the cervical branch of the sympathetic nerve exceeds the amount which the cerebrum can oppose to it. Experiment has shown that the effect of stimulating the sympathetic nerve is to contract the muscular walls of the cerebral arteries. The supply of arterial blood is thus so far diminished that consciousness ceases. But now the other half of the rhythm begins. The cessation of conscious activity greatly di- minishes the waste of cerebral tissue — and, although repair is also somewhat lessened by the lessened blood-supply, yet the ratio of repair to waste is increased. The complex nerve- molecules are built up to higher and higher grades of instability, until it only needs a slight stimulus from without, in the shape of a sensa- tion of sound or of light or of touch, to elicit a discharge of nerve-force from the cerebral gan- glia. This discharge is instantly answered by a rush of blood, which distends the cerebral arte- ries, revives consciousness, and holds in abey- ance the contractile energy of the sympathetic nerve, until the decreasing ratio of repair to VOL. II 177 COSMIC PHILOSOPHY waste by and by necessitates a recurrence of the rhythm. Thus the alternation of sleep and wakefulness is due to a periodic variation in the ratio between the amount of nerve-force stored up in the cerebrum and the amount stored up in the sympathetic ganglia. We recognize this truth in practice when we seek to induce sleep by stimulating the sympathetic nerve with such substances as bromide of po- tassium. The phenomenon of sleep is still further in- teresting as the most familiar instance of the de- pendence of biologic rhythms upon astronomic rhythms. All organisms, animal and vegetable, from the highest to the lowest, exhibit alterna- tions in the total distributions of their forces, which coincide with the periodic appearance and disappearance of sunlight. The longer astrono- mic rhythm, known as the earth's annual revo- lution, causes corresponding rhythms in vege- table and animal life ; witness the blossoming and leafing of plants in the spring, the revival of insect activity at the same season, the peri- odic flights of migratory birds, the hibernating sleep of many vertebrates, and the thickened coats or the altered habits of others that do not hibernate. If we consider the species instead of the individual, we shall find that still longer astronomic rhythms, often complicated by geo- logic rhythms, cause periodic changes in the 178 RHYTHM total manifestations of life upon the earth's sur- face. Recurring epochs of high eccentricity of the earth's orbit have so altered the distribution of solar radiance as to cause violent climatic vicissitudes. Large portions of the earth have been covered by glaciers, and there have been ensuing migrations of plants and animals, at- tended by the extinction of many forms, and by specific variations among the survivors. Other rhythms in the distribution of life have been caused by alternations in the elevation and sub- sidence of continents and islands. And all the foregoing causes, taken altogether, have been endlessly complicated by rhythmic changes in the relations of various groups of organisms to one another. The complexity of such relations is strikingly illustrated in an instance given by Mr. Darwin. The fertilization of heartsease and red clover is impossible without the agency of humble-bees in carrying the pollen from one flower to another. Other bees do not visit these flowers, as their probosces are not long enough to reach the nectar ; while moths, which have sufficiently long probosces, are not heavy enough to bend down the petals in such a way that the anthers above may shed pollen upon their backs. Hence the partial or total destruction of humble- bees must involve the decrease or extinction of heartsease and red clover. But observation shows that the mortal foes of humble-bees are 179 COSMIC PHILOSOPHY field-mice, who destroy their combs and nests. It is estimated that in England more than two thirds of each generation of humble-bees are destroyed by mice. Hence it follows that the cat is a friend and protector of the humble-bee ; and that any sensible variation in the number of cats in a given district must indirectly cause a variation in the numbers of heartsease and red clover which grow in the neighbourhood. It is only needful to add that in such variations we have a series of endlessly complex rhythms ; as is obvious from the fact that the number of in- dividuals in any species is never constant, but is continually fluctuating about an average mean. The cumulative result of such rhythms, going on through countless ages, is witnessed in the rhythmical changes of organic species revealed by palaeontology. In all ages species have been encroaching on each other, and while some have been growing more abundant, others have gradu- ally disappeared. Thus we find successive floras and faunas, characteristic of successive geologi- cal epochs, showing that " life on the earth has not progressed uniformly, but in immense un- dulations." For the further illustration and more abun- dant proof of the law that all motion is rhythmi- cal, I must refer to Mr. Spencer's " First Prin- ciples," where the subject is discussed much more fully than is here practicable. But our 1 80 RHYTHM last illustration, from the succession of forms of life upon the earth, suggests still another su- premely important aspect in which the general principle must be viewed, before we leave it. As we saw in our initial illustration, from the movements of heavenly bodies, where a rhyth- mical motion is dependent on only two com- pounded forces, the result is a closed curve. Though each planet is, strictly speaking, sub- jected to a great number of variously com- pounded forces exerted on it by all its compan- ion planets, yet these forces are so insignificant in quantity, compared to the two chief forces of solar gravity and the planet's own momen- tum, that they do not essentially alter the re- sult. They prevent the curve in which any given planet moves from being perfectly regular, but they do not prevent its being a closed curve so far as the solar system alone is concerned ; so that, at the end of each rhythm, the distri- bution of forces is very nearly the same as at its beginning. If there were only two bodies concerned, it would be exactly the same : every rhythm would end in bringing about precisely the same state of things with which it started. But where there are a vast number of forces at work, as in the evolution of the earth and of life upon its surface, the probability is infinitely small that any pair of forces can so far predomi- nate over all the rest as to reduce their effects 181 COSMIC PHILOSOPHY to comparative insignificance. Hence the re- sulting rhythms will not be closed curves, but endlessly complicated undulations ; and every rhythm will end in bringing about a state of things somewhat different from that in which it started. To recur to some of the illustrations above given : No geologic rhythm of eleva- tion and subsidence leaves the distribution of land and water over the earth exactly as it found it. No biologic rhythm of sleep and wakeful- ness leaves the distribution of nutritive forces in the organism precisely as it found it ; other- wise it would not be true that each day's func- tional activity is a member of the series of changes which is bearing us from the cradle to the grave. In an exogenous tree each an- nual rhythm results in a permanent increase of woody fibre : in a mammal it results in at least a relative increase of the solid constituents of the body as compared with the fluid and semi- fluid constituents. And our illustration from palaeontology shows that the series of enormous rhythms in which the history of organic life consists, has introduced a new state of things in each geologic epoch.1 We have now proceeded as far as a survey 1 Hence the theory of Vico, that social progress takes place in cycles in which history literally repeats itself", is based upon a very inadequate knowledge of the results of the cooperation of many interacting forces. 182 RHYTHM of the widest generalizations of physics can carry us, and before we attempt to go further, we may fitly present in a single view the con- clusions reached in this and in the preceding chapter. We observed first that the three departments of abstract-concrete science are alike concerned with the investigation of the general laws of force as manifested in the motions of matter. By an analysis of the widest propositions which these sciences can furnish, concerning the move- ments of masses and molecules, we arrived at the axiom that every manifestation of force must be preceded and followed by an equiva- lent manifestation. We saw that this axiom is involved, alike in every special theorem with which each physical inquiry sets out, and in the general theorem of the uniformitv of law and the universality of causation with which all phy- sical inquiries must equally set out. We saw next that this axiom gives rise to three corolla- ries which, as expressing truths that transcend the sphere of any single science, belong to that transcendental region of knowledge which we have assigned to philosophy. By our first cor- ollary it appeared that any given mode of mo- tion may be metamorphosed into several other modes ; so that, when we contemplate such a complex system of motions as that presented by the various aggregations of matter upon the 183 COSMIC PHILOSOPHY surface of our earth, it becomes legitimate to inquire from what antecedent form of energy proceeded all these motions. This inquiry we shall make in due season. By our second cor- ollary it appeared that where motion results from the composition of two or more forces, it must always take place in the line of least re- sistance ; but that the difficulty of calculating or predicting this resultant line must increase very rapidly with each addition to the number of forces which are concerned in producing it. Our third corollary has given us glimpses of a truth, which, though less immediately obvious, is equally necessary and equally important with any of the foregoing. We have seen that, in the hypothetical case of a single moving body in an otherwise empty universe, the direction of motion would be in a straight line, and the velocity would be uniform. In the hypotheti- cal case of a single pair of mutually attracting bodies moving in independent directions in an otherwise - empty universe, the motion would be rhythmical both in direction and in velocity, but it would take place in closed curves, and the distribution of forces at the end of each rhythm would be the same as at the beginning. In the simplest of actual cases, however, — in the case of our planetary system, — such a re- sult, though apparently realized so long as we eliminate from the problem all factors save the 184 RHYTHM two principal ones, is not truly realized ; and if we were to take into account the motions of the whole system, due to the forces exerted upon it by remote stellar systems, we should see that it is very far from being realized. Viewed in its relations to the entire visible universe of stellar bodies, no planet moves in a closed curve; and if we also take into consideration the un- ceasing loss of molecular motion by each cos- mical body, we shall perceive that even in this relatively simple class of cases, the rhythms are far too complex ever to result in the reproduc- tion of a given distribution of forces. In the relatively complex cases furnished by geology and biology, this truth is still more strikingly exemplified. Thus in the actual case with which our science has to deal — the case of a universe in which innumerable millions of bodies, from a gigantic star like Sirius down to an inconceiv- ably minute atom of hydrogen, are ceaselessly exerting forces upon each other — we see, not only that all motions must be rhythmical, but that every rhythm, great or small, must end in some redistribution, be it general or local, of matter and motion. Or to state this final conclusion in a slightly different form, — the mere coexistence of a vast number of bodies in the universe necessi- tates perpetual rhythm, resulting in a contin- uous redistribution of matter and motion. Thus 185 COSMIC PHILOSOPHY fresh significance is given to the truth vaguely- surmised by Herakleitos, that ceaseless change is the law of all things, and that the universe of phenomena is in a never-ending flux. But the scientific demonstration further shows us that the change is always from an old state to a new state, and thence to another new state, but never back to the old state. Among the untold millions of forces which science contem- plates as cooperating to bring about any given state of things, the permutations and combina- tions are practically infinite ; and not until they have all been exhausted can an expired epoch be reproduced in all its features. 186 CHAPTER III EVOLUTION AND DISSOLUTION WE must now consider what use is to be made of these universal truths which the foregoing survey of the abstract-concrete sciences has disclosed. For if we inquire whether these theorems, singly or combined, can be made to supply the materials needful for constructing such an organized body of truths as may fitly be called Cosmic Philoso- phy, it will require but a brief consideration to show us that much more is needed. In respect of universality, no doubt, these truths leave nothing to be desired. That every manifestation of force must be preceded and followed by an equivalent manifestation ; that correlated forms of energy are transmutable one into the other ; that motion follows the line of least resistance ; and that there is a continuous rhythmical redistribution of matter and motion ; — these are propositions which are true alike of all orders of phenomena, and may therefore justly claim to be regarded, in a certain sense, as philosophic truths. Yet we need only fancy ourselves enunciating these abstract theorems 187 COSMIC PHILOSOPHY as of themselves supplying the explanation of any given order of concrete phenomena, in or- der to realize how far we still remain from our desired goal. If we were to remind a biologist that in every step of his investigations he takes for granted the persistence of force, he would doubtless assent ; but if we were to go on and assert that upon this axiom might be directly reared a science of organic phenomena, he would laugh us to scorn. If we were to assure him that every form of energy manifested by his organisms, from the molar motions of the stom- ach in digestion and the lungs in respiration to the molecular motions of cerebral ganglia, must have preexisted in some other form, he would thoroughly agree with us, but would ask us of what use is all this unless we can trace the course and the results of the transformations. If we were still to insist that all the motions taking place in the aforesaid organisms occur rhyth- mically, along lines of least resistance, and that every such rhythm ends in a more or less con- siderable redistribution of molecular motions, we might still be met by the answer that all this does not give us a science of biology unless we can also point out the general character and di- rection of the changes in which organic rhythms result. In other words, our biologist might say to us, with Mr. Spencer, that all these profound 1 88 EVOLUTION AND DISSOLUTION truths, with which we were seeking to take away his occupation, are analytical truths, and that " no number of analytical truths will make up that synthesis of thought which alone can be an interpretation of the synthesis of things. The decomposition of phenomena into their elements " (he would continue) " is but a pre- paration for understanding phenomena in their state of composition, as actually manifested. To have ascertained the laws of the factors is not at all to have ascertained the laws of their cooperation. The question is, not how any factor behaves by itself, or under some imagined simple conditions ; nor is it even how one factor behaves under the complicated conditions of actual existence. The thing to be expressed is the joint product of the factors under all its vari- ous aspects. Only when we can formulate the total process, have we gained that knowledge of it which Philosophy aspires to."1 It is necessary for us therefore, having fin- ished our analysis, to begin the work of syn- thesis. In the course of our search for the widest generalizations of Physics, we discovered, as the most concrete result of analysis, that there is going on throughout the known universe a continuous redistribution of matter and motion. Let us now, following out the hint of our im- aginary interlocutor, endeavour to ascertain the 1 First Principles, p. 274. 189 COSMIC PHILOSOPHY extent, character, and direction of this contin- uous redistribution. Have the infinitude of changes in the aspect of things, which the rhythm of motion necessitates, any common character, and if they have, what is that charac- ter ? Are the redistributions of matter and mo- tion, which are going on all around us, aimless and unrelated, or do they tend in common toward some definable result ? Can any for- mula be found which will express some dynamic principle, true of the whole endless metamor- phosis ? Or, to state the case in a still more concrete form, when we assert " that knowledge is lim- ited to the phenomenal, we have by implication asserted that the sphere of knowledge is coex- tensive with the phenomenal. Hence wherever we now find Being so conditioned as to act on our senses, there arise the questions — how came it thus conditioned? and how will it cease to be thus conditioned ? Unless on the assump- tion that it acquired a sensible form at the mo- Slment of perception, and lost its sensible form Jie moment after perception, it must have had "U antecedent existence under this sensible a!\m, and will have a subsequent existence i<>r this sensible form. These preceding and uncV*eding existences under sensible forms are succV>le subjects of knowledge ; and knowledge PosslWiously not reached its limits until it has has or I90 EVOLUTION AND DISSOLUTION united the past, present, and future histories into a whole." ' Let us not fail to note that science and ordi- nary knowledge concern themselves with such problems no less than philosophy ; and that in seeking to formulate the past, present, and fu- ture history of that aggregate of sensible pheno- mena which constitutes the knowable universe, philosophy transcends the sphere of science in just the same way that science transcends the sphere of ordinary knowledge, and in no other. A large portion of that imperfectly organized knowledge that serves to guide the actions even of the least educated men, consists of information concerning the past and future careers of the ob- jects which surround them. Thus we recognize the child of twenty years ago in the grown man of to-day ; we know that the coat which the man wears recently existed in the shape of unspun and unwoven wool upon a sheep's back ; and that the grass upon which this sheep fed con- sisted of matter integrated by countless seeds with the aid of solar radiance. And we know, besides, that the man and the coat which he wears, the sheep and the grass upon which it feeds, must alike pass from their present state of aggregation into a future state of dissolution^ This kind of knowledge science is ever extend- ing, as when it traces back the man and the i First Principles, p. 278, 191 COSMIC PHILOSOPHY sheep to microscopic germ-cells, and the wool and the grass to certain nitrogenous and hydro- carbon compounds, preexisting in the atmo- sphere and soil. Obviously, therefore, it is the business of philosophy, extending and general- izing the same kind of information, to describe the universal features of the process by which cognizable objects acquire and lose the sensible forms under which we know them. By pointing out the two most obvious fea- tures of this process, we shall render still more intelligible the character of the problem which a synthetic philosophy must attempt to solve. The foregoing illustrations show us that a com- plete account of anything " must include its appearance out of the imperceptible, and its disappearance into the imperceptible." Now a change of state by virtue of which any object ceases to be imperceptible and becomes percep- tible must be a change from a state of diffusion to a state of aggregation, — and the converse change, from aggregation to diffusion, must be the change by virtue of which the object again becomes imperceptible. If, for example, we study a cloud, we find that a complete history of it is contained in the explanation of its concen- tration from millions of particles of aqueous vapour, and its subsequent dissipation into a host of such particles. In like manner, if we study an organism, we find that from germi- 192 EVOLUTION AND DISSOLUTION nation to final decomposition, its career consists of an epoch of concentration followed by an epoch of diffusion. A very small portion of its constituent matter preexisted in a concentrated form in the embryo ; by far the greater portion preexisted in the shape of dispersed nitroge- nous and carbonaceous compounds, which the growing organism has incorporated with its own structure. Nay, even if we inquire into the previous history of the small portion which was concentrated in the embryo, we may trace it back to an epoch at which it existed in a state of dispersion, as food not yet assimilated by the parent organism. If the organism in question belong to an order of carnivorous animals, we shall indeed have to follow its constituent ele- ments through a series of phases of concentra- tion ; through the tissues of sundry herbivo- rous animals upon which it has fed, and again through the tissues of numerous plants upon which these have in turn subsisted ; but in the end we shall always arrive at the host of dis- persed molecules which these organisms have eliminated from the breezes and the trickling streamlets by which their leaves and roots were formerly bathed. On the other hand, when the animal dies, and the tree falls to decay, the par- ticles of which they consist are again dispersed ; and though they may again be brought together in new combinations, the career of the organism vol. n. I 93 COSMIC PHILOSOPHY in question is ended with this dispersal. Again if, instead of a transient cloud or a mobile or- ganism, we contemplate an apparently perma- nent and immobile rock, we are led to a like conclusion. If its origin be purely igneous, this rock may have preexisted as a liquid stream of matter surging beneath the earth's solid enve- lope. If its origin be aqueous, its constituent particles were once diffused over a wide area of country, from which they were drawn together through sundry rivulets and rivers, and here at last deposited as sediment. In either case the process by which the rock has assumed an individual existence has been a process of concentration. And when it ceases to exist — whether it is blasted with gunpowder, or chipped away with chisels, or eaten down by running water, or ground to pieces by ocean waves, or lowered through some long geologic epoch till it is melted by volcanic heat — in any case its disappearance is effected by a process of diffu- sion. But our account is as yet only half complete. In saying that the career of any object, from its initial appearance to its final disappearance, con- sists of a process of concentration followed by a process of diffusion, we omit an important half of the truth. For in making such a statement, we are attending only to the material elements of which objects are composed ; and we are leav- 194 EVOLUTION AND DISSOLUTION ing out of the account the motions, both molar and molecular, which they exhibit, and which constitute an equally important part of the en- tire process. This defect we must now endeav- our to remedy. A brief reconsideration of the examples al- ready cited will show us that universally the con- centration of matter is accompanied by a dissi- pation of motion, while conversely the diffusion of matter is attended by an absorption of mo- tion. The condensation of aqueous vapour into a cloud is effected whenever it loses by radiation a greater quantity of that kind of molecular mo- tion known as heat than it is receiving from the sun and the earth ; and when the loss of motion is still more considerable, there occurs a further condensation of the aqueous vapour into liquid rain. Conversely, when solar radiance, direct or reflected, begins to impart to the condensing cloud an amount of molecular motion in excess of that which it loses from moment to moment, condensation ceases, and the particles of vapour begin to be dissipated. The deposit of sediment at the mouth of a river is attended by the loss of the molar motions which brought its constitu- ent particles from the upland regions which the river drains ; and the hardening of the sediment into rock is a change to a state of aggregation in which, along with greater cohesion, the par- ticles possess less mobility than before. In like J95 COSMIC PHILOSOPHY manner the hardening of an igneous rock is effected by cooling, which implies the loss of internal motion. Indeed the phenomena of heat and cold exhibit en masse an illustration of the general principle. The progress of any mass of matter from a gaseous to a liquid, and thence to a solid state, is attended by the continuous dis- sipation of molecular motion ; while change in the contrary direction is attended by a contin- uous absorption of such motion. With molar motions the case is precisely similar. " Aug- ment the velocities of the planets, and their or- bits will enlarge ; the solar system will occupy a wider space. Diminish their velocities, and their orbits will lessen ; the solar system will contract. And in like manner we see that every sensible motion on the earth's surface involves a partial disintegration of the moving body from the earth, while the loss of its motion is ac- companied by the body's reintegration with the earth." Finally, if we consider the case of or- ganisms, we find that the incorporation of food into the substance of the tissues is constantly accompanied by the giving out of motion in some form of organic activity, while conversely, the decomposition which follows death is at- tended by an immense absorption of molecular motion. The latter statement is proved by the fact that the elements of which such an organism as the human body is composed have more than 196 EVOLUTION AND DISSOLUTION twenty times the volume when free which they have when combined ; and it is further illus- trated by the fact that dead organisms, from which all supply of molecular motion from with- out is artificially cut off, are not decomposed. It is thus that animal remains are preserved for ages in blown sand and in peat-moss. And it is thus that the carcases of primeval mammoths, intact even to the bulbs of the eyes, are found embedded in arctic ice near the mouths of Si- berian rivers, just where they were slain by the cold a thousand centuries ago.1 But the study of organic phenomena shows us that our general theorem needs some further re- vision. As it now stands, it runs some risk of being supposed to assert that the career of any composite body is at first characterized solely by the concentration of matter and concomitant dissipation of motion, and is at last character- ized solely by the diffusion of matter and con- comitant absorption of motion. A reference to the history of any organism will at once show that this is not the case. While the human body, for example, is continually incorporating with its tissues new matter in the shape of pre- pared food, large portions of the matter once incorporated are continually diffused in the 1 The heads of these animals are nearly always directed southward. See Lyell, Principles of Geology, ioth edition, vol. i. p. 184. 197 COSMIC PHILOSOPHY shape of excretions through the lungs, liver, skin, and kidneys. And while it is constantly- parting with motion, in the shape of radiated heat, of expended nerve-force, and of molar mo- tion communicated to the surrounding objects which it touches or handles, it is at the same time absorbing large quantities of molecular motion latent in its prepared nutriment. But at no time are the antagonist processes exactly balanced. During early life the excess of con- centration over diffusion of matter results in growth. At a later date the rhythms due to the alternate predominance of concentration and diffusion are exhibited in continual fluctuations in weight. Yet the fact that the healthy body usually increases in weight up to a late period shows that ordinarily concentration is still pre- dominant. And this is still more convincingly proved by the fact that in old age, when the body frequently decreases both in weight and in volume, the weight decreases less than the vol- ume. There is a general increase in density, and concomitant loss of mobility, due to the in- creased ratio of the solid to the fluid constitu- ents of the tissues, and exhibited in the hard- ness and brittleness of the bones, the stiffness of the joints, the sluggishness of the circulation, and the torpidity of the brain. Finally when, in accordance with the general principle of rhythm, the consolidation has gone so far as 198 EVOLUTION AND DISSOLUTION to become self-defeating, the antagonist process gains the mastery for which it has all along been striving, and the constituents of the body are separated and scattered. But the coexistence and alternate mastery of these two opposing processes, though most strikingly exemplified in the case of organisms, is by no means confined to organic phenomena. Neither in the cloud, nor in the rock, which we have chosen as examples, does concentration or diffusion ever go on alone. The one is always antagonized by the other. Even while the cloud is most rapidly losing motion and integrating matter, it is receiving some solar radiance, either direct or reflected from the earth or moon, and the absorption of this radiance causes some dis- integration of its matter. Even while it is most quickly vanishing under the burning solar ravs, this cloud is still simultaneously losing heat by radiation, and the loss tends to reintegrate it. And likewise our sedimentary rocky deposit, while aggregating, is nevertheless daily abraded by passing currents, and at longer intervals is perhaps cracked by those telluric vibrations known as earthquakes. As finally amended then, our formula asserts that the career of any composite body is a se- ries of more or less complicated rhythms, of which the differential result is, at first, the in- tegration of its constituent matter and the dis- 199 COSMIC PHILOSOPHY sipation of part of its contained motion, and, at last, the diffusion of its constituent matter ac- companied by reabsorption of the lost motion, or its equivalent. Thus we are gradually reaching something like a concrete result. As we saw, in the pre- ceding chapter, that rhythm necessitates a con- tinual redistribution of matter and motion throughout the knowable universe, we now find that this continual redistribution every- where results in alternate concentration and diffusion. Such, indeed, must inevitably be the result. The same universal principle of dyna- mics which prevents the perturbations in the solar system from ever accumulating all in the same direction is also to be seen exemplified, on a more general scale, in the law that neither aggregation nor diffusion can proceed indefi- nitely without being checked by the counter- process. Unless we suppose that the sum of the forces which produce aggregation is infinitely greater or infinitely less than the sum of the forces which resist aggregation, so that either the one or the other may be left out of the account, we must admit that the only possible outcome of the conflict between the two is a series of alternations, both general and local, between aggregation and dissipation. It is now the time to apply to these antagonist processes some more convenient and accurate 200 EVOLUTION AND DISSOLUTION names than the half-dozen pairs of correlative synonyms by which we have thus far described them. The names selected by Mr. Spencer will be practically justified by the entire exposi- tion contained in the following chapters ; but even the cases already fragmentarily studied enable us partly to realize the significance of the terms Evolution and Dissolution, by which he has designated these processes. In Mr. Spencer's terminology, the integration of matter and concomitant dissipation of motion is Evo- lution — while the absorption of motion and concomitant disintegration of matter is Disso- lution. Both these terms possess the signal advantage that, while they admit of precise scientific definition, they are at the same time currently used in senses strictly analogous to those in which they are here employed. As we shall presently see, the phenomena of or- ganic life are those in which both the primary and the secondary characteristics of Evolution and Dissolution are most conspicuously exem- plified. Especially in the career of the ani- mal organism, these complementary processes are manifested in groups of phenomena that are more easily generalized and more immedi- ately interesting than any others of like com- plexity ; and to these groups of phenomena the terms Evolution and Dissolution have long been popularly applied. 20 1 COSMIC PHILOSOPHY On a superficial view it may now seem as if we were ready to proceed, in the next chapter, to describe in detail the process of Evolution, as exemplified in that most gigantic instance of concentration of matter and dissipation of motion, — the development of our planetary system, by condensation and radiation, from ancestral nebulous matter. In. this origin, by aggregation, of our system of worlds, and in that ultimate dissipation of it into nebulous matter which sundry astronomic facts have long taught us to anticipate, we shall presently find a complete and striking illustration of the dy- namic principles herein set forth. But we are not yet quite prepared to enter upon the con- sideration of these phenomena. We need but remember that in the development of the solar system, with its mutually dependent members sustaining complex and definite relations to each other, much more is implied besides con- centration of planetary matter and diffusion of molecular motion in the shape of heat ; we need but remember this, and we shall see that some further preliminary study is requisite. While, indeed, the primary characteristics of Evolution and Dissolution are those which are expressed in the pair of definitions above given, and which it has been the object of the foregoing inquiry to illustrate ; there are also, as just hinted, certain secondary characteristics which 202 EVOLUTION AND DISSOLUTION it is equally necessary to formulate. While Evolution always consists primarily in an inte- gration of matter and concomitant dissipation of motion, it ordinarily implies much more than this. And it is obvious that only when all the characteristics, both primary and secondary, of Evolution and Dissolution, are expressed in a single formula, can we be said to have obtained the law of the continuous redistribution of matter and motion which rhythm necessitates throughout the knowable universe. To show how this, the most sublime achieve- ment of modern science, has been brought about, will be the object of the following chapter. 203 CHAPTER IV THE LAW OF EVOLUTION LAPLACE has somewhere reminded us that, while gratefully rendering to New- •• ton the homage due to him for his transcendent achievements, we must not forget how singularly fortunate he was in this — that there was but one law of gravitation to be dis- covered. The implication that, if Newton had not lived, Laplace might himself have been the happy discoverer is perhaps a legitimate one, though it does not now especially concern us. But the implied assertion that Nature had no more hidden treasures comparable in worth and beauty to that with which she rewarded the patient sagacity of the great astronomer is one which recent events have most signally refuted. We now know that other laws remained be- hind — as yet others still remain — unrevealed ; laws of nature equalling the law of gravitation in universality, and moreover quite as coy of detection. For while it may be admitted that the demonstrations in the " Principia " required the highest power of quantitative reasoning yet manifested by the human mind ; and while the 204 THE LAW OF EVOLUTION difficulties and discouragements amid which Newton approached his task, destitute as he was alike of modern methods of measurement and of the resources of modern analysis, im- press upon us still more forcibly the wonderful character of the achievement ; it must still be claimed that the successful coordination of the myriad-fold phenomena formulated by the Law of Evolution was a gigantic task, requiring the full exertion of mental powers no less extraor- dinary than those required by the other. In an essay published thirteen years ago, youthful enthusiasm led me to speak of Mr. Spencer's labours as comparable to those of Newton both in scope and in importance. More mature re- flection has confirmed this view, and suggests a further comparison between the mental qualities of the two thinkers ; resembling each other as they do, alike in the audacity of speculation which propounds far-reaching hypotheses and in the scientific soberness which patiently veri- fies them ; while the astonishing mathematical genius peculiar to the one is paralleled by the equally unique power of psychologic analysis displayed by the other. As in grandeur of con- ception and relative thoroughness of elaboration, so also in the vastness of its consequences — in the extent of the revolution which it is destined to effect in men's modes of thinking, and in their views of the universe — Mr. Spencer's 205 COSMIC PHILOSOPHY discovery is on a par with Newton's. Indeed, by the time this treatise is concluded, we may perhaps see reasons for regarding it as, in the latter respect, the superior of the two. To give anything like an adequate idea of the extent and importance of this discovery, or of the enormous mass of inductive evidence which joins with deduction in establishing it, is of course impracticable within the limits of a single chapter. We must be content for the present with exhibiting a rude outline-sketch of its most conspicuous features, leaving it for the succeeding series of discussions to finish the picture. Let us begin by briefly summing up the results already obtained. It has been shown that the coexistence of an- tagonist forces throughout the knowable uni- verse necessitates a universal rhythm of motion; and that in proportion to the number of forces anywhere concerned in producing a given set of motions, the resulting rhythms are complex. It has been further shown that, save where the rhythms are absolutely simple — a case which is never actually realized — there must occur a redistribution of matter and motion as the result of each rhythm. It next appeared that such a redistribution involves on the one hand an inte- gration of matter, which implies a concomitant dissipation of motion, and on the other hand a disintegration of matter, which implies a con- 206 THE LAW OF EVOLUTION comitant absorption of motion. The former process, which results in the acquirement of an individual existence by sensible objects, has been named Evolution — the latter process, which results in the loss of individual existence by sensible objects, has been named Dissolu- tion. And we saw it to be a corollary from the universality of rhythm that, while these two antagonist processes must ever be going on simultaneously, there must be an alternation of epochs during which now the former and now the latter is predominant. In conclusion, it was barely hinted that these two fundamental modes of redistribution must give rise, in the majority of cases, to secondary redistributions, which it is the business of a scientific philosophy to de- fine and formulate. Now, as we are about to start upon a long and complicated inquiry, the proper treatment of which must task our utmost resources of exposition, it will be desirable at the outset to disencumber ourselves of all such luggage as we are not absolutely obliged to take along with us. We shall therefore, for the present, leave the process of Dissolution entirely out of the account, or shall refer to it only incidentally, in cases where such a reference may assist in the elucidation of the counter-process. In the following chapter we shall have occasion to treat of Dissolution in some detail as exemplified in 207 COSMIC PHILOSOPHY the probable future disintegration of our plan- etary system ; at present we are concerned only with Evolution, which we have already seen to consist in the integration of matter and concom- itant dissipation of motion, but which, as we shall presently see, implies in most cases much more than this. Let us first point out the con- ditions under which the secondary redistribu- tions attending Evolution take place ; and let us then proceed to point out the common char- acteristics of these secondary changes. Obviously in speaking of secondary redistri- butions that go on while a body is integrating its matter and losing its motion, we refer to re- distributions among the parts of the body and among the relative motions of the parts, — or, in other words, to alterations in structure and function going on within the body. Now the ease with which such redistributions are effected, and the ease with which they are maintained, must depend alike, though in precisely opposite ways, upon the amount of motion retained by the integrating body. The greater the amount of retained motion, the more easily will inter- nal redistributions be effected. The smaller the amount of retained motion, the more easily will such redistributions be rendered permanent. These propositions are so abstruse as to require some further illustration. When water is converted, by loss of its in* 208 THE LAW OF EVOLUTION ternal motion, into ice, the amount of secondary rearrangement which occurs among its particles is comparatively slight, but it is permanent so long as the state of integration lasts. During the continuance of the solid state there is not enough mobility among the particles to admit of further rearrangement to any conspicuous extent. On the other hand, after steam has been integrated into water, the retention of a consid- erable amount of molecular motion allows in- ternal rearrangement to go on so easily and rapidly that no momentary phase of it has a chance to become permanent ; and there can thus be no such stable arrangement of parts as we call structure. The phenomena of crystal- lization supply us with kindred, but slightly different examples. When a crystal is deposited from a solution, there is a certain point up to which the retention of motion keeps the crys- tal's molecules from uniting ; but as soon as this point is passed, the motion is suddenly lost, the* crystal solidifies, and there is no further redis- tribution of its particles. Conversely, when a molten metal is allowed to cool until it assumes a plastic semi-fluid state, its molecular motion is lost so slowly that a perceptible rearrange- ment of parts is possible : currents mav be set up in it, gravity will cause it to spread out wherever it is not confined at the side, and pressure here and there will variously mould it. vol. n 209 COSMIC PHILOSOPHY But when it becomes solid, the rearrangements which occurred latest become permanent, and further rearrangements cannot be produced save by a fresh supply of molecular motion. In like manner, when we come to study planetary evo- lution, we shall find strong reasons for believ- ing that on small bodies, like the moon and the asteroids, which have rapidly lost their internal heat, there has been but little chance for such complex secondary rearrangements as have oc- curred upon our relatively large and slowly cool- ing earth. Even after the attainment of solidity, how- ever, a new supply of motion from without may cause some further redistribution without caus- ing the body to relapse into fluidity. Thus a wrought-iron rail, which when new is tough and fibrous, gradually acquires the brittle crystalline texture of cast-iron, under the influence of the vibrations communicated by the cars which pass •bver it. And the magnetization of steel rods, when fastened in the meridian and frequently jarred, is cited by Mr. Spencer as a fact of like import. Many other excellent illustrations, gathered from physics and chemistry, may be found in the thirteenth chapter of the second part of " First Principles." ! If now we contemplate in a single view the 1 Throughout this work, reference is made only to the sec- ond and rewritten edition of First Principles, London, 1867. 2IO THE LAW OF EVOLUTION general principles above illustrated, we shall seem for a moment to have got into difficulties. Unavoidably, in using the word Evolution, we have suggested the idea of increase in structural complexity ; and such increase of course implies ,a considerable amount of permanent internal rearrangement as consequent upon the primary process of integration. Yet under the conditions thus far studied, we find that " on the one hand, a large amount of secondary redistribution is possible only where there is a great quantity of contained motion ; and, on the other hand, these redistributions can have permanence only where the contained motion has become small — op- posing conditions which seem to negative any large amount of permanent secondary redistri- bution." We must therefore search for some more peculiar and special combination of con- ditions before we can understand how Evolu- tion may result in great structural complexity. It is in the case of organic bodies " that these apparently contradictory conditions are recon- ciled ; and that, by the reconciliation of them, permanent secondary redistributions immense in extent are made possible." The distinctive peculiarity of organic bodies " consists in the combination of matter into a form embodying an enormous amount of motion at the same The statement of the law of evolution, as contained in the first edition, is much less complete and coherent. 211 COSMIC PHILOSOPHY time that it has a great degree of concentration." Let us enumerate the several ways in which organic bodies are enabled to retain vast quan- tities of molecular motion, without losing their high degree of concentration. The facts to be contemplated are among the most beautiful and striking facts which the patient interrogation of nature has ever elicited. In the, first place, while one of the four chief components of organic matter is carbon, a solid substance which cannot be fused by the greatest heat that man can produce, the other chief com- ponents — oxygen, hydrogen, and nitrogen — are gases which human art is unable to liquefy.1 At a temperature of more than 200 degrees below the zero of Fahrenheit, and under a pres- sure so enormous as to shorten the steel piston employed, oxygen remains gaseous ; and hydro- gen and nitrogen display a like obstinate mo- lecular mobility. Now, of these four substances, carbon has the most highly compounded mole- cule. In chemical language, the molecule of carbon is tetratomic, while that of nitrogen is triatomic, that of oxygen is diatomic, and that of hydrogen is monatomic. That is to say, a single molecule of carbon will hold in combina- 1 [The later success of liquefaction in these cases has be- come within a short time a well-known fact of popular science. Fiske's text here was of course accurate at the time of writ-' 212 THE LAW OF EVOLUTION tion two molecules of oxygen, or four molecules of hydrogen ; while three molecules of carbon will hold four molecules of nitrogen. It follows that in any organic compound, made up of the four above-named elements, a large number of molecules, possessing enormous mobility, must be held in combination by a relatively small number of molecules possessing little mobility. And since it is a corollary from the persistence of force that the sum of properties belong- ing to any compound must be the resultant of the properties belonging to its constituent elements, it follows that a compound molecule of organic matter must concentrate a great amount of motion in a small space. If, for ex- ample, we suppose ten molecules of carbon united with four of oxygen, eight of hydrogen, and eight of nitrogen, we shall have a com- pound in which ten immobile molecules hold together twenty highly mobile molecules. And while the twenty retain much of their mobility, the immobile ten prevent this mobility from disintegrating the compound. Here we have reached a most beautiful and marvellous truth. If we now proceed, secondly, to follow out the way in which these quantitative relations are compounded, the case will appear still more remarkable. Instead of tens and twenties, we have to deal with hundreds of inte- grated molecules. Instead of such hypothetical 213 COSMIC PHILOSOPHY cases as the one just cited, we have to contem- plate real cases like the following. A single molecule of albumen is built up of two mole- cules of sulphur and one of phosphorus, com- pounded with ten organic molecules, of which each one contains forty molecules of carbon, five of nitrogen, twelve of oxygen, and thirty-one of hydrogen. Or, to reduce the statement to its simplest form, — in every molecule of albu- men we have 1600 atomic equivalents of car- bon, 150 of nitrogen, 240 of oxygen, 310 of hydrogen, 10 of sulphur, and 6 of phosphorus ; making a grand total of 2316 atomic equiva- lents. And the molecule of fibrine is still more intricately compounded. Thirdly^ when we recollect that the simplest organic matter actually existing contains not one but very many albuminous molecules, and that these molecules are arranged, not in the crystalloid, but in the colloid form, — in " clus- ters of clusters which have movements in rela- tion to one another," — we see still more clearly how vast must be the quantity of motion locked up within a small compass. Our fourth item is perhaps the most remark- able of all. In the albumen molecule, the sum of all the atomic equivalents, except those of carbon, is 716. In order to hold these in com- bination, only 716 atomic equivalents of carbon would appear to be needed ; yet we find 1600 214 THE LAW OF EVOLUTION equivalents. Why this apparent excess of car- bon ? The answer is to be found in the fact that nitrogen, unlike most other substances, ab- sorbs heat on entering into combination. To the molecular motion which keeps it when free in a gaseous state, it adds a vast quantity of molecular motion. It has been calculated that the union of a pound of oxygen with nitrogen, in forming nitrous oxide, is attended by the ab- sorption of enough heat to raise the tempera- ture of 9232 pounds of water one degree Cen- tigrade. It is probably owing to this peculiarity that nitrogen, which is so inert when free, is so wonderfully active when combined. Hence, too, we may understand the extreme instability of such nitrogenous substances as gunpowder, gun-cotton, and nitro-glycerine. And hence we may begin to discern the reason why nitrogen is the most important of the chemical elements concerned in maintaining vital activity. Now when we compare this property of nitrogen with the apparent excess of carbon in the albu- men-molecule, we may fairly surmise that the two facts indicate a balance between the forces that tend to produce internal rearrangement and the forces that tend to prevent disintegration. Fifthly , besides the fact that organic bodies usually possess an amount of heat which keeps their temperature somewhat above that of their inorganic environment, we have to note the fact 215 COSMIC PHILOSOPHY that all organic matter is permeated by water. Hence, while sufficiently solid to preserve their continuity of structure, organic bodies are suffi- ciently plastic to allow of much internal rear- rangement. If we had time, it would be interesting to go on and trace the facts just enumerated through many complex exemplifications, and we might comment at length upon the significance of the facts that certain animals, as the Rotifera, lose their vitality when dried and regain it when wetted ; that vital activity everywhere demands a supply of heat, and that the most complex organisms are in general the warmest ; that ani- mals contain more nitrogen than plants, and are at the same time more highly evolved ; that carnivorous animals are relatively stronger and more active than herbivorous animals ; that the parts of animals which are the seats of the high- est vitality are mainly nitrogenous, while the more inert parts are mainly carbonaceous ; that the highly nitrogenous matter composing the nervous system is nevertheless — as if to pre- serve the balance — always accompanied by inert carbonaceous fat ; and that, while a nitro- genous diet renders possible the greatest quan- tity of physical and mental activity, at the same time carbonaceous alcohol retards the waste of nervous tissue. But even without entering upon such a 216 THE LAW OF EVOLUTION course of illustration — which would oblige us to defer our main subject until another occasion — we are now enabled to see how it is that or- ganic bodies can practically solve the dynamic paradox of acquiring a high degree of concen- tration, even while retaining an immense amount of motion. We are prepared to find, under these quite peculiar conditions, the structural rearrangements characteristic of Evolution car- ried on to a great extent. And we need not be surprised at finding these secondary phenomena here displayed so conspicuously as to obscure the significance of the primary phenomenon, integration. It was, in fact, through the study of organic phenomena by physiologists that a formula .was first obtained for the most con- spicuous features of Evolution ; while the less obtrusive but more essential feature not only remained unnoticed until Mr. Spencer discerned it, but was not adequately treated even by him previous to the publication of his rewritten " First Principles," in 1867. I think it there- fore advisable, in dealing with the law as gen- eralized from organic phenomena, to begin by describing these most conspicuous features. We shall thus obtain a clearer view of the whole subject than we could well obtain in any other way. Having shown that Evolution is always and primarily an integration of matter attended by a dissipation of motion ; and having shown 217 COSMIC PHILOSOPHY that under certain conditions, most completely realized by organic bodies, certain secondary but equally important phenomena of structural rearrangement may be expected to accompany this fundamental process ; we must next show what these secondary phenomena are. The exposition will be rendered clearer by the preliminary explanation of four technical terms, which will continually recur, and which must be thoroughly understood before any fur- ther step can be taken toward comprehending the Law of Evolution. These terms are neither obscure in themselves, nor newly coined, but because we shall henceforth employ them in a strict and special sense, they require careful de- finition. I. An object is said to be homogeneous when each of its parts is like every other part. An illustration is not easy to find, since perfect homogeneity is not known to exist. But there is such a thing as relative homogeneity ; and we say that a piece of gold is homogeneous as compared with a piece of wood ; or that a wooden ball is homogeneous as compared with an orange. II. An object is said to be heterogeneous when its parts do not all resemble one another. All known objects are more or less heterogeneous. But, relatively speaking, a tree is said to be heterogeneous as compared with the seed from 218 THE LAW OF EVOLUTION which it has sprung ; and an orange is hetero- geneous as compared with a wooden ball. III. Differentiation is the arising of an unlike- ness between any two of the units which go to make up an aggregate. It is the process through which objects increase in heterogeneity. A piece of cast-iron before it is exposed to the air is relatively homogeneous. But when, by expo- sure to the air, it has acquired a coating of ferric oxide, or iron-rust, it is relatively heterogene- ous. The units composing its outside are un- like the units composing its inside ; or, in other words, its outside is differentiated from its in- side. IV. The term integration we have already partly defined as the concentration of the ma- terial units which go to make up any aggregate. But a complete definition must recognize the fact, that, along with the integration of wholes, there goes on (in all cases in which structural complexity is attained) an integration of parts. This secondary integration may be defined as the segregation, or grouping together, of those units of a heterogeneous aggregate which resem- ble one another. A good example is afforded by crystallization. The particles of the crystal- lizing substance, which resemble each other, and which do not resemble the particles of the solvent fluid, gradually unite to form the crys- tal, which is thus said to be integrated from 219 COSMIC PHILOSOPHY the solution. Integration is also seen in the rising of cream upon the surface of a dish of milk, and in the frothy collection of carbonic acid bubbles covering a newly filled glass of ale. Obviously as it is through differentiation that an aggregate increases in heterogeneity, so it is through integration that an aggregate increases in definiteness, of structure and function. But there is still another way in which integration is exemplified. Along with increasing hetero- geneity and definiteness of structure and func- tion, the evolution of an aggregate is marked by the increasing subordination of the various functions, with their structures, to the require- ments of the general functional activity of the aggregate. In other words, along with grow- ing specialization of parts, there is a growing cooperation of parts, and an ever - increasing mutual dependence among parts. An illustra- tion is furnished by the contrasted facts, that a slightly evolved animal, like a common earth- worm, may be cut in two without destroying the life of either part ; while a highly evolved animal, like a dog, is destroyed if a single artery is severed, or if any one of the viscera is pre- vented from discharging its peculiar functions. This third kind of integration is the process through which an evolving aggregate increases in coherence. And with this, our definition of 220 THE LAW OF EVOLUTION the factors which concur in the process of evo- lution is complete. We are now prepared to show inductively that wherever, as in organic aggregates, the con- ditions permit, the integration of matter and con- comitant dissipation of motion, which primarily constitutes Evolution, is attended by a continuous change from indefinite, incoherent homogeneity to definite, coherent heterogeneity of structure and function, through successive differentiations and in- tegrations. In illustration of this statement, let us describe first some of the differentiations, and secondly some of the integrations, which successively occur during the development of an individual organism. Two centuries ago the researches of Harvey on generation established the truth that every animal at the outset consists simply of a struc- tureless and homogeneous germ. Whether this germ is detached from the parent organism at each generation, as in all the higher animals, or only at intervals of several generations, as for example, in the Aphides or plant-lice, matters not to the general argument. In every case the primitive state of an animal is a state of relative homogeneity. The fertilized ovum of a lion, for instance, possesses at first no obvious char- acteristic whereby it can be distinguished from the fertilized ovum of a man, a dog, a parrot, or a tortoise. Each part of the germ-cell is, 221 COSMIC PHILOSOPHY moreover, as nearly as possible like every other part, in molecular texture, in atomic composi- tion, in temperature, and in specific gravity. Here in two ways we may notice how homo- geneity is eventually succeeded by heterogene- ity. In the first place all animal germs are homogeneous with respect to each other, while the animals developed from them present all kinds and degrees of diversity ; and, in the sec- ond place, each germ is homogeneous with re- gard to itself, while the creature developed from it is extremely heterogeneous. The vegetable world exhibits a state of things essentially the same, though less conspicuous in its contrasts. Starting from the homogeneous germ, we may follow out a parallel series of differentia- tions, resulting respectively in molecular rear- rangements of chemical elements and in molec- ular and molar modifications of tissues and or- gans. The chemical differentiations have been so well and so concisely described by Mr. Spen- cer that I cannot do better than cite the passage entire : " In plants the albuminous and amy- laceous 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 meta- morphosed into wax. In this place starch passes into one of its isomeric equivalents, sugar; 111 THE LAW OF EVOLUTION 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 distinguish as cork. And the more numerous compounds thus grad- ually arising initiate further unlikenesses by mingling in unlike ratios. An animal ovum, the components of which are at first evenly dif- fused among one another, chemically transforms itself in like manner. Its protein, its fats, its salts, become dissimilarly proportioned in differ- ent localities ; and multiplication of isomeric forms leads to further mixtures and combina- tions that constitute many minor distinctions of parts. Here a mass darkening by accu- mulation of haematine, presently dissolves into blood. There fatty and albuminous matters uniting, compose nerve-tissue. At this spot the nitrogenous substance takes* on the charac- ter of cartilage ; and at that, calcareous salts, gathering together in the cartilage, lay the foun- dation of bone. All these chemical differentia- tions slowly and insensibly become more marked and more multiplied." " The differentiations of tissues and organs are equally interesting. In the growth of any exo- genous stem, the outer layer, or bark, first be- comes distinguished from the woody interior. 1 First Principles, p. 334. 223 COSMIC PHILOSOPHY Then while the bark gradually becomes differ- entiated into the liber, made up of woody tissue, tnea green and corky envelopes, made up of parenchyma, and the epidermis, the interior be- comes differentiated into the pith, the medullary sheath, the woody layer, made up of bundles of greatly elongated cells, and the medullary rays, or what is called the silver grain in maple and oak. Meanwhile, between this heterogeneous bark and the heterogenous wood which it sur- rounds, there appears a zone of delicate cells, charged with dextrine and other assimilable mat- ter, and known as the cambium layer. At the same time differentiations are going on at the upper extremity of this complicated structure. Portions of the green envelope protrude from between the liber and the epidermis, accompa- nied by tough fibres sent forth partly by the liber and partly by the woody layer. While the green portions flatten out horizontally, the fibres ramify through them and serve to stiffen them ; and thus is developed the leaf, which, when mature, usu- ally exhibits a further differentiation between blade and petiole, while by a continuance of the same process stipules often appear at the base of the petiole. Nor is this the end of the story. For while the chlorophyll-cells that make up the upper stratum of the leaf-tissue remain densely crowded, and are often covered by a wax-like cuticle, making the upper surface smooth and 224 THE LAW OF EVOLUTION glossy ; the cells composing the lower stratum become- less and less crowded, until the result is a spongy surface, filled with innumerable pores, through which the moisture of the plant may be exhaled. Finally a differentiation arises between the axillary buds, some of which elongate into branches, repeating the chief characteristics of the stem, while others are developed under the still more heterogeneous forms of flowers, with their variously cleft calyx and corolla, and their variously compounded stamens and pistils. In the fertilized mammalian ovum the ear- liest step toward heterogeneity consists in the division and redivision of the nucleated embry- onic cell. As the cell-nucleus grows, by con- tinuous integration of the nutritious protoplasm in which it is embedded, it slowly becomes grooved, and ultimately divides into a pair of nuclei, about each of which is formed a cell-wall. This process continues until the entire yolk is absorbed, by which time it has become differen- tiated into a mulberry-like mass of cells. And these cells, at first all alike spherical or nearly so, become club-shaped or hexagonal or pointed, as the mass further consolidates and squeezes them together. A grand differentiation next occurs between the outer and inner portions of the yolk-mass : the outer cells become flattened and pressed together, so as somewhat to re- semble a mosaic pavement, and thus form a vol. n 225 COSMIC PHILOSOPHY peripheral membrane. As this membrane con- tinues to thicken by the integration of adja- cent materials, it differentiates into two layers, wrapped the one within the other, like two coats of an onion. The outer layer, or ectoderm, ab- sorbing larger quantities of nitrogenous matter than the other, is the one which by further im- mense differentiation is destined to produce the bony, muscular, and nervous systems ; while the inner layer, or endoderm, is destined to pro- duce the digestive apparatus. Between these two, by a further differentiation, arises a vascu- lar layer, the rudiment of the circulatory sys- tem. Now on the interior surface of the endo- derm appears a grooved channel, of which the edges gradually rise and fold over towards each other until joining they form a tube, — the primitive alimentary canal. At first nearly uni- form, this channel becomes slowly more and more multiform. Near the upper end it bulges so as to form a stomach, while the long lower portion, variously wrapped and convoluted, is differentiated into the small and large intestines. From various parts of the now heterogeneous canal there bud forth variously organized se- creting glands, — those which make saliva, and those which make gastric juice, bile-cells, pan- creatic cells, and intestinal follicles. While from the exterior coat of the endoderm, thus won- derfully transformed, there shoot out, near the 126 THE LAW OF EVOLUTION upper end, little flower-like buds, which by and by become lungs. In the intermediate or vascular layer, equally notable differentiations simultaneously occur. The vascular channels become distinguished as veins, arteries, and cap- illaries. " The heart begins as a mere aggre- gation of cells, of which the inner liquefy to form blood, while the outer are transformed into the walls." Presently the auricle, or chamber which receives blood, is differentiated from the ventricle, or chamber which expels it ; and still later a partition-wall divides first the ventricle and afterwards the auricle into two portions — one for the venous, the other for the arterial blood. Along with all these changes, parallel processes, too numerous to be more than hinted at, are going on in the ectoderm. Masses of nitrogenous cells here give rise to muscles, which ramify through the whole interior of the embryo ; and there to cartilaginous structures, in which deposits of earthy phosphate, harden- ing around certain centres, generate bone. The nervous system, first appearing as a mere groove upon the surface of the germinal membrane, finally exhibits an almost endless heterogeneity. First there is the difference between gray and white tissue, of which the first generates the pe- culiar kind of molecular motion vaguely termed nerve-force, while the latter transmits such mo- tion. Then there are the differences between 227 COSMIC PHILOSOPHY the nervous centres which, differently bundled together, make up the cerebrum, the cerebel- lum, the corpora quadrigemina, the medulla ob- longata, the spinal cord, and the sympathetic ganglia, each of which aggregates is extremely heterogeneous in itself. And then there are the innumerable differences entailed by the highly complicated connections established between one nervous centre and another, by the inos- culations of different sets of nerves with each other, and by the circumstance that some nerves are distributed upon muscles, others upon glands, and others upon ganglia. These must suffice as examples of differen- tiation. To go on until we had exhausted the series of differentiations which attend the evo- lution of a single individual would be to write the entire history of an organism — and thus to convert our philosophic discussion into a special scientific monograph. That history was long since thoroughly written by Von Baer. Following out the hints furnished by Lin- naeus, K. F. Wolff, Goethe, and Schelling, this illustrious embryologist announced in 1829 his great discovery that the progressive change from homogeneity to heterogeneity is the change in which organic evolution essentially consists. It was this formula which Mr. Spencer began, some twenty years later, to extend into the uni- versal law of evolution. But, far from having 228 THE LAW OF EVOLUTION anticipated the essential portion of Mr. Spen- cer's discovery, Von Baer's formula stands in much the same relation to it in which the spec- ulations of Copernicus stood with reference to the discovery of Newton. Just as Copernicus wras essentially in error in maintaining that the planets revolve in circular orbits, Von Baer was essentially in error in considering the process of differentiation as the fundamental charac- teristic of evolution, as well as in ignoring the process of integration. The whole foregoing exposition has shown, and the entire remainder of the exposition will still further convince us, that the fundamental characteristic of evolution is integration of matter with dissipation of in- ternal motion ; and that the change from homo- geneity to heterogeneity is but the secondary rearrangement which results wherever the re- tained motion is great enough to allow it. Still more, in ignoring the process of integra- tion, Von Baer failed to include in his formula that change from indefiniteness and incoherence to definiteness and coherence, which is equally important with the change from homogene- ity to heterogeneity. In the evolution of an organic germ, integration is just as essential a part of the whole process as differentiation. If the latter were alone to take place, the result would simply be a chaotic medley of organs and tissues. Both operations are requisite to 229 COSMIC PHILOSOPHY produce a system of organs capable of work- ing in concert. And if differentiation goes on, unattended by integration, in any part of the body, disease, and often death, is the result. Cancers and malignant tumours are merely in- definite results of differentiation, which, never becoming integrated into harmony with the rest of the organism, end by maiming and finally destroying it. As Dr. Beale has shown, a cancer is a new variety of cellular tissue, fun- goid in character, which grows at the expense of the organism, and eats it up as effectually as a carnivorous enemy could eat it. To -employ an instructive metaphor, a cancer is a rebellion within the organism, — a setting up of an inde- pendent centre of government, — a fatal inter- ference with the subordination of the parts to the whole. Yet the organism in which a cancer has begun to grow is more heterogeneous than the healthy organism. In like manner the first stages of decomposition increase the heteroge- neity of the organism as a whole ; but because each new retrograde product follows henceforth a career of its own, free from the control of the organic aggregate, the result is not evolution, but dissolution. The differentiations which occur during the normal growth of the germ differ from those which constitute cancer and gan- grene, alike in their common subordination to the primary process of growth, and in the defi- 230 THE LAW OF EVOLUTION niteness of the resulting structures. " 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 as they accumulate, they simultaneously diverge from it, and consolidate into an organ. The anterior segments of the cerebro-spinal axis, which are at first continuous with the rest, and distinguished only by their larger size, undergo a gradual union ; and at the same time the resulting head folds into a mass clearly marked off from the rest of the vertebral column. The like process, variously exemplified in other organs, is meanwhile ex- hibited by the body as a whole — which be- comes 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." Mr. Spen- cer, from whom I have quoted this embryo- logic illustration, goes on to cite parallel in- stances in the development of lower forms of animal life ; a few of which may be here epi- tomized. In the growth of the lobster from its embryo, a number of calcareous segments, originally separable, become integrated into the compact boxes which envelop the organs of the head and thorax. A similar concentration 231 COSMIC PHILOSOPHY occurs in the spider, the bee, and the butterfly. In contrast with this, we may profitably observe what goes on in many annuloid worms, where the multiplication of segments by differentia- tion results in the fission of the animal into two distinct individuals, because the integrating power of the organism is slight.1 Similarly in 1 Here, without prejudice to the general argument, I may call attention to the very ingenious hypothesis propounded by Mr. Spencer, to account for the origin of the annulose or articulated sub-kingdom of animals. According to this hypo- thesis, any annulose animal is in reality a compound organism, each of its segments representing what was originally a distinct individual. In other words, an annulose animal is a colony or community of animals which have become integrated into an individual animal. Strong prima facie evidence of such a linear joining of individuals primevally separate is furnished by the structure of the lowest annelids. Between the successive seg- ments there is almost complete identity, both internal and external. Each segment is physiologically an entire creature, possessing all the organs necessary for individual completeness of life ; not only legs and bronchiae of its own, but also its own nerve-centres, its own reproductive organs, and frequently its own pair of eyes. In many of the intestinal worms each seg- ment has an entire reproductive apparatus, and being herma- phrodite, constitutes a complete animal. Moreover in the devel- opment of the embryo the segments grow from one another by fission or gemmation, precisely as colonies of compound animals grow. At the outset the embryo annelid is composed of only one segment. The undifferentiated cells contained in this seg- ment, instead of being all employed in the formation of a heterogeneous and coherent structure within the segment, as would be the case in an animal of higher type, proceed very 232 THE LAW OF EVOLUTION the development of the higher crustaceans, the parallel chains of ganglia, which constitute the soon to form a second segment, which, instead of separating as a new individual, remains partially attached to the first. This process may go on until hundreds of segments have been formed. Not only, moreover, does spontaneous fission occur in nearly all the orders of the annul ose sub-kingdom, but it is a familiar fact that artificial fission often results in the formation of two or more independent animals. So self-sufficing are the parts, that when the common earth-worm is cut in two, each half continues its life as a perfect worm, — as is above ob- served, in the text. Very significant, too, is the fact that in some genera, as in chastogaster, where the perfect individual consists of three segments, there is formed a fourth segment, which breaks off from the rest and becomes a new animal. All these facts, together with many others of like implica- tion, point to the conclusion that the type of annulosa has arisen from the coalescence, in a linear series, of little sphe- roidal animals primevally distinct from one another. How are we to explain, or classify, such a coalescence ? May we not most plausibly classify it as a case of arrested reproduction by spontaneous fission ? In other words, whereas the aboriginal annul oid had been in the habit of producing by gemmation a second individual which separated itself at a certain stage of growth, there came a time when such separation became ar- rested before completion ; so that, instead of a series of inde- pendent organisms, the result was a colony of organisms linked together in a linear chain. Let us observe that by this brilliant explanation the origin of the annulose type is completely assim- ilated to the origin of the lowest animal and vegetal types. The primordial type alike of the vegetable and of the animal is a single spherical or spheroidal cell, which reproduces itself by spontaneous fission. That is, it elongates until room is made for a second nucleus, after which a notch appears in the *33 COSMIC PHILOSOPHY nervous system of the embryo, unite into a single chain. The same kind of integration may be traced in the nervous systems of insects ; and the reproductive system of the vertebrata cell-wall between the nuclei ; and this notch deepens until the old and new cells are quite separated from each other. Now when many such primordial cells are enclosed in a common membrane, so that, instead of achieving a complete separation, they multiply into a jelly-like or mulberry-like mass, there is formed — whether the case be taken in the animal or in the vegetal kingdom — an organism of a type considerably higher than the simple cell. There is an opportunity for differently conditioned cells comprised in the same mass to become dif- ferently modified, and thus to subserve various functions in the economy of the organism. There is a chance for division and combination of labour among the parts. Now the progress achieved when the spheroidal members of an annuloid com- pound remain partly connected, instead of separating, is pre- cisely similar to this. Among the indubitably compound animals of ccelenterate or molluscoid type, in which the fission is not arrested, it is but seldom that the individuals stand related to one another in such a way that there can be any need of their severally performing diverse and specialized functions. For instance, among the hydrozoa, each member of the compound can get food for itself, can expand or contract its tentacles in any way without affecting the general welfare of the compound. But now, if the members of such a compound as the hypo- thetical primitive annuloid are grouped in a linear series, there must arise a difference between the conditions which affect the extreme members of the series, and the conditions which affect the intermediate members. And consequently there will ensue an advantage to the compound in the struggle for life, if the members, instead of continuing to perform identical functions separately, become sufficiently united to allow of their per- 234 THE LAW OF EVOLUTION furnishes like instances of coalescence which are so conspicuous that they are now usually made one of the primary bases of classification forming different functions in concert. Hence we obtain the lowest actual type of annul oid, in which the segments are mere repetitions of each other, with the exception of the extreme front and rear segments, which subserve different functions related to the welfare of the aggregate. Viewed in this light, the various great classes of the annulose sub-kingdom beautifully illustrate that progressive coordination of parts becoming more and more unlike one another, which is the chief characteristic of Evolution as displayed in the or- ganic world. In very low annelids, such as the intestinal worms, we see hardly any specialization among the parts ; and as we proceed upwards through the lower types, ending with the myriapoda, we meet with a great but varying number of segments, which show but little specialization save in the head and tail. The same is true in general of the larvae and cater- pillars of the higher types. But as we rise to the adult forms of the insect-group — comprising crustaceans, arachnoids, and true insects — we find the number of segments reduced to just twenty. And while this number remains unvarying, the mod- ifications undergone by different segments in conformity to the requirements of the aggregate are almost endless in. variety, the extremes, both of concentration and of specialization, being seen in the ant, the spider, and the crab. In many of the details of this gradual fusion of distinct individuals into a co- herent whole, we see the hypothesis interestingly illustrated and justified. In the annelids of low type, each segment has its own spiracles which have no internal communication with one another. On the other hand, in the insect-group there is a complete system of vessels connecting the respiratory sys- tems. While in the intermediate myriapoda we find, as might be, expected, a partial communication. 235 COSMIC PHILOSOPHY in this sub-kingdom. The reason why Von Baer overlooked this essential process is probably to be found in the fact that each secondary inte- gration, resulting in increased definiteness, serves to make the accompanying differentiation still more prominent. The differentiation of lungs, for instance, from the outer coat of the endo- derm, becomes marked in proportion as the flower-like buds become integrated into organs of definite contour. But while the two correla- tive processes go on hand in hand, it is none the less true that they are distinct processes, and that a comprehensive formula of evolution must explicitly describe them both. In further illustration of this twofold aspect of evolution, we may cite a fact which will by and by be seen to have other important bear- ings, but which may here serve as a valuable appendix to the foregoing discussion. This is the fact that, in ranking different organisms as high or low in the scale of life, we always pro- ceed chiefly with reference to the degree of heterogeneity, definiteness, and coherence which they exhibit. Those plants and animals which we rank as lowest in the scale are simply cells, like the homogeneous cells from which higher plants and animals are developed. So little spe- cialized are these forms that they do not exhibit even those characteristics by which we ordinarily distinguish between vegetal and animal life. As 236 THE LAW OF EVOLUTION we ascend the vegetal scale, we find the ferns and lichens decidedly more heterogeneous than the algae ; and as we meet with endogens and exo- gens, we find the increasing heterogeneity ac- companied by a definiteness and coherence of structure that is ever more and more conspicu- ous. Going up the animal scale, we find the annulosa, on the whole, much more heterogene- ous, definite, and coherent than the mollusca ; while the vertebrata, on the whole, exhibit these characteristics more strikingly than either of the other sub-kingdoms. The relatively homo- geneous and unintegrated polyps are ranked be- low all of these. Within each group the same principle of classification is universally followed. Contrast the centipede, whose multitudinous segments are almost literally copies of each other, or the earthworm, which may be severed in the middle and yet live, with the highly differentiated and integrated hive-bee, spider, or crab. Compare the definite and symmetrical contour of the cuttlefish, which is the highest of the mollusca, with the unshapely outline of the molluscoid ascidians. Or, to cite cases from the two extremes of the animal scale, consider first the complicated mammal, whose growth from the embryo we have lately contemplated ; and then turn to the hydra, or fresh-water polyp, which is a mere bag of organized matter, di- gesting with its inner surface and respiring with 237 COSMIC PHILOSOPHY the outer, — yet so little specialized that, if turned inside out, the digestive surface will be- gin to respire, and the respirative surface to digest, as imperturbably as if nothing had hap- pened. In short, in a survey of the whole organic world, progress from lower to higher forms is a progress from forms which are less, to forms which are more, differentiated and in- tegrated. One further point must be noticed before we conclude this preliminary sketch of the process of evolution. The illustrations above given refer almost exclusively to differentiations and integrations of structure, or, in other words, to rearrangements of the matter of which organic bodies are composed. It remains to be shown how the rearrangements of the motion retained by developing organisms exhibit the same char- acteristics, and manifest themselves as differ- entiations and integrations of function. All or- ganic functions are either molar motions of con- tractile muscles, or of circulatory fluids, or else they are molecular motions in nerves, or in secreting organs, or in assimilative tissues in general. To show how these various motions become more specialized and more consolidated as the organism is developed, let us briefly re- consider the case of the alimentary canal, whose structural modifications were lately described. The primitive alimentary canal exhibits from 238 THE LAW OF EVOLUTION end to end a tolerably uniform series of molar motions of constriction. But as the canal be- comes more heterogeneous, the molar move- ments in its different parts simultaneously be- come more unlike one another. While the waves of contraction and expansion remain constant and moderate throughout the small intestine, they are replaced in the oesophagus by more violent contractions and expansions that recur at longer rhythmical intervals. In the stomach the mechanical undulations are so much more powerful as to triturate the con- tained food, and their rhythms are differently compounded ; while the movements of the mouth are still further specialized in the actions of biting and chewing. In the molecular motions constituting secretion and absorption there is a similar specialization. While absorption is con- fined chiefly to the area covered by the lacteals, secretion is specialized in various localities — in the salivary glands, in the gastric and intes- tinal follicles, in the liver, and in the pancreas — and in each place it has acquired a peculiar character. A like increase in heterogeneity and definiteness marks the circulatory movements. In a slightly evolved animal the nutritive fluid, answering to blood, moves about here and there at seeming random, its course being mainly determined by the local pressure of the tissues. But in a highly evolved animal, which possesses *39 COSMIC PHILOSOPHY a well-developed vascular system, the blood runs in definite channels, and with well-marked differences of movement. Its movement is slow and continuous in the capillaries, fast and con- tinuous in the veins, still faster but discontinu- ous in the arteries ; while the rhythms in all are subordinated by the central rhythm of the heart. Still more remarkable, in the most com- plex organisms, is that kind of functional in- tegration which consists in the mutual depend- ence of different functions. Neither alimentation nor circulation nor respiration can go on alone ; and all three are dependent upon the continu- ance of nervous action, which in turn depends alike upon each of the three. A few whiffs of tobacco, for example, setting up slight molec- ular changes in the medulla oblongata, increase the heart's rate of pulsation, and stimulate every one of the alimentary secretions, while it is probable also that, through the medium of the sympathetic ganglia, the sectional area of every artery is slightly altered. The cautious phy- sician, in prescribing a powerful drug, knows that he is dealing with an integration of motions so extensive that the disturbance of any one will alter the directions and composition of all the others to a degree which baffles accurate calculation. Contrasting with such cases as these the homogeneous, indefinite and uncom- bined movements of those lowest animals, that 240 THE LAW OF EVOLUTION are borne hither and thither by the vibrations of cilia, it becomes evident that the formula which expresses the structural evolution of matter expresses also the functional evolution of the motion which the integrating matter retains. Embracing now in one general view the va- rious kinds of transformation exemplified in the present chapter, we find that our survey of organic development completely justifies Mr. Spencer's technical statement, — " Evolution is an integration of matter and concomitant dissipa- tion of motion, during which the matter passes from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity ; and during which the retained motion undergoes a parallel transfor- mation." ' Here, it will be observed, we have obtained a formula which applies not to organic devel- opment merely, but to the transformations of Matter and Motion in general. Though we have been led to it solely bv the consideration of those organic phenomena which, for reasons already presented, most conspicuously exem- plify it, and in connection with which it was first partially generalized by Goethe and Von Baer ; yet now that we have arrived at this formula, we find ourselves expressing it in terms that are universal. Instead of a mere law of biology, 1 First Principles, p. 396. tol. n. 24I COSMIC PHILOSOPHY we have enunciated the widest generalization that has yet been reached concerning the con- crete universe as a whole. Having ascertained that in organic aggregates, where the conditions are such as to allow of relatively permanent structural rearrangements, the process of Evo- lution is characterized by a change from in- determinate uniformity to determinate multi- formity, we have assumed that like conditions will everywhere be attended with like results. The law asserts that wherever a relatively per- manent system of rearrangements is possible, whether in organic or in inorganic aggregates, the change from indeterminate uniformity to determinate multiformity will be manifested. This leap of inference on Mr. Spencer's part, like the similar leap taken by Newton from the fall of the apple to the motions of the moon, is the daring act which completes the formation of the hypothesis. This grand hypothesis we must now proceed to verify by showing that the wid- est generalizations severally obtainable in the concrete sciences are included in it, and receive from it their common interpretation. It is to be shown that in the case of sundry inorganic ag- gregates or systems of parts (forming the sub- ject-matter of astronomy and geology), where circumstances not yet recounted permit the re- tention of a considerable relative motion of parts, the processes of differentiation and integration 242 THE LAW OF EVOLUTION are quite conspicuously manifested ; although, as we might expect, these processes are never carried so far here as in the case of organic ag- gregates. It will next be shown that the hypo- thesis is verified, alike by the scanty facts which are at our disposal concerning the genesis of Life, and by the enormous multitude of facts which prove beyond the possibility of doubt that the more complex living creatures have originated by physical derivation from ances- tral creatures that were less complex. Next, al- though — as I have already remarked — the phenomena of Mind are in no sense identifiable with material phenomena, yet as in all our ex- perience there is no manifestation of Mind which is not mysteriously conditioned by movements of matter, we shall find that these super-organic phenomena do not fail to conform to the uni- versal law. It will be shown that the develop- ment of conscious intelligence, alike in the in- dividual and in the race, is characterized bv the change from indeterminate uniformity to deter- minate multiformity. The history of the pro- ducts of conscious intelligence exemplify the same principle ; and nowhere shall we find more striking confirmation than is furnished by the phenomena of social progress. By the time we have narrated the results of this vast induction, we shall be convinced that " from the earliest traceable cosmical changes down to the latest 243 COSMIC PHILOSOPHY products of civilization," the law of organic evolution here expounded is the law of all evo- lution whatever. But the universality of this law admits of de- ductive proof which may properly be adduced while concluding this chapter, and before enter- ing upon the long course of inductive verifica- tion which comes next in order. Already we have seen that the changes which primarily con- stitute Evolution are necessitated by the rhythm of motion, and therefore indirectly by the per- sistence of force. We have now to show how the secondary changes, differentiation and inte- gration, are equally necessitated by the same primordial fact. It is a corollary from the persistence of force, " that, in the actions and reactions of force and matter, an unlikeness in either of the factors necessitates an unlikeness in the effects." When the different portions of any homogeneous aggre- gate are exposed to the action of unlike forces, or to unequal intensities of the same force, they are of necessity differently affected thereby. Between the unequally exposed parts there arise structural differences, entailing differences of property and function. That which before was homogeneoushasbecome heterogeneous through the appearance of certain unlikenesses, — and, under the name of differentiation, the rise of such unlikenesses has already been described. 244 THE LAW OF EVOLUTION It remains to be observed that such unlikenesses cannot but arise, that differentiation must needs take place, because it is impossible for all the parts of any aggregate to be similarly conditioned with reference to any incident force. Whether it be the mechanical vibrations caused by a blow, the slow undulations constituting heat, or the more rapid undulations constituting light, that are propagated through any body, it equally follows that the respective vibrations will be communicated in different degrees to those particles which are situated on the nearer and on the farther side of the body, and to those particles which are laterally near to or re- mote from the line followed by the incident force. The different parts will be variously moved, heated, or chemically affected, and a series of differentiations will thus have arisen. We need go no farther than the kitchen, to perceive that the crust formed on a loaf of bread or a joint of roasted meat, is due to the necessary unequal exposure of outside and in- side to the incident force coming in the shape of heat from the walls of the oven. In the im- possibility of balancing an accurately made pair of scales, in the equal impossibility of keeping a tank of water free from currents, in the rust- ing of iron, and in the uneven cooling of a heated metal, is exemplified the principle that the state of homogeneity is an unstable state. H5 COSMIC PHILOSOPHY Universally the tendency of things, amid the conflict of unlike forces, is toward heteroge- neity. Coincident with the differentiation of aggre- gates, there is a differentiation of the incident forces. When a moving body is broken up by collision, its original momentum is severed into a group of momenta, which differ both in amount and in direction. The ray of solar light which falls upon the foliage of a tree and upon the wall of the brick building behind it, is sep- arated by reflection into red and green rays, in which the undulations differ both in height and in breadth. Each portion of the differentiated force must in its turn enter as a factor into new differentiations. The more heterogeneous an aggregate becomes, the more rapidly must dif- ferentiation go on ; because each of its com- ponent units may be considered as a whole, bearing relations to the other units similar to those which the aggregate bears to other aggre- gates ; and thus the differentiation of the whole must be followed by the differentiation of the parts. There must thus be a multiplication of effects as heterogeneity increases ; because, with increasing heterogeneity, the forces which bod- ies and parts of bodies mutually exert upon each other must become ever more varied and complex in their amounts and directions. We may see, therefore, that differentiation is 246 THE LAW OF EVOLUTION a necessary consequence of the fundamental re- lations of matter and motion. And the same is true of that secondary integration or union of like units, which serves to render differentiation more conspicuous by substituting a demarcated grouping for a vague one. Considering what happens when a handful of pounded sugar, scattered before the breeze, falls here and there according to the respective sizes of the frag- ments, — we perceive that the units which de- scend in company are those of equal size, and that their segregation results from their like re- lations to the incident force. The integration of several spinal vertebrae into a sacrum, as the result of exposure to a continuous strain in the same direction, is a still better example ; and from the phenomena of morphological devel- opment many parallel cases might be cited. Wherever different parts of any group of units stand in different relations to an incident force, differentiation must result ; and wherever any sub-group of these units, after becoming unlike the rest, is acted on by a common force, the re- sult must be the integration of the sub-group. But manifestly the primary process of consol- idation cannot long go on in any aggregate, without bringing sundry groups of units into dissimilar relations to adjacent groups ; nor can it long go on without subjecting each group, thus differentiated, to a predominant force ex- 247 COSMIC PHILOSOPHY erted by the totality of the companion groups. Hence the change from indefinite incoherent homogeneity to definite coherent heterogeneity must accompany the integration of matter ; and no alternative conclusion can be reached with- out denying the persistence of force. I am aware that scanty justice is here done to the arguments by which, in three interesting chapters, Mr. Spencer establishes this deductive conclusion. But since the brief exposition here given is not intended as a substitute for the study of Mr. Spencer's treatise, but rather as a commentary upon it, his position has been per- haps sufficiently indicated. We are now prepared to study with profit some of the phenomena presented by the past history of our planetary system. In the evolu- tion of the sun, with his attendant planets and satellites, from a vast primeval mass of vapour, we shall be called upon to witness a grand illus- tration not only of that integration of matter and concomitant dissipation of motion which is the fundamental characteristic of Evolution in general, but also of that change from indefinite and incoherent homogeneity to definite and co- herent heterogeneity which is its most striking derivative feature. 248 CHAPTER V PLANETARY EVOLUTION1 AMONG the notable phenomena presented by the structure of our planetary sys- ^ tern, there are some which have become so familiar to us that we commonly overlook them altogether, and through sheer inatten- tiveness fail to realize their significance. For example, all the planets revolve about the sun in the same direction, which coincides with the direction of the sun's own rotation upon his axis. All the planets, moreover, revolve in planes which are but slightly inclined to the plane of the sun's equator. Satellites conduct them- selves similarly with reference to their primaries. Every satellite revolves about its primary in the direction of the primary's axial rotation, and in a plane but little inclined to the plane of the primary's equator. Again, with the single inter- esting exception of Uranus — and possibly also of Neptune — all the planets, as well as the sun, rotate upon their axes from west to east, in the same direction with their orbital revolutions. And lastly, all the planets, both primary and 1 [See Introduction, § 16.] 249 COSMIC PHILOSOPHY secondary, move in elliptical orbits of small or moderate eccentricity. We are so accustomed to acquiesce in these facts, as if they were ultimate, that we seldom stop to consider them in their true light, as un- impeachable witnesses to the past history of the solar system. Yet as Laplace has shown, it is practically impossible that such harmonious re- lations should hold between the various mem- bers of the solar system, unless those members have had a common origin. The clue to that common origin may be sought in facts which are daily occurring before our very eyes. Every member of our planetary system is constantly parting with molecular mo- tion in the shape of heat. Our earth is inces- santly pouring out heat into surrounding space ; and, although the loss is temporarily made good by solar radiation, it is not permanently made good, — as is proved by the fact that during many millions of years the earth has been slowly cooling. I do not refer to the often-cited fact that the Arctic regions were once warm enough to maintain a tropical vegetation ; for this high temperature may well have been due to minor causes, such as the greater absorptive power of the ancient atmosphere with its higher percent- age of carbonic acid and ozone. Nor need we insist upon the alleged fact that extensive glaci- ation appears to have been unknown until a 250 PLANETARY EVOLUTION comparatively late epoch ; although glaciation, whether brought about by changes in the dis- tribution of land and sea or by a variation in the eccentricity of the earth's orbit, certainly does seem to imply a progressive dependence of the earth upon the supply of solar heat, due to the lowering of its own proper temperature. Such facts, however, are wholly inadequate to describe the primitive heat of the earth. The flattening of the poles being considerably greater than could have been produced by the rotation of a globe originally solid on the surface, it fol- lows that the whole earth was formerly fluid. And this conclusion, established by dynamical principles, is uniformly corroborated by the ob- served facts of geology. Now the fluidity of the entire earth, with its rocks and metals, implies a heat sufficient to have kept the planet incan- descent, so that it must have shone with light of its own, like the stars. Similar conclusions are indicated by the observed geologic features of Mars and Venus ; and in the case of the moon we shall presently see what a prodigious loss of heat is implied by the fact that the forces which once upheaved its great volcanoes are now quiescent. The sun, too, is pouring away heat at such a rate that, according to Sir John Herschel, if a cylinder of ice 184,000 miles in length and 45 miles in diameter were darted into the sun every second, it would be melted 251 COSMIC PHILOSOPHY as fast as it came. Or, as Mayer has calculated, the amount of heat lost every minute by the sun would suffice to raise the temperature of thirteen billion cubic miles of water one degree Centigrade. Although this prodigious loss is perhaps partly compensated by heat due to the arrested motion of meteors falling upon the sun's surface, yet it is by no means probable that it is in this way compensated to any note- worthy extent. It is in every way indisputa- ble that from time immemorial sun, moon, and earth, as well as the other members of our sys- tem, have been parting with their internal mo- tion, in the shape of heat radiated into sur- rounding space. Thus in the history of our planetary system we may already begin to witness that dissipation of motion which has been shown to be one of the prime features of the process of Evolution, wherever exemplified. But, as we have also seen, the dissipation of motion is always and necessarily accompanied by the concentration of matter. It is not simply that, with two or three apparent exceptions, which have no bear- ing upon the present argument, all cooling bodies diminish in size and increase in density ; but it is also that all contracting bodies gener- ate heat, the loss of which, by radiation, allows the process of contraction to continue. In any contracting mass the particles which tend to- 252 PLANETARY EVOLUTION ward the common centre have their molar mo- tions constantly opposed by friction upon each other, and most of the motion thus arrested is converted into heat. If this heat is lost by radi- ation as fast as it is thus generated, the contrac- tion of the mass will go on unceasingly. It is in this way that physicists now account for the internal heat of the sun and the planets. A diminution of the sun's diameter by the amount of twenty miles could not be detected by the finest existing instruments ; yet the arrest of motion implied in this slight contraction would generate enough heat to maintain the present prodigious supply during fifty centuries. And in similar wise the internal heat of the earth dur- ing a given moment or epoch must be chiefly due to that very contraction which the radiation of its heat during the preceding moment or epoch has entailed. The generation of all this heat, therefore, which sun and planets have from time imme- morial been losing, implies the transformation of an enormous quantity of molar motion of contraction. It implies that from time imme- morial the various members of our planetary system have all been decreasing in volume and increasing in density ; so that the farther back in time we go, the larger and less solid must we suppose them to have been. This is an inevi- table corollary from the companion laws thatcon- *S3 COSMIC PHILOSOPHY tracting bodies evolve heat, and that radiating bodies contract. Obviously, therefore, if we were to go back far enough, we should find the earth filling the moon's orbit,1 so that the matter now compos- ing the moon would then have formed a part of the equatorial zone of the earth. At a period still more remote, the earth itself must have formed a tiny portion of the equatorial zone of the sun, which then filled the earth's orbit. At a still earlier date, the entire solar system must have consisted simply of the sun, which, more than filling Neptune's orbit, must have consisted of diffused vaporous matter, like that of which the irresolvable nebulae have recently been proved to consist. Now in the slow concentra- tion of the matter constituting this solar neb- ula, as both Kant and Laplace have elaborately proved, the most prominent peculiarities of the solar system find their complete explanation. Supposing the sun to have been once a mass of nebulous vapour, extending in every direction far beyond the present limits of the solar sys- 1 It is not presumed, however, that the moon's orbit was originally so large as at present. For by its tidal action upon our oceans the moon exerts a drag upon the earth's rotation, and the motion thus lost by the earth is added to the moon's tangential momentum, thus increasing the dimensions of its orbit. A precisely similar qualification is needed for the two next succeeding statements in the text. 254 PLANETARY EVOLUTION tern, these thinkers proved that the mere con- traction of such a mass must inevitably have brought about just the state of things which we now find. Let us observe some of the processes which must have taken place in this nebulous mass. Note first that we are obliged to accredit the various parts of this genetic neimla with mo- tions bearing some reference to a common cen- tre of gravity ; for the rotation of the resulting system must have had an equivalent amount of motion for its antecedent, and it is a well-known theorem of mechanics that no system of bodies can acquire a primordial rotation merely from the interaction of its own parts. In making this assumption, however, we are simply carrying out the principle of the continuity of motion. It is not necessary to suppose, in addition, that all these motions primordially constituted a ro- tation of the whole mass in one direction. Such a hypothesis seems to me not only gratuitous, but highly improbable. It is more likely that these primeval motions took the shape of cur- rents, now aiding and now opposing one an- other, and determined hither and thither accord- ing to local circumstances. In any case, such indefiniteness of movement must finally end in a definite rotation in one direction. For unless the currents tending eastward are exactly bal- anced by the currents tending westward — a sup- 1SS COSMIC PHILOSOPHY position against which the chances are as infinity to one — the one set must eventually prevail over the other. And after some such manner as this our solar nebula must have acquired its definite rotation from west to east. Let us next observe the mechanical conse- quences of this rotation. No matter what may have been the«primitive shape of the nebula — and, if we may judge from the analogy of irre- solvable nebulae now existing, it may very likely have been as amorphous as any cloud in a sum- mer sky — no matter what its primitive shape, it must at last inevitably assume the form pe- culiar to rotating bodies in which the particles move freely upon each other. It must become an oblate spheroid, flattened at the poles and bulging at the equator, because at the equator the centrifugal tendency generated by rotation is greatest. Furthermore, as the mass contracts it must rotate faster and faster ; for as the total quantity of rotation is unalterable, the velocity must increase as the space traversed diminishes. In accordance with these principles of me- chanics, as our solar nebula continued to radiate heat and contract, it continued to rotate with ever-increasing velocity, its poles became more and more flattened, and its equatorial zone pro- truded more and more, until at last the centri- fugal tendency at the equator became greater than the force of gravity at that place. Then 256 PLANETARY EVOLUTION the bulging equatorial zone, no longer able to keep pace with the rest of the mass in its con- traction, was left behind as a detached ring, gir- dling, at a small but steadily increasing distance, the retreating central mass. What must now have been the career of this detached ring? Unless subjected to absolutely- symmetrical forces in all directions — an infi- nitely improbable supposition — such a ring must forthwith break into a host of fragments of very unequal dimensions. For in order that it should break into equal-sized fragments, the strains exerted upon it must be disposed with absolute symmetry; and against this supposi- tion also the probabilities are as infinity to one. It would break, much as a dish breaks when dropped on the floor, into hundreds of frag- ments, of which some few would be relatively large, while the numerous small ones would vary endlessly in their sizes. At this stage, then, in- stead of a continuous ring, we have a host of satellites, surrounding the solar equator, revolv- ing in the direction of the solar rotation, and following each other in the same orbit. If un- disturbed by any powerful attraction from with- out, these fragments would continue in the same orbit, and would gradually differ more and more in their velocities. Each large fragment would, by its gravitative force, retard the smaller frag- ment in front of it, and accelerate the smaller VOL. II. ^57 COSMIC PHILOSOPHY fragment behind it, until at last two or three fragments would catch up with each other and coalesce. Thus, in the earliest case known to us, — that of the planet Neptune,1 — this pro- cess went on until all the fragments were finally agglomerated into a spheroidal body, having a velocity compounded of the several velocities of the fragments, and a rotation made up of their several rotations. Meanwhile the central mass of the vaporous sun continued to radiate heat and to contract, until, whenits periphery came to coincide with what is now called the orbit of Uranus, its cen- trifugal force at the equator again showed an excess over gravity, and a second equatorial belt was left behind ; and this belt, breaking up and consolidating, after the manner above described, became the planet Uranus. In like manner were formed all the planets, one after another ; and from the detached equatorial belts of the cooling and contracting planets were similarly formed the satellites. A very curious physical experiment, devised i It is not strictly impossible that there may be one or two planets exterior to Neptune, and therefore earlier in formation. Supposing the distances of such planets to conform, even as imperfectly as in Neptune's case, to the law of Titius, these distances must be so enormous as to prevent our readily dis- covering the planets, either directly by observation, or indi- rectly, by inference from possible perturbations of Neptune's movements. 258 PLANETARY EVOLUTION by M. Plateau, strikingly illustrates the growth of our planetary system from the solar nebula. M. Plateau's experiment consists in freeing a fluid mass from the action of terrestrial gravity, so that its various parts may be subject only to their own mutual attractions ; and then in im- parting to this mass an increasingly rapid move- ment of rotation. A quantity of oil is poured into a glass vessel containing a mixture of water and alcohol, of which the lower strata are hea- vier than the oil, while the upper strata are lighter. The oil, when poured in, descends un- til it reaches the stratum of the same density with itself, when being freed from the action of terrestrial gravity, and subjected only to the mutual attraction of its own molecules, it as- sumes a spherical form. By an ingenious me- chanical contrivance, M. Plateau now causes the sphere of oil to rotate about its own centre of gravity. While the movement is slow, the ex- cess of centrifugal force at the equator of the oil-globe causes a bulging of the equator and corresponding flattening of the poles, like that observed in the sun and in all the planets. From a sphere the oil-globe becomes a " sphe- roid of rotation." If now the movement is con- siderably accelerated, the equatorial portion of the oil-globe becomes detached, and surrounds the central sphere of oil in the shape of a nearly circular ring, like Saturn's ring-system. Finally, 259 COSMIC PHILOSOPHY if the movement is kept up for a sufficient length of time, the oil-ring breaks into fragments, which revolve like satellites about the oil-globe, and each of which keeps up for a time its own move- ment of rotation in the same direction with the revolution of the ring. The common origin of the planets from the sun's equator, as thus strikingly illustrated, ex- plains at once the otherwise inexplicable coinci- dence of their rotations, their revolutions, and their orbital planes. At a single glance we see why the planetary orbits are always nearly con- centric and nearly in a plane with the solar equator ; and we see that, since the sun must always have rotated, as at present, from west to east, the planets formed from him must have kept up a revolution, and acquired a rotation, in the same direction. Such is the grand theory of nebular genesis, first elaborated with rare scientific acumen by Kant in 1755, and afterwards independently worked out by Laplace in 1796. The claims of this theory to be regarded as a legitimate scientific deduction have been ably stated by Mr. Mill, in his "System of Logic," Book III. chapter xiv. As we are there reminded, " there is in this theory no unknown substance intro- duced on supposition, nor any unknown pro- perty or law ascribed to a known substance." Once grant that the sun and planets are cooling 260 PLANETARY EVOLUTION bodies, the inference is unavoidable that the matter which composes them was formerly much more rare and diffused than at present. If we are to infer the sun's past condition from its present condition, we must necessarily suppose that its constituent matter once occupied much more space than at present, " and we are en- titled to suppose that it extended as far as we can trace effects such as it might naturally leave behind it on retiring ; and such the planets are." The abandonment of successive equatorial zones by the shrinking solar nebula follows from known mechanical laws ; and the subsequent breaking up of each zone, and the consolida- tion of its fragments into a planet, are processes which similarly involve none but established dynamical principles. It equally follows, from elementary laws of mechanics, that the planets thus formed would revolve and rotate both in the directions and in the planes in which they are actually observed to revolve and to rotate. There is thus, observes Mr. Mill, nothing gra- tuitous in Laplace's speculation : " it is an ex- ample of legitimate reasoning from a present effect to a possible past cause, according to the known laws of that cause." But the evidence in favour of the theory of nebular genesis is not restricted to these general coincidences between observation and deduction. Many striking minor details in the structure of 261 COSMIC PHILOSOPHY the solar system, otherwise apparently inexpli- cable, are beautifully explained by the theory of nebular genesis. Let us first consider a case which would appear to be an obstacle, not only to this, but to any other framable theory. We have already hinted that Uranus, while revolv- ing in the same direction with the other planets, has a backward rotation, so that to an observer placed upon Uranus the sun would seem to rise in the west and set in the east. His moons revolve about him in the same retrograde direc- tion ; and his axis, instead of standing at a great angle to his orbit-plane, as is the case with all the nearer planets, lies down almost upon the orbit -plane. It has been asserted that these peculiarities are also manifested by Neptune — though our opportunities for observing the latter planet are so few that this point cannot yet be regarded as well established. Why now should such exceptional phenomena be mani- fested in the case of either or both of these out- ermost planets? In his essay on the Nebular Hypothesis, Mr. Spencer has shown that these phenomena may be explained by a reference to the shape of the rings from which the outermost planets were formed. When the solar nebula was so large as to fill the orbit of Neptune, its rotation must have been slower, and its figure consequently- less oblate, than at later stages of contraction. Now the ring detached from a very 262 PLANETARY EVOLUTION oblate spheroid, which bulges greatly at the equator, must obviously be shaped like a flat quoit, as is the case with Saturn's rings ; while conversely the ring detached from a spheroid which bulges comparatively little at the equator, will approximate to the shape of a hoop. Hence the rings which gave rise to Neptune and Uranus, having been detached before the solar nebula had attained the maximum of oblateness, are likely to have been hoop-shaped ; and when we consider the enormous circumferences occu- pied by these rings, compared with the moder- ate sizes of the resulting planets, we see that they must have been very thin hoops. Now in such a hoop the angular velocities of the inner and outer surfaces respectively will be nearly equal, and the planetary mass into which such a hoop concentrates will have its greatest diameter at right angles (or nearly so) to the plane of its orbit ; so that its tendency to ro- tate in the line of its revolution will be so slight as to be easily overcome by any one of a hun- dred possible disturbing circumstances. With- out feeling required to point out the precise nature of such circumstances, we may readily see that, in the case of the outermost planets, the causes which ordinarily make the rotation co- incide with the line of revolution were at their minimum of efficiency. So that this retro- grade rotation of Uranus, though not perhaps 263 COSMIC PHILOSOPHY actually implied by the hooped shape of its an- cestral ring, is at any rate quite in accordance with it. I cite this example, not merely on its own account, but also by reason of the further dis- closures to which it leads us. Whatever may be thought of the special interpretation just cited, there is no doubt that Mr. Spencer's con- ception of hoop-shaped and quoit-shaped rings points to a notable series of harmonies among the phenomena of the solar system. Observe, first, that according to the theory, the outer planets ought in general to be much larger than the inner planets ; and for a very simple reason. The ancestral rings which coincided with the immense orbits of Uranus and Neptune must of course have been larger than the ancestral rings which coincided with the smaller orbits of Mars and the earth. A ring, for example, which is seventeen thousand millions of miles in circumference may be expected to contain more matter than a ring which is less than six hundred millions of miles in circumference ; and hence we may understand why Neptune contains at least sixteen times as much matter as the earth. But this, though significant, is not a complete explanation ; for as the case now stands it would seem as if there ought to be a regular gradation in the sizes of the planets. Not only ought 264 PLANETARY EVOLUTION Mercury to be the smallest, but Neptune ought to be the largest. The facts, however, do not accord with this view. The four outer planets are indeed much larger than the four inner ones. But of the inner group the largest is not Mars, but the earth ; while in the outer group we find Jupiter three and a half times as large as Saturn, which in turn is seven times larger than Uranus. Now the key to these apparent anomalies must, I think, be sought in the shapes of the rings from which the planets were respectively formed. Neptune and Uranus, formed from very thin hoop-like rings, at a period when the solar equator protruded but slightly, are indeed large planets, but not so large as would be inferred from the size of their orbits alone. But as the solar nebula continued to contract, its increas- ing equatorial velocity rendered it more and more oblate in figure, so that the rings next de- tached were quoit-shaped. Hence the result- ing planets not only had their major diameters but little inclined to their orbit-planes, but they were also larger in size. The very broad quoits which gave rise to Jupiter and Saturn may well have contained more than fourteen times as much planetary matter as the extensive but slender hoops which formed the two oldest planets. If, instead of looking at the sizes of the resulting planets, we consider the thicknesses of the genetic rings, as determined by compar- 265 COSMIC PHILOSOPHY ing the size of a planet with the size of its orbit, we shall see that, from Neptune to Jupiter, there was a regular increase in the thickness of the rings, such as the theory might lead us to an- ticipate. But now after the separation of Jupiter from the parent mass, we encounter a break in this series of phenomena. The thickness of the de- tached rings sinks to a minimum in the case of the asteroids, and then steadily increases again till in Mercury there is once more an approach to the quoit shape. Observe the curious sequence of facts, which hitherto, so far as I know, has never been noticed by any of the writers who have treated of the nebular hypothesis. Since the mass of Mercury is four fifths that of Venus, while the circumference of his orbit is about one half that of the orbit of Venus, it follows that his ancestral ring must have been much thicker than that of Venus. Again, the earth is but little larger than Venus, while the cir- cumference of its orbit exceeds that of the lat- ter nearly in the ratio of five to three, so that it must have originated from a thinner ring. Mars, with an orbit exceeding the earth's in the ratio of eight to five, and containing but one eighth as much planetary matter as the earth, must have been formed from a still thin- ner ring. And since the asteroids, if all piled together, would not make a planet as large as 266 PLANETARY EVOLUTION Mars,1 while they move through a very much greater orbit, it follows that their parent-ring must have been the thinnest of all. In marvel- lous conformity to this general statement, it also happens that the inner planets rotate in planes which diverge more widely from their orbit-planes than in the case of Jupiter and Saturn, though less widely than in the case of Uranus and Neptune.2 And lastly let us note i It may be objected that we have probably not yet dis- covered all the asteroids. Those not yet discovered, however, must obviously be so small that the addition of them to the aggregated mass of those already known would not materially affect the truth of my statement. 2 Curiously enough, if we examine the different systems of satellites, we find a similar general contrast in size between the members of outer and inner groups. The two outer satellites of Jupiter are much larger than the two inner ones ; and the same relation holds between the four acknowledged satellites of Uranus ; while of the eight Sarurnian satellites, the four outer ones seem to be decidedly larger than the four inner ones. Moreover the largest of Jupiter's moons is not the outermost, but the third ; and of Saturn's moons the largest is not the eighth, but the sixth. To these interesting facts which Mr. Spencer has pointed out, I will add one which he has not ob- served. If instead of looking at the sizes of the moons, we consider the thicknesses of their genetic rings, as determined by comparing the size of a moon with the size of its orbit, we find in the Jovian system a regular increase in the thickness of the rings, from the outermost to the innermost. Similar evi- dence from the Saturnian system is not yet forthcoming, since the masses and even the volumes of Saturn's moons have not yet been determined with sufficient accuracy for this purpose. 267 COSMIC PHILOSOPHY that the velocities of the planetary rotations supply further confirmation ; for " other things equal, a genetic ring that is broadest in the direction of its plane will produce a mass ro- tating faster than one that is broadest at right angles to its plane ; " and accordingly Jupiter and Saturn, originating from relatively quoit- shaped rings, rotate very swiftly ; while all the inner planets, originating from relatively hoop- shaped rings, rotate with much less rapidity. Here we may profitably consider the singular instance in the history of the solar system in which a detached ring has failed to become in- tegrated into a single planetary mass. Every one remembers how, in accordance with the law of Titius concerning planetary intervals, Kepler was led to predict the existence of a planet be- tween Mars and Jupiter ; and how, at the be- ginning of the present century, not one only, but four such planets, were suddenly discovered. More than a hundred of these little bodies have now been detected, and each year adds new names to the list. The four earliest observed — Vesta, Juno, Ceres, and Pallas — are of respect- And concerning the Uranian system our knowledge is still more inadequate. It will be observed, however, that even the facts here fragmentarily collated point clearly to some com- mon mode of genesis for both planets and satellites ; and are likely, when completely generalized, to yield important testi- mony in behalf of the nebular theory. 268 PLANETARY EVOLUTION able dimensions ; Pallas having a diameter of 600 miles, or more than one fourth the diame- ter of our moon. Most of the others are quite tiny, the smallest having a surface perhaps not larger than the state of Rhode Island. Not only do they occupy the position which would normally belong to a single planet between Mars and Jupiter, but it is hardly questionable that they have all originated from a single ring ; for their orbits are interlaced in such a compli- cated way that, if they were material rings in- stead of ideal lines in space, it would be possible to lift them all up by lifting any one of them. Why should just one of the solar rings have failed to develop into a single planet, and why should such an arrest of development have oc- curred in just this part of the solar system ? According to Olbers, the discoverer of Pallas and Vesta, this is not a case of arrested devel- opment, but these little bodies are merely the fragments of an ancient well-developed planet, which has been in some way exploded. But this hypothesis, though countenanced by Mr. Spencer, seems to me unsatisfactory. In Mr. Spencer's essay, it is closely connected with the hypothesis of a gaseous nucleus for all the planets, which, though there ingeniously elabo- rated, seems to me as yet too doubtful to serve as a basis for further explanations. And even granting the hypothesis, it would be necessary 269 COSMIC PHILOSOPHY further to show why in this planet alone the out- ward pressure of the gaseous nucleus should have overcome the resistance of the solidified crust. I believe that the problem is much nearer a solution when we treat it as a case of arrested development ; for on this view the pe- culiar fate of the ancestral ring may be at least partially explained by a reference to the perturb- ing attraction exerted upon it by Jupiter. When we reflect upon the immensity of the distances which separate the outer planets from each other, even in conjunction, we perceive that during the earlier stages of nebular con- traction no planet was in danger of being dis- turbed in its formation by the attraction of its next outer neighbour and predecessor. But as the increasing equatorial protuberance of the solar spheroid began to result in the formation of larger and larger planets, and as the forma- tion of planets began, according to the law of Titius, to occur at shorter and shorter intervals, there began to be some danger of such disturb- ance. There was no chance for a catastrophe, however, until the time when the asteroid-ring was detached. The enormous Jupiter-ring was at least 3 70,000,000 miles removed from Saturn, besides which its huge mass, implying powerful gravitative force among its constituent parts, served further to ensure its equilibrium. Hence it ran little risk of incurring disaster in the 270 PLANETARY EVOLUTION course of its planetary development. It was otherwise with the ancestral ring of the aster- oids. This thinnest and weakest of rings started on its independent career at a distance of only 240,000,000 miles from Jupiter — the planet whose gravitative force is more than twice that of all the other planets put together. Under such circumstances it would seem impossible that a planet could be formed. The asteroid ring must have been liable to rupture, not only from the causes which affect all planet-forming rings alike, but also from the strain exerted upon it, now in one part and now in another, by Jupiter's attraction. The fragments of a ring, torn asunder by such a cause, would not con- tinue to occupy the same orbit — they would be dragged from the common path in various directions and to various distances, according to the ever-changing position of the disturb- ing body. Henceforward, instead of chasing directly on each other's heels, they would rush along in eccentric, continually intersecting paths, and there would thus be no opportunity for consolidation, except in the case of two frag- ments meeting each other at the intersection of their orbits. As a final result we should have, not one good-sized planet, but a multitude of tiny planets, with intersecting orbits exhibiting great differences in eccentricity. All this is true of the group of asteroids. While the mean 271 COSMIC PHILOSOPHY breadth of the ideal zone occupied by their orbits is about 100,000,000 miles, its extreme breadth reaches 250,000,000 miles. While the orbit of Europa is more nearly circular than any of the orbits of the true planets, on the other hand the orbit of Polyhymnia attains an almost cometary eccentricity, the difference be- tween its perihelion and aphelion being nearly 200,000,000 miles. There is one other circumstance, however, which my hypothesis thus far fails to explain. While the true planets revolve in planes but slightly inclined to the ecliptic — the orbit of Mercury showing an inclination of about seven degrees as the maximum instance — the aster- oids, on the contrary, revolve in planes of quite various degrees of inclination, the orbit of Pallas rising above the ecliptic at an angle of thirty- four degrees. As the disturbing attraction of Jupiter, however various in direction, would seem to have been exerted wholly in one plane, 1 am unable to account for this diversity of in- clinations. Yet in spite of this shortcoming in the hypothesis — which might perhaps be re- moved by some one more thoroughly conversant with dynamics — all the other circumstances in the case point unmistakably to the forcible rup- ture of the genetic ring by the attraction ex- erted by Jupiter ; and thus it would seem that, just when such an untoward event in the his- 272 PLANETARY EVOLUTION tory of the solar system might have been ex- pected to occur, it did occur. Supposing this explanation to be sound in principle, it is quite easy to show why such an event has not occurred subsequently. The next ring — the one which gave rise to Mars — must have been more than twice as thick as the genetic ring of the asteroids, and consequently better fitted to resist a strain from without. And, moreover, being 1 1 5,000,000 miles far- ther removed from Jupiter, the latter planet could exert upon it only four ninths of the dis- turbing force which it had exerted upon the asteroid-ring. Thus the Mars-ring was per- mitted to develop into a planet. In turn, the small size of Mars prevented him from exert- ing any disastrous perturbing force upon the ring which gave rise to the earth, though his distance from that ring could not have exceeded 50,000,000 miles. A simple computation will show that Mars could exert upon the earth- ring not much more than one hundredth part of the attraction exercised by Jupiter upon the ancestral ring of the asteroids. On the other hand, had the mass of Mars been one twenty- fifth as great as that of Jupiter — that is, thir- teen times as great as the mass of the earth — he might have prevented the formation of the planet on which we live. And had the mass of Mars been equal to that of Jupiter, he might vol. 11. -^73 COSMIC PHILOSOPHY have dealt destruction to all the planetary rings subsequently detached between himself and the present solar surface. The earth, Venus, and Mercury would in such a case have been repre- sented by a triple zone of asteroids, revolving in more or less eccentric orbits, and the por- tions of planetary matter which constitute the German armies beleaguering Paris might to- day1 have been peacefully whirling in space, ten million miles removed from the portions which constitute the starving population of that unhappy city. Joining together all the foregoing considera- tions, we have a most interesting array of facts, which I believe have not hitherto been contem- plated in connection with one another. Though in the sizes of the planets, superficially regarded, we find no conspicuous symmetry of arrange- ment, yet in the thickness of the genetic rings, as obtained by a legitimate process of inference, we find a symmetry of disposition that is strik- ing and suggestive. From Neptune to Jupiter we find a progressive increase in thickness that is entirely in conformity with the nebular hypo- thesis. From the asteroids to Mercury there is a similar progressive increase which is simi- larly in entire harmony with the hypothesis. And in the only group of satellites concerning which we have adequate data, there is observed 1 That is, in December, 1870. 274 PLANETARY EVOLUTION a parallel phenomenon. But in the solar sys- tem there is a conspicuous break in the uni- formity' of succession ; and this break curiously occurs just at the place where, according to the most plausible supposition, there was an arrest or failure in the normal formation of a planet. I have partially succeeded in tracing this arrest or failure to the immediate effects wrought by the mere proximity and gigantic size of the planet just preceding in the order of detach- ment. Whether it can be shown that this cause, which well-nigh accounts for one of this group of phenomena, will account in some analogous way for the whole group — whether it can be shown that the detachment of this gigantic mass may have altered the dynamic relations of the central spheroid in such a way as to re- duce to a minimum its power of eliminating fur- ther rings, I will not pretend to say. It seems to me better to leave the problem with this clear and definite statement, rather than to en- cumber it with hypothetical explanations which are quite likely to prove purely gratuitous. Of the various explanations which have occurred to me, none seem at all satisfactory ; and I will gladly resign, into abler hands, the task of solving the problem. What we may regard, however, as fairly established, is this, — that while, after the formation of Jupiter, the de- tachment of rings followed the same law of pro- 275 COSMIC PHILOSOPHY gression as before, there was nevertheless some newly introduced circumstance present which affected the whole series of detachments in com- mon. But while the non-explanation of this newly introduced circumstance leaves a serious gap in the argument, it is to be noted that all the facts, so far as collated, are in harmony with the nebular hypothesis, — the existence of the zone of asteroids, in particular, furnishing pow- erful evidence in its favour. If we pass from this complicated problem to the much simpler one of the distribution of the satellites, we shall find evidence in behalf of nebular genesis so remarkable as almost to amount to demonstration. Whoever has read the favourite speculations of theologians con- cerning the " plurality of worlds " will doubtless remember how strikingly the divine goodness is illustrated in the law that in general the remoter planets have the greater number of satellites. Here, however, as in so many cases, observes Mr. Proctor, " the scheme of the Creator is not so obvious to human reasoning as some have complacently supposed." The " contrivances " for lighting Saturn are by no means what they ought" to be, according to this teleological hy- pothesis. The illuminating power of our moon is (from its greater proximity to the sun) six- teen times greater than that of all the eight moons of Saturn combined ; while if that planet 276 PLANETARY EVOLUTION were habitable, his rings would prove a formi- dable nuisance. Mr. Proctor has shown that, in latitudes corresponding to that of New York and Naples, they cause total eclipses of the sun, which last seven terrestrial years at a time. But the problem which natural theology thus fails to solve is completely solved bv a verv simple mechanical consideration. Since the de- tachment of a moon-forming ring from a con- tracting planet depends on the excess of cen- trifugal force over gravity at its equator, it is evident that rings will be detached in greatest numbers from those planets in which the cen- trifugal force bears the highest ratio to gravita- tion. Such planets will have the greatest number of moons. And such, in fact, is the case. Of the four inner planets, which rotate slowly, and in which the centrifugal force is therefore small, only the earth is known to have a satellite.1 But Jupiter, whose centrifugal force is twenty times greater than that of any of the inner plan- ets, has four satellites. Uranus, with still greater centrifugal force, has at least four, and proba- bly six or eight moons. And finally Saturn, in which the centrifugal force is one sixth of grav- 1 It is not improbable that Venus may have a satellite also. Several astronomers have declared that they have seen such a satellite ; but as their testimony seems difficult to reconcile with that of other astronomers, equally competent as observers, the question must remain an open one for the present. 277 COSMIC PHILOSOPHY ity, being nearly fifty times greater than on the earth, has at least eight moons, besides his three unbroken (or partly broken) rings. Mr. Spen- cer may well declare that this emphatic agree- ment of observation with deduction is an un- answerable argument in favour of the nebular theory. Here, where the dynamic relations in- volved are so simple that we have no difficulty in tracing them, the significance of the result is unmistakable. Where we are enabled thus directly to put the question to Nature, there is no ambiguity in her answer. In the quoit-shaped rings which girdle Sat- urn, we have a curious vestige — upon the significance of which Kant strongly insisted — of the ancient history of our planetary system. So great has been the centrifugal fierce upon Saturn, due to his rapid rotation and small specific gravity, that the detachment of rings would seem to have gone on after the surface of the planet had assumed the liquid state ; and whether the rings thus formed be now continu- ous, or (as is far more probable) discontinuous, they have obvious-ly had a much better chance of preserving their equilibrium than the ordi- nary vaporous moon-forming rings. The dyna- mics of the Saturnian system still present many difficult questions ; but the fact that Saturn is the one planet which is still girdled by rings that are apparently continuous is a very pow- 278 PLANETARY EVOLUTION erful argument in favour of the nebular hypo- thesis. But* the evidence does not end with these mechanical illustrations. In the present physical condition of the various planets, so far as it can be determined, we shall find further corrob- orative testimony. It is a corollary from the nebular hypothesis that all the planets, having successively originated from the same vaporous mass, must be composed in the main of similar chemical elements ; and this inference has thus far been uniformly corroborated by spectro- scopic observation wherever there has been an opportunity to employ it. Hence it follows that the process through which the earth has passed in contracting to its present dimensions has been, or will be, repeated to a certain ex- tent upon all the other planets. Upon any planet there must eventually occur a solidifica- tion of the crust, an extensive evaporation and precipitation of water, an upheaval of moun- tains, an excavation of river-beds, and a deposit of alluvium, resulting in sedimentary strata. But obviously the time at which these pheno- mena occur must depend, not merely upon the antiquity of the planet, but also upon the rate with which it parts with the heat generated dur- ing its contraction. Since the outer planets are so much older than the inner ones, it might at first be supposed that they must have pro- 279 COSMIC PHILOSOPHY gressed much further in consolidation. But against this must be offset the consideration that the ratio of volume to mass is likely to have been from the first very much greater in the case of the earlier planets than in the case of the interior ones, since formed from a denser sun. Even now the high ratio of volume to mass is one of the most striking characteristics of the four outer as compared with the four in- ner planets ; and as bulky bodies radiate heat much more slowly than small ones, it may well be that this relatively small density indicates the retention of a relatively great amount of molecular motion. Of all the factors in the case, bulk is undoubtedly the most important. Just as the hot water in the boiler may remain warm through a winter's night, while the hot water in the tea-kettle cools off in an hour, so a great planet like Jupiter may remain in a liquid molten condition long after a small planet like the earth, though formed ages later, has ac- quired a thick solid crust and a cool tempera- ture. Hence in a general survey of the solar system we may expect to find the largest plan- ets still showing signs of a heat like that which formerly kept the earth molten, and we may ex- pect to find the smallest planets in some cases showing signs of a cold more intense than any which has been known upon the earth. Now this series of inferences, constituting 280 PLANETARY EVOLUTION simply an elaborate corollary from the theory of nebular genesis, is fully confirmed by ob- servation in the cases of Saturn, Jupiter, Mars, and the Moon, — the only planets whose sur- faces have been studied with any considerable success. According to the nebular hypothesis, Jupiter and Saturn ought to be prodigiously hot ; and so they appear to be when carefully examined. The tremendous atmospheric dis- turbances observed upon both these planets are such as cannot well be explained by the com- paratively sluggish action of the sun's radiance upon such distant orbs. The atmosphere of Jupiter is laden with masses of cloud, whether composed solely of water or not, whose cubic contents far exceed those of all the oceans on the earth. The trade-winds, due to the swift rotation of the planet, gather these enormous masses into belts parallel with its equator. Storms and typhoons are incessantly raging in this vapour-laden atmosphere ; and the forces at work there are so stupendous that dense cloud-belts, thousands of miles in width, are often formed in a single hour. This state of things is not like that which is now witnessed upon the earth's surface ; it is more like the state of things observed upon the sun, where tornadoes continually occur, in which the earth, if it were there, would be whirled along like a leaf in an equinoctial gale. A similar state of 281 COSMIC PHILOSOPHY things must have existed, in miniature, upon our own planet, in that primitive age when its oceans were in large part held suspended in the dense seething atmosphere, and when the in- tense volcanic fires within kept the surface in ceaseless agitation. In Saturn similar pheno- mena are witnessed. The appearance called the " square-shouldered figure " of Saturn, first ob- served by Sir William Herschel in 1805, has suggested the conclusion that the giant bulk of the planet " is subject to throes of so tre- mendous a nature as to upheave whole zones of his surface five or six hundred miles above their ordinary level." Whether this be really the case, — or whether, as Mr. Proctor more plausibly suggests, the prominences which give the square-shouldered aspect are due to the shoving up of immense masses of cloud far above the mean layer of Saturn's cloud-envel- ope, — we must equally recognize the presence of intense heat and furious volcanic action in the interior of that planet. When we add that re- cent calculations have made it almost certain that both Jupiter and Saturn are to some extent self- luminous, it becomes probable that these great planets still resemble their parent, the sun, more closely than they resemble their younger and smaller brethren. Very different is the state of things witnessed upon the moon. The absence of an atmosphere 282 PLANETARY EVOLUTION from the lunar surface was long since proved by the fact that " when stars are occulted by the moon, they disappear instantaneously," — which would not be the case had the moon an appre- ciable atmosphere ; and spectroscopic evidence has confirmed this conclusion. Nor are there any signs of the presence of liquid oceans, or of running water. Yet if the moon was origi- nally formed from an equatorial zone of the earth, it would seem that it ought to contain the same materials which have from the oldest times constituted a considerable part of the ter- restrial surface. Besides this, the vast plains on the moon which the old astronomers supposed to be seas, and named as such, are now held to be areas underlaid by sedimentary rocks im- plying the former presence of water.1 If this view be correct, there must in all probability have been winds to excite the erosive move- ments of the water which caused this sedimen- tation. For tidal action upon the moon cannot be regarded as a considerable factor in the ero- sion, unless we go back to that enormously re- mote period when the earth's tidal pull was still employed in dragging the moon's rotation into synchrony with its revolution. 1 Moreover, "it is not to be forgotten that, so far as ter- restrial experience is concerned, water is absolutely essential to the occurrence of volcanic action." Proctor, The Moon, P- 353- 283 COSMIC PHILOSOPHY Here there is an apparent discrepancy, which will disappear, however, when we inquire further into the past career of the moon as indicated by the present condition of its surface. To a great extent the lunar surface is made up of huge masses of igneous rock, through which at short intervals yawn enormous volcanic craters, whose fires seem to be totally extinguished. The giant forces required to bring about such a state of things are now quiescent. And this implies that the moon is a dead planet. It implies that the thermal energies which were once instrumental in raising those huge cones, Tycho, Copernicus, and the rest, — quaintly named after our terres- trial heroes of science, — and which once drove up fiery streams of molten lava through their ample mouths, are now clean gone, radiated off into space. This cessation of volcanic activity indicates that the planet has reached its limit of consolidation, and is no longer generating heat from within.1 Now the degree of cold implied 1 "Nevertheless, there are processes at work out yonder which must be as active, one cannot but believe, as any of those which affect our earth. In each lunation, the moon's surface undergoes changes of temperature which should suffice to disintegrate large portions of her surface, and with time to crumble her loftiest mountains into shapeless heaps. In the long lunar night of fourteen days, a cold far exceeding the intensest ever produced in terrestrial experiments must exist over the whole of the unilluminated hemisphere ; and under the influence of this cold all the substances composing the moon's 284 PLANETARY EVOLUTION by this stoppage of further lunar consolidation must immeasurably exceed anything within ter- restrial experience. It may well have been great enough to freeze all the lunar oceans, and even to liquefy, or perhaps to solidify, the gases of crust must shrink to their least dimensions — not all equally (in this we find a circumstance increasing the energy of the disintegrating forces), but each according to the quality which our physicists denominate the coefficient of expansion. Then comes on the long lunar day, at first dissipating the intense cold, then gradually raising the substance of the lunar crust to a higher and higher degree of heat, until (if the inferences of our most skilful physicists, and the evidence obtained from our most powerful means of experiment can be trusted) the surface of the moon burns (one may almost say) with a heat of some 5000 F. Under this tremendous heat all the substances which had shrunk to their least dimensions must expand according to their various degrees ; not greatly, indeed, so far as any small quantity of matter is affected, but to an important amount when large areas of the moon's surface are considered. Re- membering the effects which take place on our earth, in the mere change from the frost of winter to the moderate warmth of early spring, it is difficult to conceive that such remarkable contraction and expansion can take place in a surface presum- ably less coherent than the relatively moist and plastic sub- stances comprising the terrestrial crust, without gradually effect- ing the demolition of the steeper lunar elevations. When we consider, further, that these processes are repeated not year by year, but month by month, and that all the circumstances at- tending them are calculated to render them most effective be- cause so slow, steadfast, and uniform in their progression, it certainly does not seem wonderful that our telescopists should from time to time recognize signs of change in the moon's *ace." Proctor, The Moon, pp. 380-382. 285 COSMIC PHILOSOPHY the lunar atmosphere. The moon is indeed subjected at each rotation to the fierce noontide heat sent from the sun ; but however this may scorch and blister the rocky surface, it can exer- cise but little melting power. An atmosphere, as Mayer has happily observed, is like a valve which lets water run through in one direction, but not in the other. Through an enveloping atmosphere the solar rays easily pierce, but re- turn with difficulty. But from the airless surface of the moon the solar radiance must be imme- diately reflected into space, as from the surface of a polished mirror. Just as on the summits of the Himalayas, where the atmosphere is so rare, the huge snow masses remain through cen- turies unmelted, in spite of the sun's blazing heat ; so on the surface or in the deep abysms of the moon, the air and water once frozen must remain frozen forever. We have not yet, however, reached a satis- factory interpretation of the original disappear- ance of the lunar atmosphere. Granting the disappearance of the atmosphere, the mainte- nance of a more than arctic cold in spite of the utmost intensity of solar radiation may readily be admitted. But in this explanation the ab- sence of a surface atmosphere is presupposed rather than accounted for. Yet I have thought it worth while to introduce the case in this way, as we thus get a more vivid impression of 286 PLANETARY EVOLUTION the actual state of things upon the moon. For the original disappearance of the lunar air and water, a far more thoroughgoing explanation was propounded some years since by M. Sae- mann ; ' but in this explanation the extreme cooling of the moon, as just illustrated, is im- plicitly involved. According to M. Saemann's essay, the lunar air and water have been literally drunk up by the thirsty rocks. On our own globe the tendency of the surface-water is con- stantly to percolate through the soil of the land or sea-bottom, and thence through the rocks, downward towards the centre of the earth. Yet with our present supply of internal heat, it is not probable that any water can reach more than one hundredth part of the distance towards the earth's centre, without becoming vaporized and thus getting driven back towards the surface. In this way there is kept up a circulation of water through the peripheral portions of the earth's crust. But as the earth becomes cooler and cooler, the water will be enabled to circulate at greater and greater depths, thus materially lowering the level of the ocean. In this way, long before the centre has become cool, all the surface-water of the earth will have been sucked into the pores of the rocks, and a similar pro- 1 In a paper on the unity of geological phenomena through- out the solar system, translated by Professor Sterry Hunt, and published in the American Journal of Science, January, 1862. 287 COSMIC PHILOSOPHY cess will afterwards take place with the atmos- phere. M. Saemann shows that by the time the earth had reached complete refrigeration, the pores of the rocks would absorb more than one hundred times the amount of all the oceans on the globe, while room would still be left for the retiring atmosphere. Now this state of things, which will no doubt by and by be realized on the earth, would seem to be already realized on the moon. Being forty-nine times smaller than the earth, the moon has cooled with great rapidity, and its geologic epochs have been cor- respondingly short.1 After the moon, we are more familiar with the surface of Mars than with that of any other hea- venly body, the position of Venus being very unfavourable for thorough observations. Con- cerning the physical geography and meteoro- logy of Mars, some trustworthy information has been obtained. The distribution of land and sea over his surface is sufficiently obvious to be delineated in maps. He possesses liquid oceans, proved by spectroscopic evidence to consist of water, and his atmosphere is gaseous. That he 1 It should be added that the rapid cooling of the moon would greatly increase the porosity of its substance. Professor Frankland has shown that ** assuming the solid mass of the moon to contract on cooling at the same rate as granite, its refrigeration through only 1800 F. would create cellular space equal to nearly fourteen and a half millions of cubic miles." 288 PLANETARY EVOLUTION possesses climates analogous to our own might be inferred from the inclination of his axis to his orbit-plane, and is inductively proved by the fact that we can actually see his polar snows accumulate during the Martial winter and melt away at the approach of the Martial summer. Coincidences like these bear sufficient testimony to a general resemblance between Mars and the earth. For where there are oceans and clouds and an atmosphere and polar snows, there must also be currents, aerial and oceanic, as well as rains, rivers, and sedimentary rocks ; so that the surface of Mars must probably present geo- logic phenomena not essentially unlike those witnessed upon the earth. Whether such geo- logic similarity has entailed a further resem- blance in the case of organic and super-organic phenomena, must be left for the more profound deductive science of some future day to deter- mine. Thus from whatever point of view we study our planetary system, we find such a congeries of phenomena as would have been produced by the gradual development of the system from a homogeneous nebula. On summing up the con- spicuous facts already cited, we see that the neb- ular hypothesis fully explains the shapes of the planetary orbits, and their slight inclinations to the plane of the solar equator ; the shapes of the satellite-orbits, and their proximate coincidence vol. n. 289 COSMIC PHILOSOPHY with the equatorial planes of their primaries ; the inclinations of the planetary axes to their orbit- planes ; the oblate figures of the planets ; their velocities of rotation ; the directions in which they revolve ; and the directions in which they rotate. To this last clause the apparent obstacle presented by the retrograde rotation of Uranus (and possibly of Neptune also) is seen on closer examination to be no real obstacle ; and the fact that the exception occurs among the outermost planets, just where we might expect it to occur, if at all, is a powerful argument in favour of the general theory. A like .powerful argument is furnished by the existence of apparently con- tinuous rings about Saturn, the planet upon which the centrifugal force bears the highest ratio to gravity. Still more convincing is the tes- timony rendered by the distribution of satel- lites,— a testimony well-nigh meeting all the requirements of crucial proof. Irregular as are the sizes of the planets on a superficial view, we find beneath this apparent irregularity a marvel- lous symmetry of disposition, the explanation of which, though incomplete, is as far as it goes in favour of the nebular hypothesis. The breaking up of the zone of asteroids, though not fully explained, is seen to have occurred in the only part of the system where such an event, accord- ing to the hypothesis, was likely to occur. And finally the geologic or meteorologic phenomena 290 PLANETARY EVOLUTION manifested by the four planets whose surfaces have thus far been successfully studied are just what the theory requires them to be. The in- tense heat and furious volcanic activity of Ju- piter and Saturn, the extreme loss of heat and cessation of volcanic activity upon the moon, the moderate temperature and habitable aspect of Mars, are alike deducible from the nebular hy- pothesis. I doubt if such persistent agreement between deduction and observation has ever been wit- nessed in the case of an erroneous or radically inadequate hypothesis. If the sole ultimate test of a theory is that it reconciles the order of con- ceptions with the order of phenomena, may we not say that the theory of Kant and Laplace, having sustained the repeated application of this test, may be accepted provisionally as a true account of the past history of our system of worlds ? It is true that the application of the test has not yet been made exhaustive ; the veri- fication is not yet complete. Some of the inter- pretations above given are still, as I have ac- knowledged, but partial ; and there are yet other groups of phenomena with which I have not ventured to meddle. To the various densities of the planets I have alluded but incidentally ; and the various angular velocities, as well as the order of distances formulated in the law of Titius, still await an explanation. Besides which, 291 COSMIC PHILOSOPHY the evidence from the physical condition of the surfaces of Mercury and Venus, Uranus and Neptune, and the moons of the four outer plan- ets, is not yet forthcoming. It would be as- serting too much, therefore, to assert that the nebular hypothesis is completely verified, like the hypothesis of gravitation. But on the other hand, they understand little of the logic of sci- entific inquiry who expect to obtain the same kind and degree of evidence in the former case as in the latter. It was part of Newton's rare good fortune that his hypothesis was the gener- alization of a physical property of matter, which could be verified by a single crucial instance. In none of the concrete sciences can such kind of verification be looked for. A theory relating to a heterogeneous assemblage of concrete pheno- mena can only be verified gradually, as the suc- cessive groups of phenomena in question are one after another successfully studied and inter- preted. Thus the complete verification of the nebular hypothesis, as applied merely to the solar system, involves the complete explanation of the chief dynamic and physical features of the system ; and for this we have yet to wait. Meanwhile the theory possesses such unmis- takable marks of genuineness, it conforms in so many and various ways to the test of reconciling the order of conceptions with the order of phe- nomena, that no one capable of estimating sci- 292 PLANETARY EVOLUTION entific evidence would hesitate in provisionally accepting it. Devised to account for a certain limited group of phenomena, it not only ac- counts for these, but also for other groups of phenomena, not considered by its propounders. Facts which on a superficial view appeared as obstacles to the theory have on closer exami- nation turned out to be powerful arguments in its favour. It is sustained by all the facts within our ken, and invalidated by none. And it has so far thriven with the progress of discovery during the past hundred and twenty years, that at the present moment it commands wider as- sent than at any previous time since its first pro- mulgation. Of this last statement we find striking con- firmation as we pass beyond the limits of the solar system and seek for evidence in the re- motest depths of stellar space. It is well known that Sir William Herschel supposed certain ir- resolvable nebulae to consist of self-luminous vapour hovering cloud-like in space. Laplace associated this hypothesis with his own theory of planetary evolution ; pointing to the present existence of nebulous masses as confirmatory proof of the past existence of such a nebulous mass as his theory required. According to this view, the irresolvable nebulae are simply starry systems in embryo ; and when our planetary system consisted simply of the sun diffused in 293 COSMIC PHILOSOPHY gaseous form over a circumference of perhaps thirty thousand million miles, it was just like one of these nebulae. But since Herschel's time many nebulae, which he regarded as irresolvable, have been resolved into dense starry clusters. The great nebula in Orion, upon which Her- schel placed great reliance, was resolved both by Lord Rosse's reflector and by our Harvard refractor ; and the suspicion began accordingly to arise that, if our telescopes were only power- ful enough, there might prove to be no irre- solvable nebulae at all. Hence many writers thoughtlessly hastened to proclaim that the neb- ular theory had lost its chief support, forget- ting that the overwhelming evidence furnished by the comparatively well-known structure of the solar system must take precedence of any hypothesis as to the character of remote and less- known sidereal phenomena. Mr. Chambers, in giving an account of the resolution of the " dumb-bell " nebula in Vulpecula, rather glee- fully wrote the 'obituary of the nebular hypo- thesis ; but like many other obituaries, this one turned out to be premature. For now came Mr. Huggins, with his spectroscope, and proved once for all that the wary and sagacious Her- schel, who hardly ever made a false step, was right, here as elsewhere. In 1864 Mr. Huggins analyzed the light sent from a nebula in Draco, and found it to contain the bright lines which 294 PLANETARY EVOLUTION are sure evidence of the gaseous condition of the luminous body. Since then several other nebulas have been proved to be gaseous ; so that the question may now be regarded as settled for- ever, and as settled in favour of the nebular hy- pothesis. Henceforth, to the evidence found in the structure of our planetary system, there may be added the weighty argument that masses of matter still exist in space, in the very condition in which our system must have originally ex- isted. If the nebular hypothesis was ever to be sub- jected to a hazardous trial, one would suppose that the discovery of spectrum analysis must have furnished the occasion. Here is a discov- ery which has suddenly enlarged our knowledge of the stellar universe in a manner utterly be- yond the power of the greatest and subtlest mind to have predicted twenty years ago, — a discovery which not only reveals to us the actual motions of the stars, but even penetrates into their molecular structure, and discloses the chemical elements of which their surfaces are composed as well as the physical state of ag- gregation of those surfaces. Now if ever, one might think, is the time to find out whether our nebular hypothesis, devised in an era of comparatively scanty astronomical knowledge, is a sound hypothesis or not. If it survives this immense, unprecedented extension of our know- 295 COSMIC PHILOSOPHY ledge, what more magnificent triumph could we wish for it ? And here we see that the very first result of the application of spectrum analysis to sidereal phenomena has been the placing of the nebular hypothesis upon a firmer basis than ever before, removing the only serious obstacle which had hitherto deterred many cautious thinkers from committing themselves to it. Spectroscopic researches but lately under- taken, and not yet carried out to a decisive re- sult, seem likely not only further to strengthen the noble theory of Kant and Laplace, but to give it a comprehensive significance of which those great thinkers could never have dreamed. Along with further confirmation of the process of mechanical and physical evolution, as origi- nally formulated in their hypothesis, evidences are daily coming in to show that there is going on a parallel process of chemical evolution from homogeneity to heterogeneity, which is no less wonderful in its significance. The old empiri- cal classification of stars according to their col- ours is beginning to have a new meaning. The method of comparison is becoming applicable in astronomy, as it has long been employed in the study of organisms, of societies, and of lan- guages. It begins to be probable that among the various groups of stellar bodies there may be found cosmical matter in many different stages of evolution, — from the primitive nebula which 296 PLANETARY EVOLUTION yields but a simple hydrogen-line, to silch a highly evolved body as our own sun with the many lined vapour of iron abundant in its heated atmosphere. But into this fascinating region of speculation it would be somewhat premature for us now to enter. Merely indicating what a rich harvest of discovery is here likely to reward the labourers of the immediate future, I would call attention to an interesting speculation of Mr. Spencer's, the possible inadequacy of which need not weaken the effect of the evidence above cited from planetary phenomena, and which is in every way worthy of serious consideration. According to Mr. Spencer, the distribution of nebulae affords a significant illustration of the nebular hypothesis. Speaking generally, nebulae occur in regions where developed stars are scarce. The vast groups of spherical nebulae, here and there partly developed into starry clusters, which constitute the so-called Magellanic Clouds, are situated in a district of the sky that is other- wise starless. Now by far the most striking of this class of facts is one which serves to bring the entire sidereal system into direct comparison with that little portion of it to which we belong. Just as the planets lie almost entirely in a singie plane, so the stars are distributed in almost in- finite numbers in the plane of the Milky Way, while elsewhere they occur rarely. And just as the comets are chiefly distributed about the 297 COSMIC PHILOSOPHY polesf of our solar system, their orbits cutting its equatorial plane at great angles, so the neb- ulae are found in greatest numbers about the poles of the galaxy. It seems unlikely that this parallelism, which Mr. Spencer was the first to point out, should be accidental. It indicates a common mode of evolution of the whole starry system. It vaguely points to a gigantic pro- cess of concentration going on throughout the galaxy, analogous to the local process of con- centration which has gone on in our own little planetary group. Still more obvious will this become when we consider the explanation of these phenomena which Mr. Spencer has offered. Observation shows that while the more con- solidated nebulas are oval or spheroidal in shape, the less consolidated nebulae are often extremely irregular, throwing out long arms of vaporous matter into the adjacent spaces. This agrees with what we have learned to expect in any ro- tating mass which gravitation is slowly draw- ing closer and closer together. The oval form is due, as we have seen, to the combined effects of gravitation and rotatory movement. But this implies an earlier state in which the figure was irregular. Now while the heavier portions of the mass were being drawn together so as to acquire a spheroidal contour, the lighter por- tions, floating farther from the centre of gravity, would remain like detached shreds of cloud, or 298 PLANETARY EVOLUTION like long luminous streaks. And while all these would ultimately be compelled bv gravitation to revolve about the centre of the mass, never- theless the lightest and outermost shreds would be a long time in acquiring a definite direction of revolution. While the greater number would be doubtless drawn in and absorbed by the main mass at an early stage, the chances are that some would not arrive until the main mass had become considerably contracted. Now it is easy to see that such late arriving flocculi, com- ing toward the centre of gravity from a great distance, and therefore having small angular velocities, will move in very eccentric ellipses. In the next place, while they will come from all parts of the space which the mass originally occupied, they will come chiefly from regions remote from the plane in which integration has been most marked, — that is, from the poles of the nebula rather than from its equatorial regions. And thirdly, having failed to accom- pany the retreating mass of the nebula while it was first acquiring a definite direction of rota- tion, their own revolutions will be determined chiefly by their irregular shapes, and they will be as likely to be retrograde as direct. All this is true of comets : they come chiefly from high solar latitudes, along immensely ec- centric orbits, and in directions which are indif- ferently direct or retrograde. And when we add 299 COSMIC PHILOSOPHY that they are nebulous in constitution, it appears highly probable that they are simply outlying shreds of the nebula from which our planetary system has been developed. As for the irre- solvable patches of nebulous matter which are distributed about the poles of the galactic circle, their distance from us is so great that we have not yet ascertained anything trustworthy con- cerning their motions. But the fact that their position in high galactic latitudes is explicable upon the same general principles which explain the positions of comets, raises a presumption that their relation to the galaxy as a whole may somewhat resemble that which comets bear to the solar system. Between the possible careers of the nebulae and the comets, there is, how- ever, a mighty difference. The nebula which we see through quadrillions of miles shining by a light of its own must needs be an enormous object — enormous in mass as well as in vol- ume — and its gravitative force must be pro- portionate to its size. While, therefore, its grad- ual contraction is likely to be attended by its development into a planetary system, — by a process of integration and differentiation such as we have here described, — on the other hand the comet is an object of inconsiderable mass, though very often of considerable volume. The slight concentration of which it is capable will not produce planetary systems or even asteroids, 300 PLANETARY EVOLUTION but only streams of meteors or shooting-stars, such as are now poured down upon the earth and its neighbour planets at the rate of a hun- dred thousand million each year. The researches of the past ten years have gone far to show that such meteoric streams differ from nebulous com- ets in no respect save in their greater aggrega- tion ; the difference being similar to the differ- ence between a cloud and a shower of raindrops. We are constantly encountering portions of these condensed comets and uniting them with our own planetary substance. And in this way the integration of the outlying portions of our primitive nebula is, at this late day, still going on. As we pause to survey, in a single compre- hensive glance, this gigantic process of Plan- etary Evolution, in which the integration of matter and concomitant dissipation of molec- ular motion, kept up during untold millions of ages, has brought about the gradual transfor- mation of a relatively homogeneous, indefinite, and incoherent mass of nebular vapour into a decidedly heterogeneous, definite, and coher- ent system of worlds ; we are at first struck by the peculiarity that the process has apparently long since come to a close in the establishment of a complete moving equilibrium. Habituated as we are to the contemplation of fleeting phe- 301 COSMIC PHILOSOPHY nomena, the stars in their courses have become the types of permanence ; and the stability of our planetary system has furnished a fruitful theme for the admiring comments of the math- ematician and the theologian. In so far as this appearance of eternal stability is well founded, it admirably illustrates the theorem — already cited in our discussion of the rhythm of mo- tion— that wherever the forces in action are few in number and simple in composition, the re- sulting rhythms will be simple and long-endur- ing. Nevertheless the processes still going on in our system are such as to forbid the conclu- sion that this apparently permanent equilibrium is destined really to be permanent. The con- centration of matter and concomitant dissipa- tion of molecular motion, which has gone on from the beginning, must still continue to go on until it has reached its limit. That consolida- tion and accompanying refrigeration which has changed the earth from a nebula into an incan- descent star, and from a star into an inhabitable planet, must continue until a state of things is inaugurated for which we must seek a parallel in the present condition of the moon. So, too, the contraction which generates the prodigious quantity of heat daily lost by the sun cannot go on forever without reducing the sun to a solidity incompatible with the further genera- tion of radiant energy. 302 PLANETARY EVOLUTION Thus the moon appears to afford an example of the universal death which in an unimagina- bly remote future awaits all the members of the solar system. It then becomes an interest- ing question whether this cosmic death will be succeeded by Dissolution, — that is, by the re- diffusion of the matter of which the system is composed, and by the reabsorption of the lost motion or its equivalent. We shall find it diffi- cult to escape the conclusion that such a disso- lution must ultimately take place. If, along with the dissipation of molecular motion already described, the planets are also losing that molar motion to which is due their tangential momentum, this loss of motion must ultimately bring about their reunion with the sun. Upon such a point direct observation can help us but little ; but there are two opposing considerations, of a force which none will deny, and based on facts which none can dispute. Two sets of circumstances are struggling for the mastery, — the one set tending to drive the planets farther and farther away from the centre of the system, the other set tending to draw them towards the centre. Let us see which set must prevail in the end. Hitherto, in all probability, the first set of circumstances has had the advantage. There is little reason to doubt that all the planetary orbits, both primary and secondary, are some- 303 COSMIC PHILOSOPHY what larger now than they were originally. This is an indirect consequence of the slow loss of rotatory momentum due to tidal action. The calculation by which Laplace thought he had proved that the terrestrial day had not length- ened since the time of Hipparchos, has been shown by Professor Adams to be vitiated by the inclusion of an erroneous datum ; and the the- ory involved is no longer tenable. It has been proved that the tidal wave which the moon draws twice a day around the earth, in the op- posite direction to the terrestrial rotation, acts upon the earth like a brake on a carriage-wheel. Owing to this circumstance, the day is now one eighty-fourth part of a second longer than at the beginning of the Christian era ; and it is destined to continue lengthening until in the remote future there will be from three to four hundred hours between sunrise and sunset. But the rotatory momentum thus lost by the earth is not destroyed. In conformity with a well- known principle of dynamics, it is added to the tangential momentum of the moon, and thus lengthens the radius of the moon's orbit. The more slowly our planet rotates, the farther the moon retires from us. A similar relation holds good in the case of the planets and the sun. Not only is it demonstrable a priori that the planets must cause tides upon the surface of the sun, but the tides caused by all the primary 304 PLANETARY EVOLUTION planets, save Mars, Uranus, and Neptune, have been actually detected by a minute comparison of the variations in the solar spots. These tidal waves are drawn around the sun in the direc- tion opposite to that of his rotation, and must therefore exert a retarding effect. And the ro- tatory momentum thus stolen from the sun is added, in accordance with a pro rata princi- ple of distribution, to the tangential momenta of the various planets concerned in the theft. There can be little doubt, therefore, that all the planetary orbits, both primary and second- ary, are steadily enlarging, and that this pro- cess must go on until that synchrony between revolution and rotation now witnessed in our moon becomes universal, unless it is previously checked by the cessation of tidal phenomena. As between the earth and moon, for example, the ultimate result of the whole process must be the lengthening of the terrestrial day until it corresponds with a lunar month, so that the earth and moon will move in relation to each other just as if joined together by a rigid rod. This result will actually be realized unless fore- stalled by the completed refrigeration of the earth, which will put an end to the tidal friction. In like manner the sun's rotation must dimin- ish until equilibrated with the motions of the planets, unless this result is forestalled by the completed refrigeration of the sun. And in all vol. n. 3^5 COSMIC PHILOSOPHY cases, so long as the process goes on, there must be a tendency, however slight, for the planets to recede from the sun. The action of this set of circumstances, how- ever, though hitherto no doubt predominant, is strictly limited in duration. Sooner or later an equilibration of motions will be reached, and this receding tendency will cease to be mani- fested. It is quite otherwise with the opposing set of circumstances which we have now to con- sider. We have now to contemplate a cause which operating from the very outset, and still insidiously operating, will continue to operate long after the process just described has come to an end. Each year's discoveries show more and more conclusively that the interplanetary spaces are filled with matter. The existence of some interplanetary and interstellar matter is in- deed a necessary condition for the transmission of light and other forms of radiance. Now wher- ever a body moves through a material medium, it meets with resistance ; it imparts motion to the medium, and loses motion in so doing. If the body is a planet like Jupiter, weighing a couple of septillions of tons, and rushing along at the rate of eight miles per second through an ether far lighter than the air left in an exhausted receiver, the resistance will be inconceivably small, I admit. Still there will be resistance, and long before the end of time this resistance 306 PLANETARY EVOLUTION will have eaten up all the immense momentum of the planet. A Hindu, wishing to give ex- pression to his idea of the duration of hell-fire, said that if a gauze veil were to be brushed against the Himalaya mountains once in a hun- dred million centuries, the time required for thus wearing away the whole rocky range would measure the tormenfs of the wicked. One mar- vels at such a grandiose imagination ; but the realities of science beggar all such attempts at giving tangible shape to infinitude. The re- sistance of an ethereal medium may work its effects even more slowly than the Hindu's veil, yet in time the effects must surely be wrought. Either the planets are moving in an absolute vacuum — a supposition which is incompatible with the transmission of heat and light — or else the resistance of the medium must tend to diminish their angular velocities.1 In the absence of any counteracting agencies — and, after the cessation of the process above described, none such are assignable — this loss of tangential momentum must ultimately bring all the planets into the sun, one after another, beginning with Mercury and ending with Nep- tune. Here the concentration of matter appears to have reached its limit. But what must now happen ? 1 See Balfour Stewart, in The Conservation of Energy, p. 96. 307 COSMIC PHILOSOPHY Let us note that the tangential momentum lost by the planet is lost only relatively to its distance from the sun. As the planet draws nearer to the sun, its lost tangential momentum is replaced, and somewhat more than replaced, by the added velocity due to the increased grav- itative force exerted by the sun at the shorter distance. But this newly added momentum is all needed to maintain the planet at its new dis- tance from the central mass, and can never be available to carry it back to the old distance. It is thus that Encke's comet moves more and more rapidly as it approaches the sun, into which it appears to be soon destined to be drawn. For these reasons the earth, which now moves at the rate of 18 miles per second, would at- tain a velocity of 379 miles per second when in the immediate neighbourhood of the solar mass. Hence when at last the planet strikes the sun, it must strike it with tremendous force. In a collision of this sort, the heat generated by the earth and sun alone would suffice to pro- duce a temperature of nearly nine million de- grees Fahrenheit. Without pursuing the argu- ment into further detail, it is obvious that the integration of the whole solar system, after tnis fashion, would be followed by the complete disintegration of the matter of which it is con- stituted. After the reunion of the planets with 308 PLANETARY EVOLUTION the sun, the next stage is the dissipation of the whole mass into a nebula. If we now go back for a moment to the be- ginning, and ask what antecedent form of en- ergy could have generated the motion of repul- sion which sustained our genetic nebula at its primitive state of expansion, the reply must be that nothing but a rapid evolution of heat could have generated such a motion of repulsion. And if we ask whence came this rapid evolu- tion of heat, we may now fairly surmise that it was due to some previous collision of cosmical bodies ; arrested molar motion being incompar- ably the most prolific known source of heat. Thus we get a glimpse of some preceding epoch of planetary evolution, from the final catastro- phe of which emerged the state of things which we now witness. We have here reached the very limit of scientific inference. For note that, since the greater part of the potential energy represented by the primitive expansion of our solar nebula has been transformed into heat and radiated away, and is not represented by any form of motor energy now stored up in the solar svs- tem, it follows that the sudden transformation of the penultimate molar motions of the plan- ets into heat cannot result in the production of another nebula so large as the one from which 309 COSMIC PHILOSOPHY our present system has been evolved. In seek- ing to trace out the implications of this conclu- sion, we at once arrive at an impassable barrier, which is only shifted, but not overthrown, when we consider the results of the probable ultimate conflict between our own system, thus disin- tegrated, and other sidereal systems belonging to our galaxy. In order to give a complete account of the matter, we ought to know what has become of all this motor energy which we have been so prodigally pouring away, in the shape of radiant heat, into the interstellar spaces. Is the equivalent of this motor energy ever to be restored, or is the greater part of it forever lost in the abysses of infinite space ? Before we can answer such a question, we need to know whether the interstellar ether, which is the ve- hicle for the transmission of molecular motion, is definitely limited in extent, or practically in- finite ; and we need to take into the account the dynamic relations, not only of our entire galac- tic system, but of other stellar systems, if such there are, beyond the utmost ken of the tele- scope. Here science fails us. Astronomy, the simplest and clearest of the sciences, becomes, when treated on this great scale, the most diffi- cult and obscure. An infinity and an eternity confront us, the secrets of which we may not hope to unravel. At the outermost verge to which scientific methods can guide us, we can 310 PLANETARY EVOLUTION only catch a vague glimpse of a stupendous rhythmical alternation between eras of Evolu- tion and eras of Dissolution, succeeding each other " without vestiges of a beginning and without prospect of an end." 3" CHAPTER VI THE EVOLUTION OF THE EARTH1 IN treating of Evolution in general, it was shown how organic bodies are, by a pecu- liar concurrence of conditions, enabled to lock up a great deal of motion within a small compass, so that permanent redistributions of structure and function can be effected. From the decisiveness with which this peculiar advan- tage possessed by organic bodies was indicated, it might have been surmised that in the case of inorganic aggregates an attempt to trace the secondary phenomena of differentiation and in- tegration would prove illusory,, owing to the absence of this concurrence of conditions. In many inorganic bodies it is true that there does not go on to any notable extent that secondary redistribution which results in increase of hete- rogeneity. The evolution of a cloud, a rock, or a crystal, is little more than an integration of matter attended by dissipation of motion. In the evolution of the solar system, on the other hand, we have witnessed an increase in heterogeneity, definiteness, and coherence that 1 [See Introduction, § 17.] 312 THE EVOLUTION OF THE EARTH is very marked, though by no means so pro- minent as in the case of organic evolution. This increase in determinate multiformity, such as it is, is due to the special mechanical principle that in any rotating system of particles, regarded as practically isolated, a steady concentration, entailing increased rotatory velocity, must end in the segregation of the equatorial zone from the rest of the system. This principle is ex- emplified, on a diminutive scale, in the artificial evolution of a system of oil-globules, whereby M. Plateau has imitated the evolution of the planets. To the resulting equilibration between gravity and the centrifugal tendency, at the place where the detachment occurred, is due the permanence and definiteness of the structural differentiation. Owing to these conditions, and to its enormous size, implying great power of condensation along with the very slow dissipa- tion of the heat generated by the condensation, the integration of our genetic nebula has been compatible with the retention of much relative motion of parts. And here accordingly, as in all cases where there-is a considerable retention of internal motion, the secondary rearrange- ments characteristic of Evolution have been con- spicuously manifested. In the evolution of our earth, regarded by itself, we have also to notice a very decided progress in determinate multiformity, even with- 3l3 COSMIC PHILOSOPHY out taking into the account that specialized group of terrestrial phenomena which we distin- guish as organic. Here there have been two con- ditions favourable to the retention of enough motion to allow considerable secondary rear- rangement of parts. In the first place the great size of the earth has prevented it from parting too rapidly with the heat generated during its condensation ; and since the early formation of a solid, poorly conducting crust, the loss from radiation would seem to have been very grad- ual. The importance of this circumstance may best be appreciated by remembering the very different career of the moon, as indicated in the foregoing chapter. The disappearance of igne- ous and aqueous agencies on the moon implies the cessation of structural rearrangement there at this early date ; * and when we sought for an explanation of this state of things, we found an adequate explanation in the rapid loss of heat which the small size of the moon has entailed. It is not likely, therefore, that the moon can ever have been the theatre of a geologic and organic development so rich and varied as that which the earth has witnessed.2 1 This statement must be taken, however, with some qual- ification. See above, pp. 284, 285. 2 An example of the too hasty kind of inference which is often drawn in discussing the question of life upon other plan- ets may be found in a recent lucid and suggestive pamphlet 3H THE EVOLUTION OF THE EARTH In the second place, the following chapter will show that the chief circumstance which has favoured terrestrial heterogeneity has been the continuous supply of molecular motion from by Professor Winchell, entitled *« The Geology of the Stars." " The zoic age of the moon," says the author, " was reached while yet our world remained, perhaps, in a glowing condition. Its human period was passing while the eozoon was solitary occupant of our primeval ocean. ' ' More careful reflection will probably convince us that, with such a rapid succession of geo- logic epochs, the moon can hardly have had any human period. For the purposes of comparative geology, the earth and the moon may be regarded as of practically the same antiquity. Now, supposing the earliest ape-like men to have made their appearance on the earth, say during the Miocene epoch, we must remember that at that period the moon must have ad- vanced in refrigeration much farther than the earth. Supposing organic evolution to have gone on with equal pace in the two planets, it might be argued that the moon would be fast becom- ing unfit for the support of organic life at about the time when man appeared on the earth. Still more, it is a fair inference from the theory of natural selection, that upon a small planet there is likely to be a slower and less rich and varied evolution of life than upon a large planet. On the whole, therefore, it does not seem likely that the moon can ever have given rise to organisms nearly so high in the scale of life as human beings. Long before it could have attained to any such point, its sur- face is likely to have become uninhabitable by air-breathing organisms. Long before this, no doubt, its surface air and water must have sunk into its interior, and left it the mere lifeless ember that it is. The moon would thus appear to be not merely an extinct world, but a partially aborted world ; and the still smaller asteroids are perhaps totally aborted worlds. Nevertheless, from the earth down to the moon, and from the 3*5 COSMIC PHILOSOPHY the sun. To this source may be traced all the aqueous phenomena, save the tides, which con- cur in maintaining the diversity of the earth's surface. And having thus seen how a complex geologic evolution is rendered possible, we shall further discern that organic evolution also, that highly specialized series of terrestrial events, is rendered possible by the same favouring circum- stance. Let us now proceed to note two or three conspicuous features of geologic evolution, re- membering that in so doing we are but follow- ing out a portion of the phenomena of planetary evolution discussed in the preceding chapter. There is no demarcation in the series of phe- nomena, save that which we arbitrarily introduce for convenience of study and exposition. The process of integration of matter and dissipation of motion which we have just witnessed in the solar nebula as a whole, we have now to witness in that segregated portion of it which we call our earth, and we have to observe how here also indeterminate uniformity has been suc- ceeded by determinate multiformity. moon down to an asteroid, the differences are at bottom only differences of degree ; though the differences in result may range all the way from a world habitable by civilized men down to a mere dead ball of planetary matter. An interesting example, if it be sound, of the continuity of cosmical phe- nomena. 316 THE EVOLUTION OF THE EARTH In the formation of a solid crust about the earth, there appeared the first conspicuous geo- logic differentiation ; resulting not only in in- creased heterogeneity, but in increased definite- ness, as the crust gradually solidified. For not only did the planet thus acquire a more definite figure, but also a more definite movement — since the solidification of the crust must have diminished the oblateness of the spheroid, thus gradually reducing the disturbance known as precession. Next with the deposit of water in the hollow places of this crust, there came the dif- ferentiation between land, sea, and atmosphere ; and this differentiation became more marked as vast quantities of carbonic acid, precipitated in this primeval rain, left the atmosphere purer, and purified also the ocean by segregating its contained lime. At the same time that this vast condensation of ocean-water from preex- isting steam constituted a secondary integration attendant upon the earth's loss of molecular motion, the further thickening of the solid crust began to entail other more local integra- tions. As Mr. Spencer points out, while the earth's crust was still very thin, there could be neither deep oceans nor lofty mountains nor extensive continents.1 Small islands, barren of life, washed by shallow lakes void of animate 1 [See Spencer's First Principles, Part II. chap. xiv. § 109.] 317 COSMIC PHILOSOPHY existence, and covered with a dense atmosphere, loaded with carbonic acid and aqueous vapour, must have characterized the surface of our planet at this primeval epoch. But as the ever thickening crust slowly collapsed about its con- tracting contents, mountain ridges of consider- able height could be gradually formed, islands could cohere over wider and wider spaces, and deeper basins would permit the accumulation of large bodies of water. Numerous integra- tions of islands into continents, and of lakes into oceans, would thus occur, making the dif- ferentiation of land and sea more distinct and definite. The integration of continents and the rise of mountain chains in different directions must have enlarged the areas of denudation, and thus rendered possible the integration of masses of detritus into extensive sedimentary strata. Differences of watershed or of river- drainage thus caused added variety to the re- sulting geologic formations ; and these, crum- bling into soil of more or less richness, afterward impressed differences upon vegetation, and thus indirectly upon animal life. Yet again, the thickening of the crust must have added to the definite heterogeneity of the surface by its effect upon volcanic phenomena. While the crust was still thin, the angry waves of liquid matter imprisoned beneath must have continually burst 3i8 THE EVOLUTION OF THE EARTH through volcanic vents, suddenly vaporizing large quantities of surface-water, and causing phenomena similar to those now witnessed upon Saturn and Jupiter. As the crust thick- ened, these volcanic agencies were more and more restrained: craters became restricted to certain localities where the crust was less thick than elsewhere, and earthquake waves began to run, as at present, along definite lines. Those well - regulated earthquake pulses which raise continents and ocean-floors at the rate of a few inches or feet per century now began to in- crease the definite heterogeneity of the surface. To the long rhythms of elevation and subsi- dence thus produced have been due countless differentiations in the directions of ocean-cur- rents and continent-axes, in watershed, in the composition of sedimentary strata, and in cli- mate. And to all these may be added the met- amorphosis of sedimentary rocks by volcanic heat, and the seismic shoving up of strata at various angles. All these geologic phenomena are thus seen to be classifiable as differentiations and integra- tions of the earth's superficial matter, caused by the continuous integration of the earth's mass with its attendant dissipation of molecular mo- tion. We may. next note that meteorologic phenomena are similarly classifiable. Before the 319 COSMIC PHILOSOPHY solidification of its crust, our planet must have been comparatively homogeneous in tempera- ture, owing to the circulation which is always maintained in masses of heated fluid. The sur- face portions must, however, have been some- what cooler than the interior, and this differ- ence would be rendered more definite by the formation of the crust, and by the subsequent separation of the ocean from the gaseous atmos- phere. As the contour of land and sea became more definite and more permanent, differences in temperature between different parts of the sur- face must likewise have become more decided. Nevertheless the chief cause of climatic differen- tiations — the inclination of the earth's axis — did not begin to produce its most conspicuous effects until a later period. As long as our planet retained a great proportion of its primitive heat, there could have been little difference between winter and summer, or between the temperature at the poles and at the equator. But when the earth had lost so much heat that its external temperature began to depend chiefly upon the supply of solar radiance, then there commenced a gradual differentiation of climates. There be- gan to be a marked difference between summer and winter, and between arctic, temperate, and tropical zones. And now also the distribution of land and sea began to produce climatic ef- fects, owing to the fact that solar radiance is 320 THE EVOLUTION OF THE EARTH both absorbed and given out more rapidly by- land than by water. Areas of the earth's surface where sea predominated began now to be dis- tinguished from areas where land predominated, by their more equable temperature. And be- cause the amount of solar radiance retained de- pends upon the density of the atmosphere, there ensued differences of climate between mountains and valleys, between table-lands and low-lying plains. Here too the increased heterogeneity was attended by increased definiteness and per- manence of climatic relations. For the thermal variations, depending on the earth's rhythmic change of position with reference to the sun, set up atmospheric currents in definite directions and of tolerably regular recurrence. Sundry of these currents, swayed by the earth's rotatory momentum, became specialized as trade-winds and monsoons ; while in the ocean there went on a similar specialization, as exemplified in the constant course of the Gulf Stream and other marine currents. The definiteness of the total result, as well as its heterogeneity, may be well illustrated by any map of isothermal lines, — bearing in mind, as we must, that during long periods these lines shift only within narrow limits. Among the various portions of our earth's surface, moreover, evolution has brought about a climatic interdependence. The dependence of 321 COSMIC PHILOSOPHY terrestrial temperature upon the supply and dis- tribution of solar radiance has entailed a further dependence of local temperatures upon one an- other. For example the warm temperature of southern Europe is largely dependent on the hot dry winds which blow from Sahara, and which powerfully assist in melting the glaciers of the Alps. If Sahara were to be submerged — as indeed it has been at a recent epoch — these dry winds would be replaced by cooler winds charged with vapour, which would condense into snow on the Alps, and thus enlarge the glaciers already formed there, instead of melting them away. Thus the climate would be changed throughout Europe, and the direction of winds would be altered over a still larger area of the globe. If Lapland and the isthmus of Panama were to subside at the same time, so that ice- bergs could float through the Baltic to the coast of Prussia, while the Gulf Stream would be diverted into the Pacific Ocean, the climate of Europe might become glacial. Yet either the submergence of Greenland, or the elevation of the East Indian Archipelago into a continuous continent, would perhaps suffice to neutralize, all these agencies, and restore the genial warmth. In such climatic relations we see vividly illus- trated that kind of integration which brings the condition of each part of an aggregate into de- 311 THE EVOLUTION OF THE EARTH pendence upon the condition of all the other parts.1 It is now sufficiently proved that the devel- opment of the earth, like the development of the planetary system to which it belongs, has been primarily an integration of matter and dissipation of motion, and secondarily a change from indefinite homogeneity with relative isola- tion of parts to definite heterogeneity with rel- ative interdependence among parts. But our survey of telluric evolution is as yet far from complete. While enough has been said con- cerning the redistributions of matter which have gone on over the face of the globe, nothing has been said concerning the far more wonderful and interesting redistributions of the molecular motion which the earth is continually receiving from the sun. Here, as already briefly hinted, we have the chief source of terrestrial heteroge- neity. In the chapter on the Law of Evolution it was observed, as a general truth, that homo- geneous forces incident upon a heterogeneous aggregate undergo differentiation and integra- tion. We shall now find this general truth beau- tifully exemplified in the history of the surface 1 [These meteorological conclusions, current at the time when Fiske wrote, would probably have been a good deal modified had he rewritten this chapter in the light of present opinion. ] 3*3 COSMIC PHILOSOPHY of our planet. At a remote era in that history, the differentiation and integration of solar radi- ance began gradually to constitute the most im- portant part of the complex process of terrestrial evolution. We have now to show how this has been done ; and we shall find it desirable to introduce the subject with an inquiry into the Sources of Terrestrial Energy. 324 CHAPTER VII THE SOURCES OF TERRESTRIAL ENERGY \T the outset we may state broadly that h-\ all terrestrial energy is due either to -*- -*- direct gravitative force, or to the arrest of the centripetal motion produced by gravitative force, either in the earth or in the sun. In other words, the entire series of terrestrial phenomena is the complex product of the earth's internal heat, combined with solar radiance, and with direct gravitative force exercised- by the moon and other planets. Beginning with the smallest and least con- spicuous of these sources of energy, a mere allu- sion will suffice for the effects wrought upon the earth by its companion planets through the medium of their tidal action upon the sun. That the phenomena of the aurora borealis, as well as the periodic variations in the position of the magnetic needle, are dependent upon the solar spots, is now a well-established doctrine ; and it seems not unlikely that we shall erelong suc- ceed in tracing out other dependences of this sort, — as is shown, for example, in Mr. Mel- 325 COSMIC PHILOSOPHY drum's investigation of the relations between sun-spots and rainfall. And whatever may be the final explanation of the phenomena of sun- spots, there can be little doubt that the perio- dicity of these phenomena is conditioned by the positions of the various planets, and especially of the giants Jupiter and Saturn. But these in- terrelations, though they may be much more important than is as yet suspected, need not now detain us. Such further effects as may be wrought upon the earth by polarized light sent from the other planets, and by radiance from remote stellar systems, may be left out of the account. Nor need we do more than allude to the moon's gravitative force as the chief cause of the oceanic tides, with their resultant geolo- gic phenomena. Passing over all these circum- stances, we come to the still unexpended energy represented by the earth's internal heat, con- cerning which we need only say that it is the cause of the geologic phenomena classed as igne- ous. Volcanic eruptions, earthquake shocks, elevations and subsidences of continents and ocean - floors, metamorphoses of sedimentary rocks, boiling springs, fractures of strata, and formations of metallic veins, are the various manifestations of this form of terrestrial energy. But all these grand phenomena must be re- garded as immeasurably inferior in variety and importance to those which are due to the trans- 326 SOURCES OF TERRESTRIAL ENERGY formation of solar radiance. These must be de- scribed with somewhat more of detail. First, with the exception of the changes wrought by the tides, all the geologic phenomena classed as aqueous are manifestations of transformed solar energy. Pulses of molecular motion proceed- ing from the sun are stored as reserved energy in masses of aqueous vapour raised from the sea. This energy is again partly given out as the vapour is condensed into rain and falls to the ground. The portion which remains is expended in the transfer of the fallen water through the soil, till it collects in rivulets, brooks, and rivers, and gradually descends to the ocean whence so- lar radiance raised it, bearing along with it divers solid particles which go to form sedimentary strata. The wind which blew these clouds into the colder regions where they consolidated into raindrops, was set in motion by solar energy, — since all winds are caused by the unequal heating of different parts of the earth's surface. Molar motion stored up in these vast masses of moving air is given out not only in the driv- ing of clouds, but also in the raising of waves on rivers and oceans ; and it is still further ex- pended in the wearing away of shores and in- dentation of coast-lines which these waves effect. All the energy thus manifested by rains and rivers, winds and waves, is transformed solar radiance. And in like manner, if asked whence came the 327 COSMIC PHILOSOPHY molar motion exhibited in the transfer of vast masses of sea-water along definite lines, as in the Gulf Stream and other marine currents, we may safely answer — whatever view we adopt as to the details of these movements — that it was originally due to the heat which so rarefied this water as to make it yield to the pressure of adjacent colder and denser water. And this heat came to the earth in the solar rays. Thus all movements of gaseous, liquid, and solid matter upon the earth's surface, except volcanic and tidal movements, are simply transformations of the heat which is generated by the progressive integration of the sun's mass. But this is not the end of the matter. Our last sentence implicitly included the phenomena of life among those due to solar radiance, since the phenomena of life, whatever else they may be, are certainly included among the complex movements of gaseous, liquid, and solid mat- ters, which occur upon the earth's surface. Let us note some of the various ways in which mo- lecular motion, sent from the sun, is metamor- phosed into vital energy. The seed of a plant, buried in the damp earth, grows by the integration of adjacent nutritive materials, but the energy which effects this union consists in the solar undulations by which the soil is warmed. Diminish, to a certain extent, the daily supply of radiance, as in the long arctic 328 SOURCES OF TERRESTRIAL ENERGY and the short temperate winters, and the seed will refuse to grow. Though nutritive material may be at hand in abundance, there is no molec- ular motion which the seed can absorb. When the seed grows and shoots up its delicate green stalk, tipped with a pair of leaflets, these leaflets begin to absorb and transform those more rapid waves of the sunbeam, known as light and ac- tinism. That the plant may continue to grow, by assimilating carbon and hydrogen, it is ne- cessary for the leaf- molecules to decompose the carbonic acid of the atmosphere, and for the molecules of the rootlets to decompose the water which trickles through the ground. But before this can be done, the molecules of leaf and rootlet must acquire motor energy, — and this is supplied either directly or indirectly by the sunbeam. The slower undulations, pene- trating the soil, set in motion the atoms of the rootlet, and enable them to shake hydrogen- atoms out of equilibrium with the oxygen- atoms which cluster about them in the compound molecules of the water. The swifter undulations are arrested by the leaves, where they commu- nicate their motor energy to the atoms of chlo- rophyll, and thus enable them to dislodge adja- cent atoms of carbon from the carbonic acid in which they are suspended. And these chemi- cal motions, going on at the upper and lower extremities of the plant, disturb the equilibrium 329 COSMIC PHILOSOPHY of its liquid parts, and thus inaugurate a series of rhythmical molar motions, exemplified in the alternately ascending and descending currents of sap. And lastly these molar motions, per- petually replenished from the same external sources, are perpetually expended in the molec- ular integration of vegetable cells and fibres. Thus all the energy stored up in the plant, both that displayed in the chemical activities of leaves and rootlets, and that which is displayed in cir- culation and growth, is made up of transformed sunbeams. The stately trunk, the gnarled roots, the spreading branches, the rustling leaves, the delicately tinted blossoms, and the tender fruit are all — as Moleschott no less truly than poet- ically calls them — the air-woven children of light. In remote geologic ages untold millions of these solar beams were occupied in separating vast quantities of carbon from the dense atmos- phere, and incorporating it in the tissues of in- numerable forests. Charred by slow heat, and gradually petrified, this woody tissue became transformed into coal, which now, dug up from its low-lying beds and burned in stoves and furnaces, is compelled to give up the radiance which* it long ago purloined from the sun. When placed under the engine-boiler, these transformed sunbeams are again metamorphosed into molar motions of expanding vapour, which 330 SOURCES OF TERRESTRIAL ENERGY cause the rhythmic rise and fall of the piston, and drive the running-gear of the machine shop or propel the railway train. In such wise it may be shown that the various agencies which man makes subservient to industrial purposes are nothing but variously differentiated sun- beams. The windmill is driven by atmospheric currents which the sun set in motion. The water-wheel is kept whirling by streams raised by the sun to the heights from which they are rushing down. And the steam-engine derives its energy from modern or from ancient sun- beams, according as its fires are fed by wood or by coal. But the solar energy stored up by vegetables is given out not only in such mechanical pro- cesses, but also in the vital activities of the hu- man beings whose needs such processes supply. The absolute dependence of animal upon vegetal life is illustrated in the familiar fact that animals cannot directly assimilate inorganic compounds. The inorganic water which we drink is necessary to the maintenance of life ; but it percolates untransformed through the tissues and blood- vessels, and it quits the organism in the same chemical condition in which it entered it. And although minute quantities of the salt which we daily eat, and of the carbonates and iodides of iron which we sometimes take as tonics, may perhaps undergo transformation in the tissues, 331 COSMIC PHILOSOPHY it is none the less true that the substance of our tissues can only be repaired by means of the complex albuminous molecules which solar energy originally built up into the tissues of vegetables. Herbivorous animals in each of the great classes feed directly upon vegetable, fibre, and so rearrange its molecules that the re- sultant tissues are more highly nitrogenous than those from which they were formed. More active carnivorous animals derive from the enormous chemism latent in these nitrogenous fabrics the vital energy displayed in their rapid bounds and in their formidable grip. But the energies which imprisoned this tremendous chemical force in the complex molecules which the animal assimilates were at first supplied by sunbeams. Metamorphosed originally into the static energy of vegetable tissue, this sun-derived power is again metamorphosed into the dyna- mic energy which maintains the growth of the animal organism. And from the same prime- val source comes the surplus energy which, after the demands of growth or repair have been satisfied, is expended in running, jumping, fly- ing, swimming, or climbing, as well as in fight- ing with enemies and in seizing and devouring prey. Besides these indirect and doubly indirect methods in which animals differentiate solar energy, there are ways in which the metamor- 33* SOURCES OF TERRESTRIAL ENERGY phosis is directly effected. To cite Dr. Carpen- ter's conclusions, as epitomized by Mr. Spen- cer : " The transformation of the unorganized contents of an egg into the organized chick is altogether a question of heat : withhold heat and the process does not commence ; supply heat and it goes on while the temperature is maintained, but ceases when the egg is allowed to cool. ... In the metamorphoses of insects we may discern parallel facts. Experiments show not only that the hatching of their eggs is determined by temperature, but also that the evolution of the pupa into the imago is simi- larly determined, and may be immensely ac- celerated or retarded according as heat is arti- ficially supplied or withheld." The phenomena thus briefly cited are to be classed under the general head of organic stimulus — and in a wide sense, one might almost say that all stim- ulus is the absorption of vital energy which was originally solar. Sunlight stimulates ani- mals indirectly, as in the case of actiniae which are made more vivacious when neighbouring sea-weed, smitten by sunbeams, pours oxygen into the water in which they move ; and also in the case of hard-worked men who gain vigour from the judicious use of vegetable nar- cotics. The waves of motor energy which the human organism absorbs in whiffs of tobacco- smoke are but a series of pulsations of trans- 333 COSMIC PHILOSOPHY formed sunlight.1 But animals are also directly stimulated by the solar rays, as in the cases of insects which begin to fly and crawl in early summer, and of hibernating mammals which emerge from their retreats at the approach of warm weather. By its stimulating effect on the retina, and thence on the medulla oblongata, sunlight quickens the breathing and circulation in higher animals, and thus facilitates the repair of tissue. In the night we exhale less carbonic acid than in the daytime. Again, the stunted growth and pale sickly faces of men and women who live in coal-mines, or in narrow streets and dark cellars, are symptoms traceable to anaemia, or to a deficiency of red globules in the blood. Whence it seems not improbable that the for- mation of red globules, like the formation of sap in plants, may be in some way directly assisted by solar undulations. Mysteriously allied with the vital phenomena of nutrition, innervation, and muscular action are the psychical phenomena of feeling and thought. Though (as previously hinted and as I shall hereafter endeavour to prove) the gulf 1 As the poet-philosopher Redi says of wine : — M Si bel sangue e un raggio acceso Di quel Sol che in ciel vedete j E rimase avvinto e preso Di piu grappoli alia rete." Bacco in Toscana ; Opere, torn. i. p. 2. 334 SOURCES OF TERRESTRIAL ENERGY between the phenomena of consciousness and all other phenomena is an impassable gulf, which no future extension of scientific know- ledge is likely to bridge over, it is nevertheless unquestionable both that every change in con- sciousness is conditioned by a chemical change in ganglionic tissue, and also that there is a discernible quantitative correspondence between the two parallel changes. Let us glance for a moment at certain facts which will serve to illustrate and justify these propositions.1 Those changes of consciousness which are va- riously classified as thoughts, feelings, sensa- tions, and emotions cannot for a moment go on save in the presence of certain assignable physical conditions. The. first of these conditions is complete con- tinuity of molecular cohesion among the parts of nerve-tissue. A nerve which is cut does not transmit sensori-motor impulses ; and even where the continuity of molecular equilibrium is disturbed, without overcoming cohesion, as in a tied nerve, there is no transmission. It is in the same way that pressure on the cerebrum instantly arrests consciousness when a piece of the skull is driven in by a blow, and slowly arrests it when coma is produced by congestion 1 [See, regarding the immediately subsequent portion of the text, Introduction, § 1 7, where the contrast between Spencer and Fiske, as to the topic here in question, is pointed out.] 335 COSMIC PHILOSOPHY of the cerebral arteries. Now the need for com- plete continuity of molecular equilibrium, both in the white and in the gray tissue, is a fact of no meaning unless a molecular rearrangement is an indispensable accompaniment of each change in consciousness. Secondly j the presence of a certain amount of nutritive material in the cerebral blood-vessels is essential to every change in consciousness ; and upon the quantity of material present de- pends, within certain limits, the rapidity of the changes. While rapid loss of blood causes faint- ing, or total stoppage of conscious changes, it is also true that lowered nutrition, implying defi- ciency of blood, retards the rate and interferes with the complication of mental processes. In a state of extreme anaemia not only does think- ing go on slowly, but the manifold compound- ing and recompounding of conscious changes, which is implied in elaborate quantitative rea- soning, cannot go on at all. Now the need for the constant presence of nutritive material is a meaningless fact unless each change in consciousness is dependent upon a molecular transfer between the nutritive material and the nerve-substance. Thirdly, the maintenance of conscious changes requires the presence of certain particular ma- terials in the blood, and the absence, in any save the smallest proportions, of certain other 336 SOURCES OF TERRESTRIAL ENERGY materials ; while there are yet other materials upon the presence of which the rate and com- plication of conscious changes largely depend. The familiar fact that consciousness cannot for an instant continue unless oxygen is in contact with the gray tissue of the cerebrum is alone sufficient to prove that no conscious change is possible, save as the accompaniment of a chemi- cal change. On the other hand, the presence of carbonic acid or of urea in considerable quanti- ties retards the rate and prevents the elaboration of thinking ; and in still larger quantities it puts an end to consciousness. And in similar wise the effects of alcohol, opium, and hemp, as well as of that Siberian fungus whose inhaled va- pour makes a straw in the pathway look too large to be jumped over, show us most vividly how immediate is the dependence of complex mental operations upon chemical changes. Fourthly, the fact that the vigour and com- plexity of mental manifestations bear a marked ratio to the weight of the brain, to the amount of phosphorus contained in its tissue, and to the number and intricacy of the fine sinuous creases in the gray surface of the hemispheres, shows plainly that changes in consciousness are conditioned both by the amount and by the arrangement of nerve-material. Fifthly, we may see a like significance in the facts that the amount of alkaline phosphates vou n 337 COSMIC PHILOSOPHY excreted by the kidneys varies with the amount of mental exertion ; and that emotional excite- ment so alters the composition of the blood that infants have been poisoned by milk se- creted by their frightened or angry mothers. And lastly may be cited the beautiful experi- ments of Professor Lombard, in which the heat evolved by the cerebrum during the act of thinking was not only detected but measured, and found to vary according to the amount of mental activity going on. These, though the most conspicuous, are but a few among the facts which force upon the physiologist the conclusion that there is no such thing as a change in consciousness which has not for its correlative a chemical change in ner- vous tissue. Hence we may the better under- stand the significance of familiar facts which point to a quantitative correlation between cer- tain states of consciousness and the outward phe- nomena which give rise to them. A bright light, as measured by the photometer, produces a more vivid state of consciousness than a dim light. Substances which the thermometer de- clares to be hot are, under normal circum- stances, mentally recognized as being hot. The consciousness of a sound varies in vividness with the violence of the concussions to which the sound is due. And bodies which are heavy in the balance excite in us correlative sensations of 33* SOURCES OF TERRESTRIAL ENERGY strain when we attempt to move them. Con- versely the molar motions by which our states of feeling are revealed externally, have an en- ergy proportional to the intensity of the feeling ; witness the undulations indicative of pain, which, beginning with a slight twitching of the facial muscles, may end in spasmodic convulsions of the whole body. And of like import is the fact that gentle emotions, like slight electric and nar- cotic stimuli, agreeably quicken the heart's con- tractions ; while violent emotions, suddenly awakened, may stop its beating as effectually as a stroke of lightning or a dose of concentrated prussic acid. The bearings of such facts as these upon our theories of mental phenomena will be duly con- sidered in future chapters. At present we have only to regard them as furnishing conclusive evi- dence that the phenomena which are subjec- tively known as changes in consciousness are objectively correlated with molecular motions of nerve-matter which are seen, in an ultimate analysis, to be highly differentiated forms of solar radiance. Waves of this radiance, speed- ing earthward from the sun at the rate of more than five hundred trillions per second, impart their motor energy to the atoms which vibrate in unison in the compound molecules of the growing grass. Cattle, browsing on this grass, and integrating portions of it with their tissues, 339 COSMIC PHILOSOPHY rearrange its molecules in more complex clus- ters, in which the tremendous chemical energy of heat-saturated nitrogen is held in equilibrium by the aid of these metamorphosed sunbeams. Man, assimilating the nitrogenous tissues of the cow, builds up these clusters of molecules, with their stores of sun-given and sun-restrained en- ergy, into the wondrously complex elements of white and gray nerve-tissue, which, inces- santly liberating energy in decomposition, mys- teriously enable him to trace and describe a portion of the astonishing metamorphosis. When one takes a country ramble on a plea- sant summer's day, one may fitly ponder upon the wondrous significance of this law of the transformation of energy. It is wondrous to re- flect that all the energy stored up in the timbers of the fences and farmhouses which we pass, as well as in the grindstone and the axe lying be- side it, and in the iron axles and heavy tires of the cart which stands tipped by the roadside ; all the energy from moment to moment given out by the roaring cascade and the busy wheel that rumbles at its foot, by the undulating stalks of corn in the field and the swaying branches in the forest beyond, by the birds that sing in the treetops and the butterflies to which they anon give chase, by the cow standing in the brook and the water which bathes her lazy feet, by the sportsmen who pass shouting in the distance as 340 SOURCES OF TERRESTRIAL ENERGY well as by their dogs and guns, — that all this multiform energy is nothing but metamor- phosed solar radiance, and that all these various objects, giving life and cheerfulness to the land- scape, have been built up into their cognizable forms by the agency of sunbeams such as those by which the scene is now rendered visible. We may well declare, with Professor Tyndall, that the grandest conceptions of Dante and JMilton are dwarfed in comparison with the truths which science discloses. But it seems to me that we may go farther than this, and say that we have here reached something deeper than poetry. In the sense of illimitable vastness with which we are oppressed and saddened as we strive to fol- low out in thought the eternal metamorphosis, we may recognize the modern phase of the feel- ing which led the ancient to fall upon his knees and adore — after his own crude, symbolic fashion — the invisible Power whereof the infi- nite web of phenomena is but the visible gar- ment. 341 CHAPTER VIII THE BEGINNINGS OF LIFE1 A MID the chaos of ideas concerning vital /-\ phenomena which prevailed until quite *- ■* recent times, it was hardly strange that organisms, even of a high order of complex- ity, should have been supposed to be now and then directly evolved from lifeless matter, under favourable circumstances. Every reader of an- cient literature will remember how Aristaeus succeeded in replacing his lost swarm of bees ; and the sanction thus accorded by so erudite a poet as Virgil to the popular belief in the gen- eration of insects from putrescent meat is good evidence that the impossibility of such an oc- currence had not yet been suspected, or at least had never been duly appreciated. Still more im- portant is the testimony of Lucretius — who, as Professor Huxley well says, " had drunk deeper of the scientific spirit than any other poet of ancient or modern times except Goethe " — when he alludes to the primordial generation of plants and animals by the universal mother, Earth. It is, however, straining words some- 1 [See Introduction, § 18.] 342 THE BEGINNINGS OF LIFE what beyond their usual meanings to call such speculations " scientific." They were the pro- duct of an almost total absence of such know- ledge as is now called scientific. It was possible to infer that such highly organized creatures as hymenopterous insects, suddenly appearing in putrescent meat, were spontaneously generated there, only because so little was definitely known about the relations of organisms to one another and to the inorganic world. Accordingly, with the very beginnings of modern biological know- ledge, and with the somewhat more cautious and systematic employment of induction character- istic of the seventeenth century, the old belief in spontaneous generation was called in ques- tion. By a series of very simple but apt experi- ments, in which pieces of decaying meat were protected from maggots by a gauze covering, the illustrious Redi proved, to the satisfaction of every one, that the maggots are not produced from the substance of the meat, but from eggs deposited therein by flies. So conclusive were these experiments that the belief in spontaneous generation, which had hitherto rested chiefly upon phenomena of this sort, was almost uni- versally abandoned, and the doctrine that every living thing comes from some living thing — omne vivum ex vivo — received that general ac- ceptance which it was destined to retain down to the present time. With the progress of bio- 343 COSMIC PHILOSOPHY logical knowledge, — as the complex structures and regular modes of growth of the lower ani- mals began to be better understood, and as the microscope began to disclose the existence of countless forms of life infinitesimal in size but complicated in organization, many of which were proved to be propagated either by fission or by some kind of germination, — the doctrine omne vivum ex vivo became more and more impli- citly regarded as a prime article of faith, and the hypothesis of spontaneous generation was not merely scouted as absurd, but neglected as un- worthy of notice. Philosophical theories conspired with obser- vation and experiment to bring about this re- sult. The doctrine omne vivum ex vivo con- sorted well with the metaphysical hypothesis of an archaws, or " vital principle," by means of which Stahl and Paracelsus sought to explain the dynamic phenomena manifested by living organisms. In those days when it was the fash- ion to explain every mysterious group of phe- nomena by imagining some entity behind it, the activities displayed by living bodies were thought to be explained when they were called the workings of a " vital principle " inherent in the living body, but distinct from it and sur- viving unchanged amid its manifold alterations. If a stone falls to the ground, that is a manifes- tation of gravitative force ; but if a stream of 344 THE BEGINNINGS OF LIFE blood comes rushing through a capillary tube, and certain compound molecules of albuminous matter are taken from it and retained by the adjacent tissue, then, according to the vitalistic theory, the " vital principle " is at work. Dur- ing life this " principle " continues to work ; but at death it leaves the organism, which is then given up to the mercy of physical forces. Such was the theory of life which was held by many physiologists even at a time within the recollection of persons now living ; and it doubt- less still survives in minds uninstructed in mod- ern science. So long as this doctrine held un- disputed sway, the belief that all life proceeds from life was not likely to be seriously im- pugned. For whence, save by derivation from some other " principle " like unto itself, could this mysterious " vital principle " arise ? Be- sides all this, the Doctrine of Evolution had not yet been originated ; all things were sup- posed to have been created at once in their present condition ; and, as no need was felt of explaining scientifically the origin of the highest organisms, so there was no disposition to in- quire into the origin of those lowest in the scale. A series of separate creative acts was supposed to account for the whole. Strengthened by these metaphysical concep- tions, the doctrine omne vivum ex vivo remained in possession of the field for two centuries. 345 COSMIC PHILOSOPHY Phenomena apparently at variance with it — such as the occasional discovery of animalcules in closed vessels — were disposed of by the hypothesis, devised by Spallanzani, that the atmosphere is full of invisible germs which can penetrate through the smallest crevices. This hypothesis is currently known as "pansperma- tism," or the " theory of omnipresent germs," or (less cumbrously) as the " germ-theory." Now, as concerns the germ-theory, to which appeal is unhesitatingly made whenever the question of spontaneous generation is discussed, it must be admitted to be extremely plausible ; yet we must not forget that it has never been actually demonstrated : it has not been proved that the germ-theory can do all that its advo- cates require it to do. It may well be the case that the air is everywhere full of germs, too small to be seen, which are capable of giving rise to all the organisms of which there is any question in the controversy about spontaneous generation ; nevertheless this has not been rig- orously demonstrated. The beautiful researches of Professor Tyndall have indeed proved that the atmosphere is everywhere filled with solid particles, in the absence of which it would not be luminous ; and it is fair to suppose that among these particles there are always to be found some which are the germs of monads and bac- teria. Still this can hardly be taken for granted ; 346 THE BEGINNINGS OF LIFE and Dr. Bastian is right in reminding us that it is reasoning in a circle to assume the presence of germs that cannot be detected, merely be- cause there is no other way of accounting for the presence of monads and bacteria in accord- ance with the doctrine of Redi. For in all discussions concerning spontane- ous generation, it should be borne in mind that the doctrine omne vivum ex vivo is itself on trial for its life, and cannot be summoned to the wit- ness box. The very point to be ascertained is whether this doctrine, which is admitted to hold good in the case of all save the lowest forms of life, holds good also of these. The doctrine rests entirely upon induction ; and while, in many cases, it is legitimate to infer a universal propo- sition from a limited induction of instances, it is not legitimate to do so in the present case. For the fact that innumerable highly specialized types of animal and vegetal life are kept up solely by generation ex vivo can in nowise prove that other living things, which are nearly or quite destitute of specialization, may not have their ranks recruited by a fresh evolution from not-living materials. Along with the absence of specialized structure, it may turn out that there is an absence of other characteristics once sup- posed to be common to all living things. This will be more clearly understood as we proceed to consider the change which the last 347 COSMIC PHILOSOPHY half-century has wrought in the theories of life with which Redi's doctrine has hitherto been implicated. The hypothesis of a " vital prin- ciple " is now as completely discarded as the hypothesis of phlogiston in chemistry, or as the Ptolemaic theory in astronomy : no biologist with a reputation to lose would for a moment think of defending it. The great discoveries concerning the sources of terrestrial energy, illus- trated in the foregoing chapter, have made it henceforth impossible for us to regard the dy- namic phenomena manifested by living bodies otherwise than as resulting from the manifold compounding of the molecular forces with which their ultimate chemical constituents are endowed. Henceforth the difference between a living and a not-living body is seen to be a difference of degree, not of kind, — a difference dependent solely on the far greater molecular complexity of the former. As water has properties that belong not to the gases which compose it, so protoplasm has properties that do not belong to the inferior compounds of which it is made up. The crystal of quartz has a shape which is the resultant of the mutual attractions and re- pulsions of its molecules ; and the dog has a shape which is ultimately to be explained in the same way, save that in this case the process has been immeasurably more complex and indirect. Such, in brief, is the theory by which the vital* 348 THE BEGINNINGS OF LIFE istic doctrine of Stahl has been replaced. In- stead of a difference in kind between life and not-life, we get only a difference of degree ; so that it again becomes credible that, under favour- ing circumstances, not-life may become life. In the next place the overthrow of the dogma of fixity of species, and the consequent general displacement of the Doctrine of Creation by the Doctrine of Evolution, have made the scientific world familiar with the conception of the de- velopment of the more specialized forms of life from less specialized forms ; and thus the de- velopment of the least specialized forms of life from the most complex forms of not-life ceases to seem absurd, and even acquires a sort of pro- bability. And finally, the researches of geolo- gists, showing that our earth's surface was once " melted with fervent heat," and confirming the theory of the nebular origin of our planet, have rendered it indisputable that there must once have been a time when there was no life upon the earth ; so that certainly at some time or other, though doubtless not by a single step but by a number of steps, the transition from not- life to life must have been made. Hence the doctrine omne vivum ex vivo, as now held, means neither more nor less than that every assem- blage of organic phenomena must have had as its immediate antecedent some other assemblage of phenomena capable of giving rise to it ; in 349 COSMIC PHILOSOPHY other words, the doctrine has become little more than a specialized corollary from the persistence of force. In the case of all save the lowest or- ganisms, the only antecedent phenomenon capa- ble of giving rise to the organism in question has been inductively proved to be some other organism. But in the case of the lowest organ- isms it is theoretically possible that the requi- site antecedent may in some instances be an assemblage of unorganized materials; and it re- mains for induction to show whether this pos- sibility is ever actually realized or not under existing terrestrial conditions. Such being the modification which modern discoveries have imposed upon the doctrine omne vivum ex vivo, it need hardly be added that the hypothesis of spontaneous generation has undergone a no less important change. The theory that an organism which is to any extent specialized in structure can arise directly from a union of unorganized elements is ruled out of court. Such a conception, though it might be harmonized with the hypothesis of special cre- ations, is utterly condemned by the Doctrine of Evolution. So long as it was possible to believe that enormously complex birds and mammals were somehow conjured into existence, like Aladdin's palace, in a single night, by a kind of enchantment which philosophers sought to dignify by calling it " creative fiat," it might 350 THE BEGINNINGS OF LIFE well have seemed possible for animalcules to be spontaneously generated in air-tight flasks, or even for maggots to arise de novo in decaying meat. Such a view might have been logically defensible, though it was not the one which actually prevailed. But now, in face of the proved fact that thousands of years are required to ef- fect any considerable modification in the specific structures of plants and animals, it has become impossible to admit that such specific structures can have been acquired in a moment, or other- wise than by the slow accumulation of minute peculiarities. Hence " spontaneous generation " can be theoretically admitted only in the case of living things whose grade of composition is so low that their mode of formation from a liquid solution may be regarded as strictly analogous to that of crystals. And when the case is thus stated, it becomes obvious that the phrase "spon- taneous generation " is antiquated, inaccurate, and misleading. It describes well enough the crude hypothesis that insects might be gener- ated in putrefying substances without any as- signable cause ; but it is not applicable to the hypothesis that specks of living protoplasm may be, as it were, precipitated from a solution con- taining the not-living ingredients of protoplasm. If such an origination of life can be proved, none will maintain that it is " spontaneous," since all will regard as the assignable cause the 3Si COSMIC PHILOSOPHY chemical affinity exerted between the enormously- complex molecules which go to make up the protoplasm. No one speaks of " spontaneous crystallization ; " and the ideas suggested by the use of the word " spontaneous " are such as to detract seriously from its availableness as a sci- entific term. We need a phrase which shall simply describe a fact, without any admixture of hypothesis ; and we may cordially recommend as such a phrase Dr. Bastian's archebiosis^ which, without violence to etymology, may be said to mean " life in its beginning," — or, more freely, " beginning of life." % With these preliminaries, the precise question now at issue between the believers in " spon- taneous generation " and their opponents may be stated as follows : Can archebiosis be made to occur at the present day by artificial means ? Or, to be still more accurate, Has archebiosis actually been made to occur at the present day by artificial means ? Is it possible for the experi- menter, without. any assistance from life already existing, to obtain living things merely by bringing together the chemical constituents of protoplasm under suitable physical conditions ? Or, granting the possibility, can it be proved that living things have actually been thus ob- tained ? To this twofold question there are re- turned diverse answers. On the one hand, Dr. Bastian maintains that himself and other experi- 3S* THE BEGINNINGS OF LIFE menters have actually seen archebiosis artificially- brought about. On the other hand, it is likely to be maintained by most competent critics that, while there may be no good reason for denying the possibility of such a triumph of experiment, we have not yet sufficient proof that it has been really achieved. It should not be forgotten that the decision of the more general question of the origin of life on the earth's surface does not depend upon the way in which this special controversy is decided. While it is true that the success of experiments like those of Dr. Bastian would furnish conclusive inductive proof of archebi- osis, it is also true that their complete failure can in nowise be cited in evidence against the doc- trine. On the one hand, the artificial produc- tion of living things, by giving us ocular testi- mony to the beginnings of life, would no doubt enlighten us considerably as to the physical and chemical conditions under which life originates ; and it is therefore highly desirable that ex- perimenters should be able to construct living protoplasm in the laboratory, just as it was de- sirable a few years ago that chemists should be able to produce such organic compounds as alcohol, sugar, and urea, — substances which until lately were thought to be, for some mys- terious reason, inaccessible to human art, but which are now constructed with ease. But on TOL. II 3 S3 COSMIC PHILOSOPHY the other hand, even the demonstrated impos- sibility of producing living things artificially would not weigh a grain in the scale against the doctrine that archebiosis may now occur, and must at some time have occurred, in the great laboratory of nature. That an evolution of or- ganic existence from inorganic existence must at some time have taken place is rendered cer- tain by the fact that there was once a time when no life existed upon the earth's surface. That such evolution may even now regularly take place, among such living things, for instance, as the Bathybius of Haeckel — a sort of albu- minous jelly growing in irregular patches on the sea-bottom — is perhaps not impossible. But that such evolution has been known to take place in air-tight flasks containing decoc- tions of hay, and has moreover resulted in the formation of organisms like vibrios and fungus- spores, is quite another proposition, which the assertor of archebiosis is in no way bound to maintain, and with the fate of which he need not feel himself vitally concerned. The question of " spontaneous generation," then, is but a part, and not the most essential part, of the question as to the origin of life ; and we need not be surprised at finding among Dr. Bastian's opponents such an avowed evolu- tionist as Professor Huxley. Practically, more- over, the question at issue between the advo- 354 THE BEGINNINGS OF LIFE cates of " spontaneous generation " and their antagonists is even narrower than appears from the above statement of it. As practically con- ducted, the dispute is confined to the ques- tion whether certain particular low forms of life — known as vibrios, bacteria, torulae, and mo- nads — which appear in putrescence or in fer- mentation, are produced by archebiosis, or are propagated from germs conveyed in the atmos- phere. If Dr. Bastian's position with reference to this question is destined to become substanti- ated, his work may perhaps mark an epoch in biology hardly less important than that which was inaugurated by Mr. Darwin's " Origin of Species." Unfortunately, the kind of proof which is needed for Dr. Bastian's main thesis is much more difficult, both to obtain and to estimate properly, than the kind of proof by which the theory of natural selection has been substantiated. In the latter case what was needed was some principle of interpretation which should account for the facts of the clas- sification, embryology, morphology, and distri- bution of plants and animals without appealing to any other agencies than such as can be proved to be actually in operation ; and it is because the theory of natural selection furnishes such a principle of interpretation that it has met with such ready acceptance from the sci- 355 COSMIC PHILOSOPHY entific world.1 On the other hand, the fate of the theory of archebiosis, in the shape in which it is held by Dr. Bastian, depends upon the issue of a series of experiments of extra- ordinary delicacy and difficulty, — experiments which are of value only when performed by scientific experts of consummate training, and which the soundest critic of inductive methods must find it perilous to interpret with confi- dence, unless he has had something of the train- ing of an expert himself. For however easy it may seem to the uninitiated to shut up an organizable solution so securely that organic germs from the atmosphere cannot even be imagined capable of gaining access to it, this is really one of the most arduous tasks which an experimenter has ever had set before him. Yet to such rigour of exclusion is the inquirer forced who aims at settling the question by the direct application of the Method of Difference. And thus the question at issue is reduced to that unpromising state in which both parties to the dispute are called upon to perform the appar- ently hopeless task of proving a negative. When living things appear in the isolated solution, the adherents of the germ-theory are always able to point out some imaginable way in which germs might have got in. On the other hand, when 1 I am here anticipating the argument of the two following chapters. 3S& THE BEGINNINGS OF LIFE the panspermatists adduce instances in which no living things have been found, the believers in archebiosis are able to maintain that the failure was due, not to the complete exclusion of germs from without, but to the exclusion of some other physical condition essential to the evolution of living matter. And from this closed circle of rebutting arguments there seem at present to be no means of egress. But in so far as the interpretation of Dr. Bastian's experiments is intended to throw light upon the beginnings of life on the earth, there is a manifest anomaly in the use of such liquid menstrua as the infusions of hay, turnip, beef, or urine, which Dr. Bastian ordinarily employs. Whatever archebiosis may occur in such media can hardly be like the process by which living things first came into existence, since the exist- ence of the beef or turnip implies the previous existence of organisms high in the scale. The positive detection of archebiosis in these and similar menstrua will, of course, have an inter- est of its own ; but, as Mr. Spencer well says, " a tenable hypothesis respecting the origin of organic life must be reached by some other clew than that furnished by experiments on decoction of hay and extract of beef." To meet this objection Dr. Bastian has in some exper- iments used only inorganic substances, like phosphate of soda, and the oxalate, tartrate, or 357 COSMIC PHILOSOPHY carbonate of ammonia, in which the elements essential to the formation of protoplasm are present. Yet in such menstrua as these he be- lieves that he has found even fungus-spores " spontaneously " generated. The contrast here vividly brought before us draws attention to what would seem to be one of the weakest points in Dr. Bastian's theory. It is a long way from tartrate of ammonia and phosphate of soda to the spores of a fungus. It seems too long a way to be traversed in a few days or weeks amid merely the simple conditions which exist within a closed flask. A fungus-spore is not mere shapeless proto- plasm. In it, as in the bacterium and the vibrio, there is a visible specialization of struc- ture, albeit a slight specialization. These infu- soria are " lowest organisms," no doubt ; still they are really organisms and not merely masses of organic matter. They have forms which are more or less persistent ; and in this fact is to be seen the strongest of the objections which may be urged a priori against Dr. Bastian's views. For organic form is a circumstance into which heredity largely enters ; and where we find organisms even so simple as the jointed rods which are called vibrios, it is difficult, on theoretical grounds, not to accredit them with a regular organic parentage. Such considera- tions cannot weigh against a crucial experi- 3J» THE BEGINNINGS OF LIFE ment ; but in the present state of the question they are entitled to serious attention. Dr. Bas- tian argues, with great ingenuity, that just as crystals, growing in a liquid menstruum, take on shapes that are determined by the mutual attractions and repulsions of their molecules, so do these colloidal bodies, which we call monads and bacteria, arising by " spontaneous genera- tion " in liquid menstrua, take on forms that are similarly determined. The analogy, how- ever, is not exact. I am not disposed to deny that the shape of a bacterium, or indeed of a wasp, a fish, a dog, or a man, is due, quite as much as the shape of a crystal of snow or quartz, to the forces mutually exerted on each other by its constituent molecules. But it must be re- membered that in the case of an organism the direction of these forces depends, in a way not yet explained, upon the directions in which they have been exerted by ancestral organisms. In other words, a set of definite tendencies has been acquired during the slow evolution of organic life ; and it may well be doubted that, even in the case of the bacterium, a tendency toward the formation of single or double nuclei can have been gained during the evolution of a single generation of individuals. For in colloidal mat- ter, as such, there is no definite tendency to- ward the formation of nuclear spots, such as are seen in bacteria. It is a main characteristic of 359 COSMIC PHILOSOPHY colloids, as contrasted with crystalloids, not to have any specific form. It is therefore hard to believe that, during the decomposition of some saline liquid, the freed elements not only recombine into a colloid, but even go so far as to take on the specific shape of a bacterium or vibrio. When any such succession of pheno- mena appears to occur, it clearly points to the ill-understood but imperative fact of heredity through a long past. Until this difficulty is either cleared away by trustworthy deduction, or overridden by some crucial experiment, I do not think that the ad- vocates of " spontaneous generation " can be said to have made out their case ; and such an abstruse question is here opened that it is not likely soon to be settled. For the present, in representing to ourselves how life may have originated upon the earth, we are reduced to a few most general considera- tions. However the question may eventually be decided as to the possibility of archebiosis occurring at the present day amid the artificial circumstances of the laboratory, it cannot be denied that archebiosis, or the origination of living matter in accordance with natural laws, must have occurred at some epoch in the past. That life has hot always existed upon the earth's surface is certain ; and the following considera- tions will show that in its first appearance there 360 THE BEGINNINGS OF LIFE need not have been anything either sudden or abnormal. When our earth, refusing to follow in their retreat the heavier portions of the solar nebula, began its independent career as a planet, its surface was by no means so heterogeneous as at present. We may fairly suppose that the tem- perature of that surface cannot have been lower than the temperature of the solar surface at the present time, which is estimated at three mil- lion degrees Fahrenheit, or some fourteen thou- sand times hotter than boiling water. At such a temperature there could have been no forma- tion of chemical compounds, so that the chief source of terrestrial heterogeneity did not ex- ist ; while physical causes of heterogeneity were equally kept in abeyance by the maintenance of all things in a gaseous state. We have now to note how the mere consolidation and cooling of this originally gaseous planet must have given rise to the endless variety of structures, organic as well as inorganic, which the earth's surface now presents. The origination of life will thus appear in its proper place, as an event in the chemical history of the earth. Let us see what must have been the inevitable chemi- cal consequences of the earth's cooling. In a large number of cases heat is favourable to chemical union, as in the familiar instance of lighting a candle, a gas jet, or a wood fire. 361 COSMIC PHILOSOPHY The molecules of carbon and oxygen, which will not unite when simply brought into juxta- position, nevertheless begin rapidly to unite as soon as their rates of undulation are heightened by the intense heat of the match. In like man- ner the phosphoric compound with which the end of the match is equipped refuses to take up molecules of atmospheric oxygen until its own molecules receive an increment of motion supplied by the arrested molar motion of the match along a rough surface. So oxygen and hydrogen do not combine when they are simply mingled together in the same vessel ; but when sufficiently heated they explode and unite to form steam. In these, and in many other cases, a certain amount of heat causes substances to enter into chemical union. But it is none the less true that an enormous supply of heat im- plies such violent molecular undulation as to render chemical union impossible. Since the mode of attractive force known as chemism acts only at infinitesimal distances, the increase of thermal undulation, which at first only causes such a molecular rearrangement as to allow mu- tually attracting molecules to rush together, must at last cause such a separation of particles that chemism will be unable to act. This infer- ence from known laws of heat is fully verified by experiment in the case of all those com- pounds which we can decompose by such ther- 362 THE BEGINNINGS OF LIFE mal means as we have at command. Speaking generally, the most complex compounds are the most unstable, and these are the soonest decom- posed by heat. The highly complex organic molecules of fibrine and albumen are often separated by the ordinary heat of a summer's day, as is witnessed in the spoiling of meat. Supersalts and double salts are decomposed at lower temperatures than simple salts ; and these again yield to a less amount of heat than is re- quired to sunder the elements of deutoxides, peroxides, etc. The protoxides, which are only one degree more complex than simple elements, withstand a still higher temperature, and sev- eral of them refuse to yield to the greatest heat which we can produce artificially. No chemist, however, doubts that a still greater heat would decompose even these. We may thus picture to ourselves the earth's surface as at the outset composed only of un- combined elements, of free oxygen, hydrogen, nitrogen, carbon, sulphur, etc., and of iron, copper, sodium, and other metals in a state of vapour. With the lowering of this primitive temperature by radiation, chemical combinations of greater and greater heterogeneity became gradually possible. First appeared the stable binary compounds, such as water and the in- organic acids and bases. After still further low- ering of temperature, some of the less stable 3*3 COSMIC PHILOSOPHY compounds, such as salts and double salts, were enabled to appear on the scene. At a later date came the still more heterogeneous and un- stable organic acids and ethers. And all this chemical evolution must have taken place be- fore the first appearance of living protoplasm. Upon these statements we may rest with confi- dence, since they are immediate corollaries from known properties of matter. When it is asked, then, in what way were brought about the various chemical combina- tions from which have resulted the innumera- ble mineral forms which make up the crust of the globe, the reply is that they were primarily due to the unhindered working of the chemical affinities of their constituent molecules as soon as the requisite coolness was obtained. As soon as it became cool enough for oxygen and hydro- gen to unite into a stable compound, they did unite to form vapour of water. As soon as it became cool enough for double salts to exist, then the mutual affinities of simple binary com- pounds and single salts, variously brought into juxtaposition, sufficed to produce double salts. And so on throughout the inorganic world. Here we obtain a hint as to the origin of or- ganic life upon the earth's surface. In accord- ance with the modern dynamic theory of life, we are bound to admit that the higher and less stable aggregations of molecules which consti- 364 THE BEGINNINGS OF LIFE tute protoplasm were built up in just the same way in which the lower and more stable aggre- gations of molecules which constitute a single or a double salt were built up. Dynamically, the only difference between carbonate of ammonia and protoplasm which can be called funda- mental is the greater molecular complexity and consequent instability of the latter. We are bound to admit, then, that as carbonic acid and ammonia, when brought intojuxtaposition, united by virtue of their inherent properties as soon as the diminishing temperature would let them, so also carbon, nitrogen, hydrogen, and oxygen, when brought intojuxtaposition, united by virtue of their inherent properties into higher and higher multiples as fast as the diminishing temperature would let them, until at last living protoplasm was the result of the long-continued process. While by following such considerations as these into greater detail the mode in which pro- toplasm must have arisen may by and by be par- tially comprehended, it is at the same time true that the ultimate mystery — the association of vital properties with the enormously complex chemical compound known as protoplasm — remains unsolved. Why the substance proto- plasm should manifest sundry properties which are not manifested by any of its constituent sub- stances we do not know, and very likely we 3^5 COSMIC PHILOSOPHY shall never know. But whether the mystery be forever insoluble or not, it can in no wise be re- garded as a solitary mystery. It is equally mys- terious that starch or sugar or alcohol should manifest properties not displayed by their ele- ments, oxygen, hydrogen and carbon, when un- combined. It is equally mysterious that a silvery metal and a suffocating gas should by their union become transformed into table-salt. Yet, how- ever mysterious, the fact remains that one result of every chemical synthesis is the manifestation of a new set of properties. The case of living matter or protoplasm is in no wise exceptional. In view of these considerations, it may be held that the evolution of living things is a not im- probable concomitant of the cooling down of any planetary body which contains upon its sur- face the chemical constituents of living matter. It may perhaps turn out that we can no more reproduce in the laboratory the precise groups of conditions under which living matter was first evolved than we can obtain direct testimony as to the language and civilization of our pre- historic ancestors. But, just as it is conceded to be possible, by reasoning upon established phi- lological principles, to obtain some trustworthy results as to the speech and culture of the pre- historic Aryans" so it must be admitted that, by reasoning upon known facts in physical science, we may get some glimpse of the circumstances 366 THE BEGINNINGS OF LIFE which must have attended the origin of living aggregations of matter. By following out this method new light will no doubt eventually be thrown upon the past history of our planet, and a sound basis will be obtained for conjectures re- garding the existence of living organisms upon some of our neighbour worlds. In this account of the matter we have com- pleted, so far as is needful for the purposes of this work, our exposition of the evolution of the earth. Combining the results obtained in the three fore- going chapters, we may contemplate in a single view the wonderful advance in determinate multi- formity which has resulted from the integration of the earth's matter, with the accompanying dis- sipation of its internal motion. We have wit- nessed this process of evolution as manifested in geologic and meterologic phenomena ; we have followed the wondrous differentiations and inte- grations of the molecular motion which the cool- ing and consolidating earth has received from the centre of our system, — and finally, from that very cooling and consolidation upon which all the foregoing phenomena are dependent, we have shown that there must naturally have ensued a progressive chemical heterogeneity, re- sulting at last in the genesis of compounds manifesting those properties which we distin- guish as vital. Thus the continuity in cosmic evolution is grandly exhibited, and we see more 367 COSMIC PHILOSOPHY clearly than ever that between the various pro- vinces of natural phenomena there are no sharp demarcations. As the geologic development of the earth is but a specialized portion of the whole development of the solar system, — a portion which we separate from the rest and assign to a special science, solely for convenience of study; so the development of living matter is but a specialized portion of the whole development of the earth, and it is only for reasons of con- venience that the formation of primeval proto- plasm is assigned to a different science from that which deals with the formation of limestone or silica. Though as we advance from a lower grade of heterogeneity to a higher grade we encounter differences of property or of func- tional manifestation which we may broadly clas- sify as differences of kind, the conclusion is nevertheless forced upon us that such differences of kind are ultimately reducible to differences of degree, and that at bottom there is no break whatever in the continuity of the process of Evolution. It is not pretended, however, that these con- siderations fulfil all the requirements of a scien- tific explanation of the genesis of life. Essen- tially sound as I believe them to be, they do but point out the direction in which an explanation is to be sought. A complete explanation of the origin of life must include not only a statement 368 THE BEGINNINGS OF LIFE of the general conditions under which life origi- nated, such as I have here attempted to offer, but also a statement of the specific combination of circumstances which gave rise to such an event. If Dr. Bastian's theory of archebiosis can be inductively established, it may possibly help us to such a statement. But the consider- ations above adduced make it probable that a wider view of the case is needful than is implied in Dr. Bastian's researches. It seems likely that the genesis of living matter occurred when the general temperature of the earth was very dif- ferent from what it is in the present day ; and in order to engage in a profitable course of ex- perimentation, we must first seek to determine, and then to reproduce if possible, all the requisite conditions associated with that general differ- ence in temperature. Whether this can be done still remains to be seen. That the problem seems hopeless to-day might have been to Comte a sufficient reason for condemning it as vain and profitless. But the history of stellar astronomy may teach us to beware of thus hastily judging the capacity of the future by that of the present. Till within a few years it would have seemed to the wisest man incredible that we should ever be able to determine the direct approach or reces- sion of a star. Yet, from a quarter least expected, a flood of light has been shed upon this most difficult problem. As the doe, in the old fable, vol. n. 369 COSMIC PHILOSOPHY keeping her sound eye landward, was at last shot by archers passing in a boat, so Nature has here been forced to render up her secret in the most unlooked-for way. Through the amazing results obtained by spectrum analysis it has turned out that the heavier difficulty has be- come the lighter one, and that the direct ap- proach or recession of a star, which affords no parallax, is actually easier to measure than its thwart-motion which affords parallax! In like manner the specific solution of the problem of the origin of life need not be despaired of, nor need we wonder if it come from some quite un- suspected quarter. Meanwhile the considerations above alleged will enable us to put the grand phenomenon of the genesis of life into its proper place among the phenomena of telluric evolution. The gulf between the geologic phase of the process and the biologic phase is so far bridged for us that we may approach the study of the latter without misgivings. In the following chapter I shall enu- merate the reasons which compel us to accept the doctrine of the derivation of the more com- plex forms of life from less complex forms ; and because of the interest which just now attaches to the question, I shall make more explicit men- tion of the opposing doctrine of special creations than its own merits would otherwise justify. 37° CHAPTER IX SPECIAL CREATION OR DERIVA- TION?1 WHATEVER may be said in condem- nation or approval of the method of estimating the worth of men and women by an inquiry into their pedigrees, it cannot be denied that there is often much value in such a method of estimating the worth of current ideas. Obviously a theory which was framed in a barbarous age, when men were alike unfamiliar with the conceptions of physical cau- sation and uniformity of law and ignorant of the requirements of a valid scientific hypothesis, and which has survived until the present day, not because it has been uniformly verified by ob- servation or deduction, but because it has been artificially protected from critical scrutiny by incorporation with a system of theological dog- mas assumed to be infallible, — obviously such a theory is at the outset discredited by its pedi- gree. A presumption is at once raised against it, which a critical examination may indeed do away with, but which for the moment cannot fail to 1 [See Introduction, § 18.] 371 COSMIC PHILOSOPHY have some weight with a jury of inquirers fa- miliar with the history of human thinking. On the other hand a theory is a priori accredited by its pedigree when it is framed in a cultivated age by thinkers familiar alike with the special phe- nomena which form its subject matter and with the requirements of scientific hypothesis in gen- eral ; and when, in spite*of theological or senti- mental prejudice, it so thrives under the most rigorous critical scrutiny that each successive decade enlists in its support a greater and greater number of the most competent investigators of nature. I do not say that such an a priori pre- sumption should ever be taken as decisive in favour of any hypothesis. I say only that such considerations do have their weight, and ought to have their weight, in determining the general state of mind which we bring to the discussion of the relative merits of two theories so different in their pedigrees as are the two theories which we are now about to examine. If, with my eyes closed upon all the significant facts which bear upon the question of the origin of species, I were required to decide between two hypotheses, of which the one was framed in an. age when the sky was supposed to be the solid floor of a celestial ocean, while the other was framed in an age when Lagrange and Laplace were determin- ing the conditions of equilibrium of the solar system, I should at once decide, on general 372 SPECIAL CREATION OR DERIVATION? principles, in favour of the latter. And on gen- eral principles I should be quite justified in so deciding. Happily, however, we are not called upon to render a decision, upon this or upon any other scientific question, with our eyes shut. In the present chapter we have to examine two oppos- ing hypotheses relating to the origination of the multitudinous complex forms of animal and vegetal life which surround us. And of these two opposing hypotheses we shall find it not difficult to show that the one is discredited, not only by its pedigree and not only by the im- possible assumptions which it would require us to make, but also by every jot and tittle of the scientific evidence, so far as known, which bears upon the subject ; while the other is not only accredited by its pedigree, and by its requiring us to make no impracticable assumptions, but is also corroborated by all the testimony which the patient interrogation of the facts of nature has succeeded in eliciting. The former hypo- thesis, originating in the crude mythological conceptions of the ancient Hebrews, and un- critically accepted until the time of Lamarck and Goethe, in deference to a tradition which invested these mythological conceptions with a peculiar and unwarranted sacredness, is known as the Doctrine of Special Creations. The latter hypothesis, originating in the methodical study 373 COSMIC PHILOSOPHY of the phenomena of organic life, held by a large number of biologists during the first half of the present century, and of late years accepted by nearly all, may be called the Doctrine of Deri- vation. In describing the special creation hypothesis, we are confronted by an initial difficulty, due to the enormous change which has occurred in men's habits of thinking since the mythopoeic age when it first gained currency. The Hebrew writer, indeed, presents us with a concrete pic- ture of the creation of man, according to which a homogeneous clay model of the human form is, in some inconceivable way, at once trans- muted into the wonderfully heterogeneous com- bination of organs and tissues, with all their definite and highly specialized aptitudes, of which actually living man is made up. But I suppose there are few scientific writers at the present day who would be found willing to risk their reputation for common-sense by attempt- ing to defend such a conception. The few nat- uralists who still make a show of upholding the special creation hypothesis are very care- ful to refrain from anything like a specification of the physical processes which that hypothe- sis may be supposed to imply. When overtly challenged, they find it safest to shrink from the direct encounter, taking refuge in grandilo- quent phrases about " Creative Will " and the 374 SPECIAL CREATION OR DERIVATION ? " free action of an Intelligent Power," very much as the cuttle-fish extricates itself from a disagreeable predicament by hiding in a shower of its own ink. But, however commendable such phrases may be when regarded as a gen- eral confession of faith, they are much worse than useless when employed as substitutes for a scientific description of facts. They only serve to encourage that besetting sin of human think- ing which accepts a play upon words as an equivalent for a legitimate juxtaposition of valid conceptions. When translated, however, from the dialect of mythology into the dialect of science, the special creation hypothesis asserts that the un- told millions of organic molecules of which an adult mammal is composed all rushed together at some appointed instant from divers quarters of the compass, and, spontaneously or in vir- tue of some inexplicable divine sorcery, grouped themselves into the form of an adult organism, some of them arranging themselves into infi- nitely complicated nerve-fibres and ganglionic cells, others into the wonderfully complex con- tractile tissue of muscles, while others again were massed in divers convoluted shapes, as lungs, intestines, blood-vessels, and secreting glands. Or, if a different form of statement be preferred, at one moment we have a background of landscape, with its water and its trees, its 375 COSMIC PHILOSOPHY sands and its herbage, and at the next succeed- ing moment we have in the foreground an ox or a man, or, according to another view, a herd of oxen and a group of men, and all this with- out any assignable group of physical anteced- ents intervening ! He who can believe that St. Goar, of Treves, transformed a sunbeam into a hat-peg, or that men were once changed into werewolves by putting on an enchanted gir- dle, or that Joshua and Cardinal Ximenes con- strained the earth to pause in its rotation, will probably find no difficulty in accepting such a hypothesis to account for the origin of men and oxen. To persons in such a stage of culture it is no obstacle to any hypothesis that it involves an assumption as to divine interposition which is incapable of scientific investigation and un- interpretable in terms of human experience. It can hardly be denied, however, that any hy- pothesis which involves such an assumption is at once excluded from the pale of science and relegated to the regions of mythology, where it may continue to satisfy those to whom mytho- logic interpretations of natural phenomena still seem admissible, but can hardly be deemed of much account by the scientific inquirer. On the other hand, according to the doctrine of derivation, the more complex plants and ani- mals are the slowly modified descendants of less complex plants and animals, and these in 376 SPECIAL CREATION OR DERIVATION? turn were the slowly modified descendants of still less complex plants and animals, and so on until we converge to those primitive organisms which are not definable either as animal or as vegetal, but which in their lowest forms are mere shreds of jelly-like protoplasm, such as the spontaneous combination of colloidal clusters of organic molecules might well be capable of originating under appropriate conditions, after the manner pointed out in the preceding chap- ter. The agencies by which this slow derivation of higher from lower forms has been effected are agencies such as are daily seen in operation about us ; namely, individual variation, adapta- tion to environing circumstances, and hereditary transmission of individual peculiarities. Obvi- ously such a hypothesis is not only highly credi- ble in itself, since it only alleges that the growth of a complex organism from a simple globule of protoplasm, which is accomplished in every case of individual evolution, has also been accom- plished during the evolution of an immensely long series of individuals ; but it is also a purely scientific hypothesis, since it appeals to no agen- cies save such as are known to be in operation, and involves no assumptions which cannot, sooner or later, be subjected to a crucial test. These preliminary considerations show how strong is the legitimate presumption in favour of the theory of derivation. But the case is not 377 COSMIC PHILOSOPHY to be dismissed upon these summary, though forcible considerations. To the general reasons here assigned for preferring the theory of deri- vation to the theory of special creations, a scien- tific survey of the phenomena will add a num- ber of special reasons. Four kinds of arguments in favour of the hypothesis of derivation are furnished respectively by the Classification of plants and animals, by their Embryology, by their Morphology, and by their Distribution in space and_time. I shall devote the present chap- ter to the consideration of these four classes of arguments, reserving for the following chap- ter the explanation of the agencies which have been at work in forwarding the process of de- velopment. I. The facts which are epitomized in tabu- lar classifications of animals and plants are so familiar to us that we seldom stop to reflect upon their true significance. And in any bald state- ment of them which might here be made, the impression of triteness would perhaps be so strong as to prevent that significance from be- ing duly realized, save by the student of natural history. To present in the strongest light the evidentiary value of these facts, I shall there- fore have recourse to an analogous series of facts in a quite distinct science, where the sig- nificance of the classification is illustrated by the known history of the phenomena which are clas- 378 SPECIAL CREATION OR DERIVATION? sified. Like the sciences of zoology and botany, the science of philology is preeminently a clas- sificatory science, using the method of compari- son as its chief implement of inductive research. And philology, at least so far as the study of the Aryan language is concerned, has been carried to such a high degree of scientific perfection, as regards the accuracy of its processes and the certainty of its results, that we may safely gather from it such illustrations as suit our present purpose. The various Aryan or Indo-European lan- guages are demonstrably descended from a single ancestral language, in the same sense in which the various modern Romanic languages are all descended from the vulgar Latin of the West- ern Empire. By slow dialectic variations in pronunciation, and in the use of syntactical de- vices for building up sentences, these languages have been imperceptibly differentiated from a single primeval language, until they are now so unlike that not one of them is intelligible, save after careful study, to the speakers of another. The minute variations, of which the cumulative result is this manifold unlikeness, have not pro- ceeded at haphazard ; but they have all along been determined by certain phonetic conditions, which have been so thoroughly generalized that philologists can now occasionally reconstruct extinct words, after a fashion somewhat similar 379 COSMIC PHILOSOPHY to that in which Professor Huxley would, I presume, reconstruct an extinct animal upon seeing one of its fossilized bones or teeth. But what now chiefly concerns us is the fact that all existing Aryan languages are the modi- fied descendants of a common progenitor. Bear- ing this in mind, let us note sundry features of the classification of these languages. In the first place, it is impossible to arrange them in any linear series which will truly represent their relations to each other. In some respects Sanskrit is nearest the original type, in other respects it is Lithuanian which shows the least departure, in other respects it is Old Irish, and in yet others it is Latin. Even if we decide to make a compromise, and to begin with Sanskrit, as being on the whole the least modified of these languages, we cannot stir many steps without getting into difficulties. Suppose we say San- skrit, Lithuanian, Old Irish, Latin, Old Slavic, Zend, Greek, Gothic, Old German. See now what we have been doing ! We have indeed got old Irish and Latin close together, as they ought to be, and we have done right in putting Gothic and Old German side by side ; but we have been obliged to thrust in half a dozen lan- guages between Sanskrit and Zend, and between Latin and Greek there is a similar unseemly divorce. When we come to take in the later dialects, the confusion becomes still more hope- 380 SPECIAL CREATION OR DERIVATION? less. If after Sanskrit we put in Prakrit and Pali, Urdu and Bengali, and a dozen other de- rivatives, we must then jump back to Latin, for instance, and after following along through Italian, Spanish, French, and their sister dia- lects, jump back again to some ancient language. Obviously this is violating all the requirements of proper classification, which consists in putting nearest together those objects which are nearest alike. In view of these and other kindred difficulties, philologists have long since agreed to arrange the Aryan family of languages in divergent and re- divergent groups and sub-groups, along lines which ramify like the branches, branchlets, and twigs of a tree. Let us trace the pedigree of the French and English languages according to this principle of classification as elaborated by Schleicher, remembering that while other philologists have objected to some of the details of the classification,1 all agree, and must agree, in the fundamental principle. Starting, then, from the Aryan mother-tongue, we first en- counter two diverging lines of development, represented by two extinct phases of language, i Indeed, it is possible that the primary division should be into Eastern and Western, or European and Asiatic, rather than Northern and Southern Aryan. But the future decision of this question will not alter the principle upon which the classification is founded and which it is here cited to exemplify. 381 COSMIC PHILOSOPHY which we may call the South Aryan and North Aryan. Following the progress of the South Aryan, we find it diverging on the one hand into Indo-Iranian, and on the other hand into the parental form of the Hellenic, Italic, and Keltic languages. Neglecting the other branches, and following only the Italic, we find the di- vergent forms of this exemplified in Umbrian, Oscan, and Latin ; and again, following the career only of the latter branch, we arrive at French and its kindred Romanic dialects. On the other hand, as we follow the North Aryan line, we find it first dividing into Teutonic and Slavo-Lettish. Neglecting the latter, we observe the Teutonic again diverging into Gothic, Old Norse, and Old German. Following only the last of these, we may observe it bifurcating into High and Low German, from the latter of which is derived the English which we speak. Now if we take a general survey of this family-tree, we find that kindred words in lan- guages down near the trunk resemble each other closely, while kindred words in languages high up on the twigs have often well-nigh lost all traces of their primitive family likeness. To be sure we can still recognize the English daughter in the Sanskrit duhitr, but such strong resemblances are not usual, and it is only too easy to look at a page of Sanskrit without realiz- ing its kinship with English. But to show how 382 SPECIAL CREATION OR DERIVATION? the likeness diminishes as we recede from the original source, let us consider two English words — one of which has come to us by nat- ural descent, through the North Aryan line, while the other has come to us, by adoption, from the South Aryan stock. No two words could well be more unlike than the words pen and feather. Of these the latter is a purely English word, while the former is a word we have adopted from the Latin. Now great as is the difference between these two words, it very nearly disappears when we have recourse to their Old Aryan prototypes pata-tra and pat- na. Pat is a word designating flight. Pata-tra and pat-na are words designating a wing, or instrument used in flying. In the course of the North Aryan development pata-tra becomes fath-thra and finally feather ', just as patar be- comes father, in accordance with a general ten- dency of the Teutonic toward aspirating the hard mutes of the old language ; while on the other hand, in the course of the South Arvan development pat-na became first pes-na and then pen-na, in accordance with a general tendency of the Latin toward the assimilation of contigu- ous consonants. Who but a linguist, knowing the history of the words, and familiar with the general principles of phonetic change, would suspect that words apparently so distinct as pen and feather could be referred so nearly to a 3*3 COSMIC PHILOSOPHY common origin ? Or consider the French larme and the English tear. These words are de- monstrably descended from the same ancestral form dakru-ma. But while the South Aryan form has undergone one kind of change into the Latin lacru-ma, and thence into the French larme ; the North Aryan form has undergone another kind of change into the Old German tagr, and thence into the English tear. Thus in general, as we go backward in time, we find the lines of linguistic development draw- ing together. Between the various Low-Dutch dialects spoken along the north coast of Ger- many, the differences are hardly great enough to interfere with mutual intelligibility. Again, between Portuguese and Spanish the differences are so small that one who is well acquainted with Spanish can often get the sense of many pages in a Portuguese book without having specially studied the latter language. But German and Spanish have few mutually intelligible words in common, and their differences in idioms and in structure of sentences are no less conspicuous. While it might be possible to maintain that Dutch and Platt-Deutsch, or that Portuguese and Spanish, are only dialects of the same lan- guage, no one would hesitate about calling Teu- tonic and Romance quite different forms of lan- guage. Yet we need only go back far enough to find the demarcation quite as obscure in the one 384 SPECIAL CREATION OR DERIVATION? case as in the other ; for Teutonic and Romance began as the northern and southern dialects of the same Old Aryan language. In similar wise we may say that, even with the keenest linguis- tic instinct, it would be difficult to decipher a line of modern Persian by reason of its kinship with modern Greek ; while yet it is undeniable that the Persian spoken by the officers of Xerxes was strikingly similar to the Greek spoken by Demaratos and Leonidas. In citing this example from the phenomena of language, I do not cite it as direct testimony in favour of the theory of derivation in biology. Because tear and larme can be traced back to a common form, it does not follow that the pig and the horse have a common ancestor. Yet, while the linguistic parallel is by no means avail- able as direct testimony in a biological question, it has nevertheless a logical value so important that zoologists as eminent as Haeckel and phi- lologists as profound as Schleicher have not failed to insist upon it. What we see exempli- fied in these linguistic phenomena is the way in which a classification must be framed in all cases where we have to express complex genetic relation- ships. We see that where a multitude of objects are associated by a common genesis, we cannot classify them in a linear series, but only in groups and sub-groups, diverging from a common trunk, like the branches and twigs of what we very aptly TOL. II. 3 5 COSMIC PHILOSOPHY term a " family-tree." And on the general prin- ciples of hereditary relationship, we see that ob- jects near the common trunk will depart less widely from the primitive ancestral type, and will therefore resemble each other more closely, than objects far up on the ends of the branches. A comparison of the different races of Aryan men would bring out the same results as the comparison of their languages. After making all allowances for the intermixture of the Aryans with divers aboriginal races in Europe and Asia, it remains generally admitted that every Aryan language is spoken by men who are predomi- nantly Aryan in blood. Now it would be im- possible to arrange Hindus, Greeks, Italians, Russians, Germans, and English in any linear series. We can only divide and subdivide, ar- ranging them in groups that diverge and re- diverge. Such must always be the case when we have to deal with phenomena due to hereditary relationship * and wherever we find a set of ob- jects thus arranged in groups within groups, converging at the bottom and diverging at the top, we have the very strongest possible prima facie ground for asserting hereditary relation- ship. Coming now to our main thesis, we can be- gin to appreciate the strength of the evidence in favour of the derivation theory, which is furnished by the classification of animals, as ef- 386 SPECIAL CREATION OR DERIVATION? fected by Cuvier and Von Baer, and still further elaborated by Huxley and Haeckel. Previous to Cuvier many eminent naturalists endeavoured to arrange the animal kingdom in a series of lineally ascending groups. The illustrious La- marck did so ; and the result was that he placed oysters and snails higher up than bees and but- terflies. Blainville did better, having come as near as possible to surmounting insurmountable obstacles, but he nevertheless is forced to put cirrhipeds and myriapoda above the cuttle-fish. It was a great step in advance when Cuvier showed that there are at least four distinct types of animal structure, and that no linear series can be framed ; although Professor Agassiz un- doubtedly transgressed the limits of scientific inquiry when he attempted to explain the coex- istence of these distinct types by resuscitating from its moss-covered tomb the Platonic theory of Ideas, and impressing it into the service of natural theology. Nevertheless in his remark- able " Essay on Classification," Professor Ag- assiz more than atones for these metaphysical aberrations by the conclusiveness with which he shows the impossibility of making a linear classification of animals. In such a series the lowest of vertebrates, the unintelligent amphi- oxes, would rank above the wonderfully organ- ized crabs, ants, and butterflies. The degraded lepidosiren would take precedence of the sal- 387 COSMIC PHILOSOPHY mon, and the lowly organized duck-bill, as being a mammal, would be placed above the parrot and the falcon. Or if we attempted to escape these difficulties by ranking our animals in a series according to their general complexity of organi- zation, neglecting their typical differences of structure, our whole classification would be thrown into senseless confusion. Parrots and honey-bees would be thrust in among mammals, and not only classes, but even orders, and per- haps families, of annulosa would have to be di- vided, to make room for intrusive echinoderms and mollusks. In view of these difficulties, as Professor Huxley and Professor Haeckel have shown, the only feasible manner of arranging the animal kingdom is in a number of diverging or branch- ing lines, like the boughs and twigs of a tree. Starting from the amoeba and its kindred, which are neither animal nor vegetal in charac- ter, we encounter two diverging lines of devel- opment represented respectively — according to Haeckel's surmise — by those protists with harder envelopes which are the predecessors of the vegetable kingdom, and those protists with softer envelopes which are the forerunners of the more mobile animal type of organization.1 i Though I leave this sentence as it was written three years ago, it must not be understood as an unqualified endorsement of Professor Haeckel's attempt to erect a third kingdom — of 388 SPECIAL CREATION OR DERIVATION? Confining our attention to animals, we meet first with the coelenterata, including sponges, corals, and medusas, characterized by the union of masses of amceba-like units, with but little specialization of structure or of function. Be- side these lowly forms, but not immediately above any one of them, we find echinoderms starting ofFin one direction, worms orannuloida in a second, and molluscoida in a third. Fol- lowing the first road, we stop short with echino- derms. But on the second, we find annuloid worms succeeded by articulata, or true annu- losa — which re-diverge in sundry directions, reaching the greatest divergence from the primi- tive forms in the crabs, spiders, and ants. On the third road, we find the molluscoid worms diverging into mollusks and vertebrates. On the one hand, through the bryozoa we are Protists — comprising such organisms as are neither distinctively animal nor vegetable. There is something to be said in behalf of such an arrangement, provided no attempt be made to draw a hard and fast line between the protistic and the two higher kingdoms ; and I suppose that no follower of Haeckel is likely to make such an attempt. Since a bacterium or a vibrio is clearly not an animal, and clearly not a vegetable, while it is clearly a living thing, there would seem to be some con- venience in having a region to which to assign it. I should, however, regard this "region " of protists, or lowest organ- isms, as not stricdy a " kingdom," but rather as the indefi- nite border-land between the animal and vegetal worlds on the one hand and the realm of inorganic existence on the other. 389 COSMIC PHILOSOPHY gradually led to the true mollusks ; while on the other hand, the tunicata, of which the ascidian or " pitcher " (the primitive " tadpole " of unsci- entific ridiculers of Darwinism) is the most fa- miliar form, lead us directly to the vertebrates.1 At first the vertebrata are all fishes, if such mol- 1 Kowalewsky has discovered some wonderful likenesses between the embryonic development of the ascidian and that of the amphioxus or lowest known vertebrate. Of all the " missing links," the assumed absence of which is so persist- ently cited by the adherents of the dogma of fixity of species, the most important one would here, appear to have been found ; for it is a link which connects the complex and highly evolved vertebrate with a very lowly form which passes its natural existence rooted plant-like to the soil, or rather to the sea-bottom. The ascidian cannot, indeed, be regarded as typi- fying the direct ancestors of the vertebrata. It is a curiously aberrant and degraded form, and its own progenitors had doubtless once " seen better days." In its embryonic state it possesses a well-marked vertebral column, and it behaves in general very much as if it were going to grow to something like the amphioxus. But it afterwards falls considerably short of this mark. Already in early life its vertebras begin to become "rudimentary " or evanescent ; and when fully matured, it stops swimming about after its prey, and, striking root in the sub-marine soil, remains thereafter standing, with its broad pitcher-like mouth ever in readiness to suck down such organ- isms floating by as may serve for its nutriment. That verte- brae should be found in the embryo of such an animal is a most interesting and striking fact. It would seem to mark the asci- dian as a retrograded offshoot of those primitive forms on the way toward assuming the vertebrate structure, of which the more fortunate ones succeeded in leaving as their representative the amphioxus. 390 SPECIAL CREATION OR DERIVATION? lusk-like creatures as the amphioxus can strictly be included among fishes ; but presently here too the lines begin to diverge, and we encounter reptiles and birds on the one hand, and mam- mals on the other, all three being related to fishes through the remarkable structures of liv- ing and extinct batrachia. Such, as stated with crude brevity, is the classification of animals most in accordance with our present knowledge. Now from first to last, the farther we trace any one line of develop- ment, the more widely we find it diverging from other lines which originated in the same point. The higher insects and crustaceans are not at all like worms ; but the myriapoda, the lower crustaceans, and the caterpillars of higher in- sects, are like worms. Viewed at the upper ends of the scale, the mollusks are widely different from the vertebrates ; viewed at the lower end, the difference almost vanishes — the amphioxus being closely similar in structure to the asci- dians, whose embryos present rudiments of a vertebral column. No two animals could well be more strikingly unlike than a wren and an elephant ; yet the lowest known mammal, the Australian duck-bill, possesses many bird-like characteristics. In the man and the oak we get perhaps the widest possible amount of diver- gence between organisms ; yet at the bottom of the animal and vegetal kingdoms we find crea- 391 COSMIC PHILOSOPHY tures like the amoeba and protococcus, which cannot be classified as either animal or vegetal, because they are as much one as the other. Moreover, as we go back in time, we find the lines of development, now so widely distant from each other, continually drawing together. As a general rule, extinct animals are less spe- cialized than surviving animals ; and the same is true of plants. The ancient animal departed less widely from the general type of the class or sub - kingdom to which he belonged than the modern animal. The monotremata, which of all mammals are the least remote from rep- tiles and birds, are at the same time the oldest. In the teleosts or true fishes the differential characteristics of the vertebrate type are more strongly pronounced than in the older selachi- ans, to which order belongs the shark. Far back in secondary times we find lizards strongly resembling fishes, and other saurian creatures which differ little from birds. Confining our attention to any particular group, such as that which embraces the ruminants and pachyderms, we find the hipparion of the Eocene epoch less specialized than either of his later kindred, the horse, ass, zebra, and quagga ; while the gap between such dissimilar animals as the pig and the camel is to a great extent filled by transi- tional forms found in various tertiary strata. Again, it hardly needs stating that, as we 392 SPECIAL CREATION OR DERIVATION? proceed from a general survey of any group of animals or plants to a survey of the sub-groups of which it is made up, we find the differences constantly growing less numerous and less fun- damental. The differences between the ox and the lion are many and important — but be- tween the various members of the order car- nivora, between the lion and the wolf or the bear, the differences are less. As we descend another step, and compare lions with lynxes, jaguars, leopards, and cats, which belong to the same family, we find the points of divergence fewer and less characteristic. Between wild and do- mestic cats there is still less difference ; while between the various breeds of the domestic cat the distinctions are limited to superficial char- acteristics of size, colour, and general intelli- gence. Hence, when classifying contemporary organisms of high development, naturalists are never in doubt as to the class or order, and but seldom as to the family ; while they are not unfrequently in doubt as to the genus, and are continually disputing as to the species or variety to which a given form belongs. As we descend in the scale of development, and go back in geologic time, the determination of genera becomes more and more difficult. Doubts frequently arise with reference to family, order, and class. And at last even the sub-kingdom becomes doubtful, as is strikingly shown by the 393 COSMIC PHILOSOPHY difficulty in classifying the lowly animals pro- visionally grouped by Cuvier as radiata, when contrasted with the ease with which naturalists distinguish the higher sub-kingdoms. Now all this complex arrangement of organ- isms in groups within groups, resembling each other at the bottom of the scale and differing most widely at the top, is just the arrangement which, as we have seen, must result from ge- netic relationship ; and upon any other theory than that of derivation it is utterly inexplicable. If each species has been separately created, no reason can be assigned for such an arrangement, — unless perchance some one can be found hardy enough to maintain that it was intended as a snare and a delusion for human intelligence. The old opponents of geology, who strove to maintain at whatever cost the scientific credit of the Mosaic myth of the creation, asserted that fossil plants and animals were created already dead and petrified, just for the fun of the thing. Manifestly those persons take a quite similar position who pretend that God created sepa- rately the horse, ass, zebra, and quagga, having previously created a beast enough like all of them to be their common grandfather. Indeed, so powerful is this argument from classification that it has always seemed to me sufficient by it- self to decide the case in favour of the theory of derivation. In my own case, the facts pre- 394 SPECIAL CREATION OR DERIVATION? sented in Professor Agassiz's " Essay on Classi- fication " went far toward producing conviction before the publication of Mr. Darwin's work on the " Origin of Species," where the significance of such facts is clearly pointed out and strongly insisted upon. II. An equally powerful argument is fur- nished by the embryonic development of organ- isms. As Von Baer long ago pointed out, the germs of all animals are at the outset exactly like each other ; but in the process of develop- ment each germ acquires first the differential characteristics of the sub-kingdom to which it belongs, then successively the characteristics of its class, order, family, genus, species, and race. For example the germ-cell of a man is not only- indistinguishable from the germ-cell of a dog, a chicken, or a tortoise, but it is like the adult form of an amoeba or a protococcus, which are nothing but simple cells. Four weeks after con- ception the embryos of the man and the dog can hardly be distinguished from each other, but have become perceptibly different from the corresponding embryos of the chicken and tor- toise. At eight weeks a few points of difference between the dog and the man become percep- tible ; the tail is shorter in the human embrvo, and the cerebrum and cerebellum have become larger, relatively to the corpora quadrigemina, than in the embryo of the dog ; but these dif- 4 395 COSMIC PHILOSOPHY ferences are less striking than those which sepa- rate the two mammals on the one hand from the reptile and bird on the other. At a later stage the human embryo becomes still more unlike that of the dog, acquiring characteristics peculiar to the order of primates to which man belongs. Lastly, the fetus of civilized man, at seven months, is entirely human in appearance, but still has not thoroughly acquired the phy- sical attributes which distinguish the civilized man from the Australian or the negro. On the evolution theory these phenomena are explicable as due to the integration or sum- ming-up of adaptive processes, by which modifi- cations slowly acquired through generations of ancestral organisms are more and more rapidly repeated in the embryos. Hence, as Professor Haeckel has elaborately proved, we must ex- pect to find the phenomena of embryology in complete harmony with the facts of the geologi- cal succession of organisms. Observation shows that the harmony is complete ; and again, unless we are to suppose that the phenomena of nature have been maliciously arranged with the ex- press purpose of cheating us, we have no choice but to accept that harmony as proof of the truth of the evolution theory. Kindred evidence is furnished by the well- known fact that many animals, during their fcetal life, acquire organs like those possessed 396 SPECIAL CREATION OR DERIVATION? by adults of allied species, but which, having no functions to discharge, are after a while absorbed or dwindle into mere rudiments. The mamma- lian embryo at first circulates its blood through a vascular system like the gills of fishes ; after- wards this is replaced by a vascular membrane called the allantois, like the membrane which replaces gills in the development of birds and reptiles. Neither of these structures is useful to the embryo for the purpose of aerating its blood, and there is no possible explanation of their appearance in untold millions of mammals, un- less we admit that they are due to inheritance from the amphibious ancestors of the mamma- lian class. Of like meaning are such facts as the presence of useless teeth in the jaws of foetal whales, and in the beaks of certain embryonic birds ; the rudiments of a pelvis and hind-limbs in many snakes ; the wings, firmly fastened under their wing-cases, in insects which do not fly ; the cascum, or blind intestine, and the ter- minal vertebrae in man ; and the incisor teeth in calves and other ruminants, which never cut through the gum. No explanation can be given of such phenomena, save on the theory of in- heritance ; for the pompous statement, which we sometimes hear, that such organs have been created " for the sake of symmetry, and in order to complete the scheme of nature," is no expla- nation at all. As Mr. Darwin pertinently asks. 397 COSMIC PHILOSOPHY "Would it be thought sufficient to say that be- cause planets revolve in elliptic courses round the sun, satellites follow the same course round their planets, for the sake of symmetry, and to complete the scheme of nature ? " Moreover, if we were to rest content with this arbitrary assumption, we must needs confess that the symmetry of nature has been but imperfectly wrought out ; for the rudimentary organs which, on this hypothesis, ought always to be present are often entirely wanting. In this connection the history of the long exploded hypothesis of Preformation becomes very instructive. The argument is ably pre- sented by Mr. Lewes, in a series of essays on Darwinism, which are still buried among the back numbers of the " Fortnightly Review," but which, it is to be hoped, will presently be reprinted in some more generally accessible form. Mr. Lewes calls attention to the fact that those who still profess to find it incredible that a complex organism should have been devel- oped through long ages and through countless intermediate forms from a unicellular creature like the amoeba, nevertheless find nothing in- credible in the demonstrated fact that complex organisms are developed in a few weeks or months from minute homogeneous germ-cells. Now it is instructive to note that to the physi- ologists of a century ago the latter process of 393 SPECIAL CREATION OR DERIVATION? development seemed quite as incredible as the former. The process by which a structureless germ, assimilating nutriment from the blood of the parent organism, becomes gradually differ- entiated into such an amazingly complex crea- ture as a man or an elephant was not at that time understood. It seemed utterly incredible that a human infant could have so recently been a simple globule of protoplasm. It was accord- ingly maintained that, since an infant resembles an adult in most respects save that of size, the original germ must be a minute copy of the in- fant. From the germ to the adult man there was no increase in complexity, there was only increase in dimensions. As a necessary conse- quence the germs of each generation were con- tained within the germs of the next preceding generation ; so that in Mother Eve were con- tained the miniature originals of the entire hu- man race, completely shaped in every feature, and shut up one within another, like a series of Chinese boxes ! This hypothesis now strikes us as superla- tively absurd. But it has been upheld by some of the greatest biologists who have ever lived, — by Swammerdamm, Haller, Bonnet, Reau- mur, and Cuvier, — and to my mind it is less grotesque than the hypothesis of special crea- tions. But what now concerns us is the fact that the doom of the latter hypothesis is inevi- 399 COSMIC PHILOSOPHY tably involved in the destruction of the former. For not only may it be forcibly argued " that we can no more understand the appearance of a new organism which is not the modification of some already existing organism than we can understand the sudden appearance of a new organ which is not the modification of some existing structure," but there was yet another deadly weapon lying concealed amid the mass of evidence with which Wolff and Von Baer overthrew the preformation theory. Why this roundabout method, above described, in which the germs of the higher organisms are seen to develop ? Why does a mammal begin to de- velop as if it were going to become a fish, and then, changing its course, act as if it were going to become a reptile or bird, and only after much delay assume the peculiar characteristics of mammals ? The human embryo, for example, begins with gill-like slits on each side of the neck, up to which the arteries run in arching branches, as in a fish ; the heart is at first a simple pulsating chamber, like the heart of the lowest fishes ; at a later period there is a mov- able tail considerably longer than the legs ; the great toe projects sideways from the foot, like the toes of adult monkeys and apes ; and, dur- ing the sixth month, the whole body is covered very thickly with hair, extending even over the face and ears, everywhere, indeed, save on the 400 SPECIAL CREATION OR DERIVATION? lower sides of the hands and feet, which are also bare in the adult forms of other mammals. In like manner, the tadpole of the black sala- mander, which is not born until it is fully formed, and which never swims, nevertheless has gills as elaborately feathered as those which, in the tadpoles of other salamanders, are des- tined for use. Treatises on embryology are crowded with just such facts as these. Now why is it that, in all cases, before a complex organism " can attain the structure which dis- tinguishes it, there must be an evolution of forms which distinguish the structures of organ- isms lower in the series ? " " None of these phases have any adaptation to the future state of the animal ; many of them have no adap- tation even to its embryonic state." On the hypothesis that each species of organisms was independently built up by a Divine Architect, how are we to explain these circuitous proceed- ings ? " What," asks Mr. Lewes, " should we say to an architect who was unable, or being able was obstinately unwilling, to erect a palace except by first using his materials in the shape of a hut, then pulling it down and rebuilding them as a cottage, then adding story to story and room to room, not with any reference to the ultimate purposes of the palace, but wholly with reference to the way in which houses were constructed in ancient times ? What should we VOL. II 40I COSMIC PHILOSOPHY say to the architect who could not directly form a museum out of bricks and mortar, but was forced to begin as if going to build a mansion ; and after proceeding some way in this direction altered his plan into a palace and that again into a museum ? Yet this is the sort of succes- sion on which organisms are constructed." It is out of this very uncomfortable corner that metaphysical naturalists have sometimes at- tempted to slip, by gravely asserting that Na- ture is obliged to work tentatively ! Thus we see that the habit of personifying Nature may sometimes be made to serve an argumentative purpose. When theologians are molested by uncomfortable questions concerning the exist- ence of phenomena which seem incompatible with the perfect wisdom of an anthropomor- phic Deity, they are wont to ascribe them to the Devil. It must be acknowledged that met- aphysical naturalists practise a more graceful, though not a more candid, method of evasion when they erect Nature (spelled with a capital) into a person distinct from phenomena, and coolly ascribe to her the shortcomings which they dare not lay to the account of a personal Deity. Viewed in the light of a scientific logic, this argument from embryology, like the argument from classification, seems powerful enough, when taken alone, to decide the case in favour 402 SPECIAL CREATION OR DERIVATION? of the derivation-theory. As already hinted, these phenomena are in general explicable by the Doctrine of Evolution. But to the special creation hypothesis they are unmanageable stumbling-blocks. Even without any profound knowledge of embryology, one may readily see that if the tadpoles of the black salamander were anciently born as tadpoles, and swam in the water, they may still retain their exquisite gills while nourished to a later stage of devel- opment in the maternal organism. But on the opposite theory the existence of these gills is meaningless. III. The equally significant facts of mor- phology may be more concisely presented. Why, unless through common inheritance, should all the vertebrata be constructed on the same type ? Structurally considered, man, ele- phant, mouse, ostrich, humming-bird, tortoise, snake, frog, crocodile, halibut, herring, and shark are but different modifications of one common form. It is a familiar fact that the arms of men and apes, the fore-legs of quad- rupeds, the paddles of cetacea, the wings of birds, and the breast-fins of fishes are structur- ally identical, being developed from the same embryonal rudiments. Externally there is but little resemblance between the human hand and the hoof of a horse ; yet anatomy shows that the horse's hoof is made up of claws or fingers 403 COSMIC PHILOSOPHY firmly soldered together. Turning to the annu- losa, we find that all insects and crustaceans — dragon-flies and mosquitoes as well as crabs and shrimps — are composed of just twenty seg- ments. " What now," asks Mr. Spencer, " can be the meaning of this community of structure among these hundreds of thousands of species filling the air, burrowing in the earth, swimming in the water, creeping about among the sea- weed, and having such enormous differences of size, outline, and substance that no community would be suspected between them ? Why, un- der the down-covered body of the moth and under the hard wing-cases of the beetle, should there be discovered the same number of divi- sions as in the calcareous framework of the lobster?" But two answers are possible. We may either say, with the Mussulman, " it so pleased Allah, whose name be exalted ; " or we may honestly acknowledge the scientific im- plication that such community of structure is strong evidence in favour of community of origin. IV. The facts of geographical distribution and geological succession are likewise in com- plete harmony with the development theory. On the hypothesis of special creations, no good reason can be given why the extinct animals found in any geographical area should resemble, both in general structure and in special modifi- 404 SPECIAL CREATION OR DERIVATION? cations, the animals which now live in the same area. Thus the fossil mammals of Australia are chiefly marsupials, allied in structure to the marsupials which now inhabit that continent ; the extinct mammals of South America closely resemble living sloths, armadillos, and ant-eaters. " I was so much impressed with these facts," says Mr. Darwin, " that I strongly insisted, in 1839 and 1845, on this wonderful relationship in the same continent between the dead and the living. Professor Owen has subsequently ex- tended the same generalization to the mammals of the Old World. We see the same law in this author's restorations of the extinct and gigantic birds of New Zealand. We see it also in the birds of the caves of Brazil. Mr. Woodward has shown that the same law holds good with sea-shells. Other cases could be added, as the relation between the extinct and living land- shells of Madeira, and between the extinct and living brackish-water shells of the Aralo-Caspian Sea." It has indeed been urged, by upholders of the special creation hypothesis, that these strik- ing resemblances may be explained by suppos- ing each species to have been created in strict adaptation to the conditions of life surrounding it. That is to say, God has continued to create edentata in South America and marsupials in Australia, because these two continents are best 405 COSMIC PHILOSOPHY fitted for the comfortable maintenance respec- tively of edentata and of marsupials. Stubborn facts, however, are opposed to this theory of the methods of Divine working. The assump- tion that each species is best adapted to its own habitat is refuted by such facts as the now rapidly progressing extermination of native ani- mals and plants in New Zealand by European organisms lately carried there. Cow-grass, this- tles, dock, and white clover flourish more vig- orously in New Zealand than in England, and within a few years have almost displaced the native grasses ; while the native rats and flies are fast disappearing before the rats and flies imported from Europe. The assumption is still more strikingly refuted by a comparison of the forms of life which inhabit Australia with those which inhabit the southern extremities of Africa and South America. These three tracts of land are very similar in their physical condi- tions, and yet, as Mr. Darwin has observed, it would be impossible to point out three faunas and floras more strikingly dissimilar. If the dis- tribution of organisms were miraculously deter- mined in accordance with their fitness to their surrounding conditions, the fauna of South America in latitude 350 ought to resemble the fauna of Australia in the same latitude more closely than it resembles the fauna of South America in latitudes north of 250. The case is 406 SPECIAL CREATION OR DERIVATION? just the reverse. Again ther^ is no apprecia- ble difference between the conditions of exists ence in the seas east and west of the isthmus of Panama ; and, according to the assumption of the special-creationists, their marine faunas ought to be almost exactly alike. In fact no two marine faunas are more completely distinct. Hardly a fish, mollusk, or crustacean is com- mon to the eastern and western shores. This is because the isthmus, though narrow, is im- passable for marine organisms. On the other hand, wherever groups of organisms are not pre- vented by impassable barriers from spreading over wide tracts of country or of sea, we find distinct but closely allied species widely spread and living among the most diverse conditions. The inference is obvious that the population of different zoological and botanical areas is due to migration, and not to special creation. Where organisms have a chance to migrate, they mi- grate and become adapted, by slight specific changes, to the new circumstances which they encounter. But where there is a barrier between one area and another, there we find complete diversity between the inhabitants of the two areas, although there is no reason for such diversity, save the impossibility of getting across the barrier. Of like meaning is the fact that batrachians and terrestrial mammals are never found indigenous upon oceanic islands'. As 407 COSMIC PHILOSOPHY Mr. Darwin observes, " the general absence of frogs and toads from oceanic islands cannot be accounted for by their physical conditions ; in- deed it seems that islands are peculiarly well fitted for these animals ; for frogs have been introduced into Madeira, the Azores, and Mau- ritius, and have multiplied so as to become a nuisance. But as these animals and their spawn are known to be immediately killed by sea- water, there would be great difficulty in their transportal across the sea, and therefore on my view we can see why they do not exist on any oceanic island. But why, on the theory of crea- tion, they should not have been created there it would be very difficult to explain." That terrestrial mammals cannot cross the sea is ob- vious ; but bats and birds, which can fly, are found on many oceanic islands. In an admir- able essay on the migrations of organisms, con- sidered with reference to the Darwinian theory, Professor Moritz Wagner has collected many similar examples. From personal observations in North Africa, in Western Asia, in Hungary, and in America, this veteran naturalist educes the general conclusion that the limits within which allied species are found are determined by impassable natural barriers. Coleoptera with their wings fastened down under their wing- cases are specifically different on the opposite shores of small rivers ; while butterflies and 408 SPECIAL CREATION OR DERIVATION? hymenoptera range over large tracts of inland country, but are stopped by such obstacles as the Straits of Gibraltar. On opposite sides of the Andes, the conditions of existence differ but little, while on the north and south sides of the Caucasus the difference in climate is ex- treme. Yet the Andes are much the more diffi- cult to cross, and accordingly the fauna which they separate are much more unlike than the fauna separated by the Caucasus. In like man- ner the Galapagos Islands, situated some six hundred miles from the South American con- tinent, possess a fauna which, with the excep- tion of a few birds, is generically distinct from all other faunas. Yet though generically distinct, it is South American in type, and most resem- bles the fauna of Chili, the nearest mainland. Furthermore, among the animals living on the different islands of the group, we find specific diversity along with generic identity. So also Madeira " is inhabited by a wonderful number of peculiar land-shells, whereas not one species of sea-shell is peculiar to its shores." Similar relations are found universally to hold between the organisms which inhabit oceanic islands and those which inhabit neighbouring con- tinents. These facts of geographical distribution, when taken in connection with the facts of geologi- cal succession above mentioned, speak very em- 409 COSMIC PHILOSOPHY phatically in favour of the derivation theory. That theory affords a satisfactory explanation for this entire class of facts, while the special creation hypothesis is incompetent to explain a single one of them. They are, moreover, in perfect harmony with the prominent facts of morphology, of embryology, and of classifica- tion — so that the evidence furnished by the four classes of facts taken together becomes truly overwhelming. When in the next chapter we come to con- sider the speculations and discoveries of Mr. Darwin, we shall see that the case in favour of derivation is even stronger than as here pre- sented ; for we shall see that certain agencies are unceasingly at work, with the long continu- ance of which the absolute stability of specific forms is incompatible. But, as between the two hypotheses of special creation and of derivation, the arguments already brought forward are far more than sufficient for a decisive verdict. The presumption raised at the outset against the Doctrine of Special Creations is even super- fluously confirmed by the testimony of facts. Not only is this doctrine discredited by its bar- baric origin, and by the absurd or impossible assumptions which it would require us to make, but it utterly fails to explain a single one of the phenomena of the classification, embryo- logy, morphology, and distribution of extinct 410 SPECIAL CREATION OR DERIVATION? and living organisms. While, on the other hand, the Doctrine of Derivation is not only accredited by its scientific origin, and by its appealing to none but verifiable processes and agencies, but it affords an explanation for each and all of the above-mentioned phenomena. I think we may, therefore, without further ado, consign the special creation hypothesis to that limbo where hover the ghosts of the slaugh- tered theories that were born of man's untutored intelligence in early times. There we may let it abide, along with the vagaries of the astrolo- gists, the doctrine of signatures, the arch