The Plurality of Worlds

22. It is true, that there are other nations also, which claim an antiquity for their civilization equal to or greater than that which we can ascribe to these. Such are the Indians and the Chinese. But while we do not question that these nations were at a remote period in possession of arts, knowledge, and regular polity, in a very eminent degree, we are not at all called upon to assent to the immense numbers, tens of thousands and hundreds of thousands of years, by which such nations, in their histories, express their antiquity. For, in the first place, such numbers are easily devised and transferred to the obscure early stages of tradition, when the art of numeration is once become familiar. These vast intervals, applied to series of blank genealogies, or idle fables, gratify the popular appetite for numerical wonders, but have little claim on critical conviction.

23. And in the next place, we discover that not enumeration only, but a more recondite art, had a great share in the fabrication of these gigantic numbers of years. Some of the nations of whom we have thus spoken, the Indians, for example, had, at an early period, possessed themselves of a large share of astronomical knowledge. They had observed and examined the motions of the Sun, the Moon, the Planets, and the Stars, till they had discovered Cycles, in which, after long and seemingly irregular wanderings in the skies, the heavenly bodies came round again to known and regular positions. They had thus detected the order that reigns in the seeming disorder; and had, by this means, enabled themselves to know beforehand when certain astronomical events would occur; certain configurations of the Planets, for instance, and eclipses; and knowing how such events would occur in future, they were also able to calculate how the like events had occurred in the past. They could thus determine what eclipses and what planetary configurations had occurred, in thousands and tens of thousands of years of past time; and could, if they were disposed to falsify their early histories, and to confirm the falsification by astronomical evidence, do so with a very near approximation to astronomical truth. Such astronomical confirmation of their assertions, so incapable in any common apprehension of being derived from any other source than actual observation of the fact, naturally produced a great effect upon common minds; and still more, on those who examined the astronomical fact, enough only to see that it was, approximately, at least, true. But in recent times the fallacy of this evidence has been shown, and the fabrication detected. For though the astronomical rules which they had devised were approximately true, they were true approximately only. The more exact researches of modern European astronomy discovered that their cycles, though nearly exact, were not quite so. There was in them an error which made the cycle, at every revolution of its period, when it was applied to past ages, more and more wrong; so that the astronomical events which they asserted to have happened, as they had calculated that they would have happened, the better informed astronomer of our day knows would not have happened exactly so, but in a manner differing more and more from their statement, as the event was more and more remote. And thus the fact which they asserted to have been observed, had not really happened; and the confirmation, which it had been supposed to lend to their history, disappeared. And thus, there is not, in the asserted antiquity of Indian civilization and Indian astronomy, anything which has a well-founded claim to disturb our belief that the nations of the more western regions of Asia had a civilization as ancient as theirs. And considerations of nearly the same kind may be applied to the very remote astronomical facts which are recorded as having been observed in the history of some others of the ancient nations above mentioned.

24. Still less need we be disturbed by the long series of dynasties, each occupying a large period of years, which the Egyptians are said to have inserted in their early history, so as to carry their origin beyond the earliest times which I have mentioned. If they spoke of the Greek nations as children compared with their own long-continued age, as Plato says they did, a few thousands of years of previous existence would well entitle them to do so. So far as such a period goes, their monuments and their hieroglyphical inscriptions give a reality to their pretensions, which we may very willingly grant. And even the history of the Jews supposes that the Egyptians had attained a high point in arts, government, knowledge, when Abraham, the father of the Jewish nation, was still leading the life of a nomad. But this supposition is not inconsistent with the account which the Jewish Scriptures give, of the origin of nations; especially if, as we have said, we abstain from any rigid and narrow interpretation of the chronology of those scriptures; as on every ground, it is prudent to do.

25. It appears then not unreasonable to believe, that a very few thousands, or even a few hundreds of years before the time of Abraham, the nations of central and western Asia offer to us the oldest aspect of the life of man upon the earth; and that in reasoning concerning the antiquity of the human race, we may suppose that at that period, he was in the earliest stages of his existence. Although, in truth, if we were to accept the antiquity claimed by the Egyptians, the Indians, or the Chinese, the nature of our argument would not be materially altered; for ten thousand, or even twenty thousand years, bears a very small proportion to the periods of time which geology requires for the revolutions which she describes; and, as I have said, we have geological evidence also, to show how brief the human period has been, when compared with the period which preceded the existence of man. And if this be so; if such peoples as those who have left to us the monuments of Egypt and of Assyria, the pyramids and ancient Thebes, the walls of Nineveh and Babylon, were the first nations which lived as nations; or if they were separated from such only by the interval by which the Germans of to-day are separated from the Germans of Tacitus; we may well repeat our remark, that the history of man, in the earliest times, is as truly a history of a wonderful, intellectual, social, political, spiritual creature, as it is at present. We see, in the monuments of those periods, evidences so great and so full of skill, that even now, they amaze us, of arts, government, property, thought, the love of beauty, the recognition of deity; evidences of memory, foresight, power. If London or Berlin were now destroyed, overwhelmed, and, four thousand years hence, disinterred, these cities would not afford stronger testimony of those attributes, as existing in modern Europeans, than we have of such qualities in the ancient Babylonians and Egyptians. The history of man, as that of a creature pre-eminent in the creation, is equally such, however far back we carry our researches.

26. Nor is there anything to disturb this view, in the fact of the existence of the uncultured and barbarous tribes which occupy, and always have occupied, a large portion of the earth's surface. For, in the first place, there is not, in the aspect of the fact, or in the information which history gives us, any reason to believe that such tribes exhibit a form of human existence, which, in the natural order of progress, is earlier than the forms of civilized life, of which we have spoken. The opinion that the most savage kind of human life, least acquainted with arts, and least provided with resources, is the state of nature out of which civilized life has everywhere gradually emerged, is an opinion which, though at one time popular, is unsupported by proof, and contrary to probability.[7 - A recent popular writer, who has asserted the self-civilizing tendency of man, has not been able, it would seem, to adduce any example of the operation of this tendency, except a single tribe of North American Indians, in whom it operated for a short time, and to a small extent.] Savage tribes do not so grow into civilization; their condition is, far more probably, a condition of civilization degraded and lost, than of civilization incipient and prospective. Add to this, that if we were to assume that this were otherwise; if man thus originally and naturally savage, did also naturally tend to become civilized; this tendency is an endowment no less wonderful, than those endowments which civilization exhibits. The capacity is as extraordinary as the developed result; for the capacity involves the result. If savage man be the germ of the most highly civilized man, he differs from all other animal germs, as man differs from brute. And add to this again, that in the tribes which we call savage, and whose condition most differs, in external circumstances, from ours, there are, after all, a vast mass of human attributes: thought, purpose, language, family relations; generally property, law, government, contract, arts, and knowledge, to no small extent; and in almost every case, religion. Even uncivilized man is an intellectual, moral, social, religious creature; nor is there, in his condition, any reason why he may not be a spiritual creature, in the highest sense in which the most civilized man can be so.

27. Here then we are brought to the view which, it would seem, offers a complete reply to the difficulty, which astronomical discoveries appeared to place in the way of religion:—the difficulty of the opinion that man, occupying this speck of earth, which is but as an atom in the Universe, surrounded by millions of other globes, larger, and, to appearance, nobler than that which he inhabits, should be the object of the peculiar care and guardianship, of the favor and government, of the Creator of All, in the way in which Religion teaches us that He is. For we find that man, (the human race, from its first origin till now,) has occupied but an atom of time, as he has occupied but an atom of space:—that as he is surrounded by myriads of globes which may, like this, be the habitations of living things, so he has been preceded, on this earth, by myriads of generations of living things, not possibly or probably only, but certainly; and yet that, comparing his history with theirs, he has been, certainly has been fitted to be, the object of the care and guardianship, of the favor and government, of the Master and Governor of All, in a manner entirely different from anything which it is possible to believe with regard to the countless generations of brute creatures which had gone before him. If we will doubt or overlook the difference between man and brutes, the difficulty of ascribing to man peculiar privileges, is made as great by the revelations of geology, as of astronomy. The scale of man's insignificance is, as we have said, of the same order in reference to time, as to space. There is nothing which at all goes beyond the magnitude which observation and reasoning suggest for geological periods, in supposing that the tertiary strata occupied, in their deposition and elevation, a period as much greater than the period of human history, as the solar system is larger than the earth:—that the secondary strata were as much longer than these in their formation, as the nearest fixed star is more distant than the sun:—that the still earlier masses, call them primary, or protozoic, or what we will, did, in their production, extend through a period of time as vast, compared with the secondary period, as the most distant nebula is remoter than the nearest star. If the earth, as the habitation of man, is a speck in the midst of an infinity of space, the earth, as the habitation of man, is also a speck at the end of an infinity of time. If we are as nothing in the surrounding universe, we are as nothing in the elapsed eternity; or rather, in the elapsed organic antiquity, during which the earth has existed and been the abode of life. If man is but one small family in the midst of innumerable possible households, he is also but one small family, the successor of innumerable tribes of animals, not possible only, but actual. If the planets may be the seats of life, we know that the seas which have given birth to our mountains were the seats of life. If the stars may have hundreds of systems of tenanted planets rolling round them, we know that the secondary group of rocks does contain hundreds of tenanted beds, witnessing of as many systems of organic creation. If the nebulæ may be planetary systems in the course of formation, we know that the primary and transition rocks either show us the earth in the course of formation, as the future seat of life, or exhibit such life as already begun.

28. How far that which astronomy thus asserts as possible, is probable:—what is the value of these possibilities of life in distant regions of the universe, we shall hereafter consider. But in what geology asserts, the case is clear. It is no possibility, but a certainty. No one will now doubt that shells and skeletons, trunks and leaves, prove animal and vegetable life to have existed. Even, therefore, if Astronomy could demonstrate all that her most fanciful disciples assume, Geology would still have a complete right to claim an equal hearing;—to insist upon having her analogies regarded. She would have a right to answer the questions of Astronomy, when she says, How can we believe this? and to have her answers accepted.

29. Astronomy claims a sort of dignity over all other sciences, from her antiquity, her certainty, and the vastness of her discoveries. But the antiquity of astronomy as a science had no share in such speculations as we are discussing; and if it had had, new truths are better than old conjectures; new discoveries must rectify old errors; new answers must remove old difficulties. The vigorous youth of Geology makes her fearless of the age of Astronomy. And as to the certainty of Astronomy, it has just as little to do with these speculations. The certainty stops, just when these speculations begin. There may, indeed, be some danger of delusion on this subject. Men have been so long accustomed to look upon astronomical science as the mother of certainty, that they may confound astronomical discoveries with cosmological conjectures; though these be slightly and illogically connected with those. And then, as to the vastness of astronomical discoveries,—granting that character, inasmuch as it is to a certain degree, a matter of measurement,—we must observe, that the discoveries of geology are no less vast: they extend through time, as those of astronomy do through space. They carry us through millions of years, that is, of the earth's revolutions, as those of astronomy do through millions of the earth's diameters, or of diameters of the earth's orbit. Geology fills the regions of duration with events, as astronomy fills the regions of the universe with objects. She carries us backwards by the relation of cause and effect, as astronomy carries us upwards by the relations of geometry. As astronomy steps on from point to point of the universe by a chain of triangles, so geology steps from epoch to epoch of the earth's history by a chain of mechanical and organical laws. If the one depends on the axioms of geometry, the other depends on the axioms of causation.

30. So far then, Geology has no need to regard Astronomy as her superior; and least of all, when they apply themselves together to speculations like these. But in truth, in such speculations, Geology has an immeasurable superiority. She has the command of an implement, in addition to all that Astronomy can use; and one, for the purpose of such speculations, adapted far beyond any astronomical element of discovery. She has, for one of her studies,—one of her means of dealing with her problems,—the knowledge of Life, animal and vegetable. Vital organization is a subject of attention which has, in modern times, been forced upon her. It is now one of the main parts of her discipline. The geologist must study the traces of life in every form; must learn to decypher its faintest indications and its fullest development. On the question, then, whether there be in this or that quarter, evidence of life, he can speak with the confidence derived from familiar knowledge; while the astronomer, to whom such studies are utterly foreign, because he has no facts which bear upon them, can offer, on such questions, only the loosest and most arbitrary conjectures; which, as we have had to remark, have been rebuked by eminent men, as being altogether inconsistent with the acknowledged maxims of his science.

31. When, therefore, Geology tells us that the earth, which has been the seat of human life for a few thousand years only, has been the seat of animal life for myriads, it may be, millions of years, she has a right to offer this, as an answer to any difficulty which Astronomy, or the readers of astronomical books, may suggest, derived from the considerations that the Earth, the seat of human life, is but one globe of a few thousand miles in diameter, among millions of other globes, at distances millions of times as great.

32. Let the difficulty be put in any way the objector pleases. Is it that it is unworthy of the greatness and majesty of God, according to our conceptions of Him, to bestow such peculiar care on so small a part of His creation? But we know, from geology, that He has bestowed upon this small part of His creation, mankind, this special care;—He has made their period, though only a moment in the ages of animal life, the only period of intelligence, morality, religion. If then, to suppose that He has done this, is contrary to our conceptions of His greatness and majesty, it is plain that our conceptions are erroneous; they have taken a wrong direction. God has not judged, as to what is worthy of Him, as we have judged. He has found it worthy of Him to bestow upon man His special care, though he occupies so small a portion of time; and why not, then, although he occupies so small a portion of space?

33. Or is the objection this; that if we suppose the earth only to be occupied by inhabitants, all the other globes of the universe are wasted;—turned to no purpose? Is waste of this kind considered as unsuited to the character of the Creator? But here again, we have the like waste, in the occupation of the earth. All its previous ages, its seas and its continents, have been wasted upon mere brute life; often, so far as we can see, for myriads of years, upon the lowest, the least conscious forms of life; upon shell-fish, corals, sponges. Why then should not the seas and continents of other planets be occupied at present with a life no higher than this, or with no life at all? Will it be said that, so far as material objects are occupied by life, they are not wasted; but that they are wasted, if they are entirely barren and blank of life? This is a very arbitrary saying. Why should the life of a sponge, or a coral, or an oyster, be regarded as a good employment of a spot of land and water, so as to save it from being wasted? No doubt, if the coral or the oyster be there, there is a reason why it is so, consistently with the attributes of God. But then, on the same ground, we may say that if it be not there, there is a reason why it is not so. Such a mode of regarding the parts of the universe can never give us reasons why they should or should not be inhabited, when we have no other grounds for knowing whether they are. If it be a sufficient employment of a spot of rock or water that it is the seat of organization—of organic powers; why may it not be a sufficient employment of the same spot that it is the seat of attraction, of cohesion, of crystalline powers? All the planets, all parts of the universe, we have good reason to believe, are pervaded by attraction, by forces of aggregation and atomic relation, by light and heat. Why may not these be sufficient to prevent the space being wasted, in the eyes of the Creator? as, during a great part of the earth's past history, and over large portions of its present mass, they are actually held by Him sufficient; for they are all that occupy those portions. This notion, then, of the improbability of there being, in the universe, so vast an amount of waste spaces, or waste bodies, as is implied in the opinion that the earth alone is the seat of life, or of intelligence, is confuted by the fact, that there are vast spaces, waste districts, and especially waste times, to an extent as great as such a notion deems improbable. The avoidance of such waste, according to our notions of waste, is no part of the economy of creation, so far as we can discern that economy, in its most certain exemplifications.

34. Or will the objection be made in this way; that such a peculiar dignity and importance given to the earth is contrary to the analogy of creation;—that since there are so many globes, similar to the earth,—like her, revolving round the sun, like her, revolving on her axes, several of them, like her, accompanied by satellites; it is reasonable to suppose that their destination and office is the same as hers;—that since there are so many stars, each like the sun, a source of light, and probably of heat, it is reasonable to suppose that, like the sun, they are the centres of systems of planets, to which their light and heat are imparted, to uphold life:—is it thought that such a resemblance is a strong ground for believing that the planets of our system, and of other systems, are inhabited as the earth is? If such an astronomical analogy be insisted on, we must again have recourse to geology, to see what such analogy is worth. And then, we are led to reflect, that if we were to follow such analogies, we should be led to suppose that all the successive periods of the earth's history were occupied with life of the same order; that as the earth, in its present condition, is the seat of an intelligent population, so must it have been, in all former conditions. The earth, in its former conditions, was able and fitted to support life; even the life of creatures closely resembling man in their bodily structure. Even of monkeys, fossil remains have been found. But yet, in those former conditions, it did not support human life. Even those geologists who have dwelt most on the discovery of fossil monkeys, and other animals nearest to man, have not dreamt that there existed, before man, a race of rational, intelligent, and progressive creatures. As we have seen, geology and history alike refute such a fancy. The notion, then, that one period of time in the history of the earth must resemble another, in the character of its population, because it resembles it in physical circumstances, is negatived by the facts which we discover in the history of the earth. And so, the notion that one part of the universe must resemble another in its population, because it resembles it in physical circumstances, is negatived as a law of creation. Analogy, further examined, affords no support to such a notion. The analogy of time, the events of which we know, corrects all such guesses founded on a supposed analogy of space, the furniture of which, so far as this point is concerned, we have no sufficient means of examining.

35. But in truth, we may go further. Not only does the analogy of creation not point to any such entire resemblance of similar parts, as is thus assumed, but it points in the opposite direction. Not entire resemblance, but universal difference is what we discover; not the repetition of exactly similar cases, but a series of cases perpetually dissimilar, presents itself; not constancy, but change, perhaps advance; not one permanent and pervading scheme, but preparation and completion of successive schemes; not uniformity and a fixed type of existences, but progression and a climax. This may be said to be the case in the geological aspect of the world; for, without occupying ourselves with the question, how far the monuments of animal life, which we find preserved in the earth's strata, exhibited a gradual progression from ruder and more imperfect forms to the types of the present terrestrial population; from sponges and mollusks, to fish and lizards, from cold-blooded to warm blooded animals, and so on, till we come to the most perfect vertebrates;—a doctrine which many eminent geologists have held, and still hold;—without discussing this question, or assuming that the fact is so; this at least cannot be denied or doubted, that man is incomparably the most perfect and highly-endowed creature which ever has existed on the earth. How far previous periods of animal existence were a necessary preparation of the earth, as the habitation of man, or a gradual progression towards the existence of man, we need not now inquire. But this at least we may say; that man, now that he is here, forms a climax to all that has preceded; a term incomparably exceeding in value all the previous parts of the series; a complex and ornate capital to the subjacent column; a personage of vastly greater dignity and importance than all the preceding line of the procession. The analogy of nature, in this case at least, appears to be, that there should be inferior, as well as superior provinces, in the universe; and that the inferior may occupy an immensely larger portion of time than the superior; why not then of space? The intelligent part of creation is thrust into the compass of a few years, in the course of myriads of ages; why not then into the compass of a few miles, in the expanse of systems? The earth was brute and inert, compared with its present condition, dark and chaotic, so far as the light of reason and intelligence are concerned, for countless centuries before man was created. Why then may not other parts of creation be still in this brute and inert and chaotic state, while the earth is under the influence of a higher exercise of creative power? If the earth was, for ages, a turbid abyss of lava and of mud, why may not Mars or Saturn be so still? If the germs of life were, gradually, and at long intervals, inserted in the terrestrial slime, why may they not be just inserted, or not yet inserted, in Jupiter? Or why should we assume that the condition of those planets resembles ours, even so far as such suppositions imply? Why may they not, some or all of them, be barren masses of stone and metal, slag and scoriæ, dust and cinders? That some of them are composed of such materials, we have better reason to believe, than we have to believe anything else respecting their physical constitution, as we shall hereafter endeavor to show. If then, the earth be the sole inhabited spot in the work of creation, the oasis in the desert of our system, there is nothing in this contrary to the analogy of creation. But if, in some way which perhaps we cannot discover, the earth obtained, for accompaniments, mere chaotic and barren masses, as conditions of coming into its present state; as it may have required, for accompaniments, the brute and imperfect races of former animals, as conditions of coming into its present state, as the habitation of man; the analogy is against, and not in favor of, the belief that they too (the other masses, the planets, &c.) are habitations. I may hereafter dwell more fully on such speculations; but the possibility that the planets are such rude masses, is quite as tenable, on astronomical grounds, as the possibility that the planets resemble the earth, in matters of which astronomy can tell us nothing. We say, therefore, that the example of geology refutes the argument drawn from the supposed analogy of one part of the universe with another; and suggests a strong suspicion that the force of analogy, better known, may tend in the opposite direction.

36. When such possibilities are presented to the reader, he may naturally ask, if we are thus to regard man as the climax of creation, in space, as in time, can we point out any characters belonging to him, which may tend to make it conceivable that the Creator should thus distinguish him, and care for him:—should prepare his habitation if it be so, by ages of chaotic and rudimentary life, and by accompanying orbs of brute and barren matter. If Man be, thus, the head, the crowned head of the creation, is he worthy to be thus elevated? Has he any qualities which make it conceivable that, with such an array of preparation and accompaniment, he should be placed upon the earth, his throne? Or rather, if he be thus the chosen subject of God's care, has he any qualities, which make it conceivable that he should be thus selected; taken under such guardianship; admitted to such a dispensation; graced with such favor. The question with which we began again recurs: What is man that God should be thus mindful of him? After the views which have been presented to us, does any answer now occur to us?

37. The answer which we have to give, is that which we have already repeatedly stated. Man is an intellectual, moral, religious, and spiritual creature. If we consider these attributes, we shall see that they are such as to give him a special relation to God, and as we conceive, and must conceive, God to be; and may therefore be, in God, the occasion of special guardianship, special regard, a special dispensation towards man.

38. As an intellectual creature, he has not only an intelligence which he can apply to practical uses, to minister to the needs of animal and social life; but also an intellect by which he can speculate about the relations of things, in their most general form; for instance, the properties of space and time, the relations of finite and infinite. He can discover truths, to which all things, existing in space and time, must conform. These are conditions of existence to which the creation conforms, that is, to which the Creator conforms; and man, capable of seeing that such conditions are true and necessary, is capable, so far, of understanding some of the conditions of the Creator's workmanship. In this way, the mind of man has some community with the mind of God; and however remote and imperfect this community may be, it must be real. Since, then, man has thus, in his intellect, an element of community with God, it is so far conceivable that he should be, in a special manner, the object of God's care and favor. The human mind, with its wonderful and perhaps illimitable powers, is something of which we can believe God to be "mindful."

39. Again: man is a moral creature. He recognizes, he cannot help recognizing, a distinction of right and wrong in his actions; and in his internal movements which lead to action. This distinction he recognizes as the reason, the highest and ultimate reason, for doing or for not doing. And this law of his own reason, he is, by reflection, led to recognize as a Law of the Supreme Reason; of the Supreme Mind which has made him what he is. The Moral Law, he owns and feels as God's Law. By the obligation which he feels to obey this Law, he feels himself God's subject; placed under his government; compelled to expect his judgment, his rewards, and punishments. By being a moral creature, then, he is, in a special manner, the subject of God; and not only we can believe that, in this capacity, God cares for him; but we cannot believe that he does not care for him. He cares for him, so as to approve of what he does right, and to condemn what he does wrong. And he has given him, in his own breast, an assurance that he will do this; and thus, God cares for man, in a peculiar and special manner. As a moral creature, we have no difficulty in conceiving that God may think him worthy of his regard and government.

40. The development of man's moral nature, as we have just described it, leads to, and involves the development of his religious nature. By looking within himself, and seeing the Moral Law, he learns to look upwards to God, the Author of the Law, and the Awarder of the rewards and penalties which follow moral good and evil. But the belief of such a dispensation carries us, or makes us long to be carried, beyond the manifestations of this dispensation, as they appear in the ordinary course of human life. By thinking on such things, man is led to ascribe a wider range to the moral Government of God:—to believe in methods of reward and punishment, which do not appear in the natural course of events: to accept events, out of the order of nature, which announce that God has provided such methods: to accept them, when duly authenticated, as messages from God; and thus, when God provides the means, to allow himself to be placed in intercourse with God. Since man is capable of this; since, as a religious creature, this is his tendency, his need, the craving of his heart, without which, when his religious nature is fully unfolded, he can feel no comfort nor satisfaction; we cannot be surprised that God should deem him a proper object of a special fatherly care; a fit subject for a special dispensation of his purposes, as to the consequences of human actions. Man being this, we can believe that God is not only "mindful of him," but "visits him."

41. As we have said, the soul of man, regarded as the subject of God's religious government, is especially termed his Spirit: the course of human being which results from the intercourse with God, which God permits, is a spiritual existence. Man is capable, in no small degree, of such an existence, of such an intercourse with God; and, as we are authorized to term it, of such a life with God, and in God, even while he continues in his present human existence. I say authorized, because such expressions are used, though reverently, by the most religious men; who are, at any rate, authority as to their own sentiments; which are the basis of our reasoning. Whatever, then, may be the imperfection, in this life, of such a union with God, yet since man can, when sufficiently assisted and favored by God, enter upon such a union, we cannot but think it most credible and most natural, that he should be the object of God's special care and regard, even of his love and presence.

42. That men are, only in a comparatively small number of cases, intellectual, moral, religious, and spiritual, in the degree which I have described, does not, by any means, deprive our argument of its force. The capacity of man is, that he may become this; and such a capacity may well make him a special object in the eyes of Him under whose guidance and by whose aid, such a development and elevation of his nature is open to him. However imperfect and degraded, however unintellectual, immoral, irreligious, and unspiritual, a great part of mankind may be, still they all have the germs of such an elevation of their nature; and a large portion of them make, we cannot doubt, no small progress in this career of advancement to a spiritual condition. And with such capacities, and such practical exercise of those capacities, we can have no difficulty in believing, if the evidence directs us to believe, that that part of the creation in which man has his present appointed place, is the special field of God's care and love; by whatever wastes of space, and multitudes of material bodies, it may be surrounded; by whatever races it may have been previously occupied, of brutes that perish, and that, compared with man, can hardly be said to have lived.

CHAPTER VII

THE NEBULÆ

1. I have attempted to show that, even if we suppose the other bodies of the universe to resemble the Earth, so far as to seem, by their materials, forms, and motions, no less fitted than she is to be the abodes of life; yet that, knowing what we do of man, we can believe that the Earth is tenanted by a race who are the special objects of God's care. Even if the tendency of the analogies of creation were, to incline us to suppose that the other planets are as well suited as our globe, to have inhabitants, still it would require a great amount of evidence, to make us believe that they have such inhabitants as we are; while yet such evidence is altogether wanting. Even if we knew that the stars were the centres of revolving systems, we should have an immense difficulty in believing that an Earth, with such a population as ours, revolves about any of them. If astronomy made a plurality of worlds probable, we have strong reasonings, drawn from other subjects, to think that the other worlds are not like ours.

2. The admirers of astronomical triumphs may perhaps be disposed to say, that when so much has been discovered, we may be allowed to complete the scheme by the exercise of fancy. I have attempted to show that we are not in such a state of ignorance, when we look at other relations of the earth and of man, as to allow us to do this. But now we may go a little onwards in our argument; and may ask, whether Astronomy really does what is here claimed for her:—whether she carries us so securely to the bounds of the visible universe, that our Fancy may take up the task, and people the space thus explored:—whether the bodies which Astronomy has examined, be really as fitted as our Earth, to sustain a population of living things:—whether the most distant objects in the universe do really seem to be systems, or the beginnings of systems:—whether Astronomy herself may not incline in favor of the condition of man, as being the sole creature of his kind?

3. In making this inquiry, it will of course be understood, that I do so with the highest admiration for the vast discoveries which Astronomy has really made; and for the marvellous skill and invention of the great men who have, in all ages of the world, and not least, in our time, been the authors of such discoveries. From the time when Galileo first discovered the system of Jupiter's satellites, to the last scrutiny of the structure of a nebula by Lord Rosse's gigantic telescope, the history of the telescopic exploration of the sky, has been a history of genius felicitously employed in revealing wonders. In this history, the noble labors of the first and the second Herschel relative to the distribution of the fixed stars, the forms and classes of nebulæ, and the phenomena of double stars, especially bear upon our present speculations; to which we may add, the examination of the aspect of each planet, by various observers, as Schroeter, and of the moon by others, from Huyghens to Mädler and Beer. The achievements which are most likely to occur to the reader's mind are those of the Earl of Rosse; as being the latest addition to our knowledge, and the result of the greatest instrumental powers. By the energy and ingenuity of that eminent person, an eye is directed to the heavens, having a pupil of six feet diameter, with the most complete optical structure, and the power of ranging about for its objects over a great extent of sky; and thus the quantity of light which the eye receives from any point of the heavens is augmented, it may be, fifty thousand times. The rising Moon is seen from the Observatory in Ireland with the same increase of size and light, as if her solid globe, two thousand miles in diameter, retaining all its illumination, really rested upon the summits of the Alps, to be gazed at by the naked eye. An object which appears to the naked eye a single star, may, by this telescope, so far as its power of seeing is concerned, be resolved into fifty thousand stars, each of the same brightness as the obvious star. What seems to the unassisted vision a nebula, a patch of diluted light, in which no distinct luminous point can be detected, may, by such an instrument, be discriminated or resolved into a number of bright dots; as the stippled shades of an engraving are resolved into dots by the application of a powerful magnifying glass. Similar results of the application of great telescopic power had of course been attained long previously; but, as the nature of scientific research is, each step adds something to our means of knowledge; and the last addition assumes, includes, and augments the knowledge which we possessed before. The discussions in which we are engaged, belong to the very boundary region of science;—to the frontier where knowledge, at least astronomical knowledge, ends, and ignorance begins. Such discoveries, therefore, as those made by Lord Rosse's telescope, require our special notice here.

4. We may begin, at what appears to us the outskirts of creation, the Nebulæ. At one time it was conceived by astronomers in general, that these patches of diffused light, which are seen by them in such profusion in the sky, are not luminous bodies of regular terms and definite boundaries, apparently solid, as the stars are supposed to be; but really, as even to good telescopes many of them seem, masses of luminous cloud or vapor, loosely held together, as clouds and vapors are, and not capable by any powers of vision of being resolved into distinct visible elements. This opinion was for a time so confidentially entertained, that there was founded upon it an hypothesis, that these were gaseous masses, out of which suns and systems might afterwards be formed, by the concentration of these luminous vapors into a solid central sun, more intensely luminous; while detached portions of the mass, flying off, and cooling down so as to be no longer self-luminous, might revolve round the central body, as planets and satellites. This is the Nebular Hypothesis, suggested by the elder Herschel, and adopted by the great mathematician Laplace.

5. But the result of the optical scrutiny of the nebulæ by more modern observers, especially by Lord Rosse in Ireland, and Mr. Bond in America, has been, that many celestial objects which were regarded before as truly nebulous, have been resolved into stars; and this resolution has been extended to so many cases of nebulæ, of such various kinds, as to have produced a strong suspicion in the minds of astronomers that all the nebulæ, however different in their appearance, may really be resolved into stars, if they be attacked with optical powers sufficiently great.

6. If this were to be assumed as done, and if each of the separate points, into which the nebulæ are thus resolved, were conceived to be a star, which looks so small only because it is so distant, and which really is as likely to have a system of planets revolving about it, as is a star of the first magnitude:—we should then have a view of the immensity of the visible universe, such as I presented to the reader in the beginning of this essay. All the distant nebulæ appear as nebulæ, only because they are so distant; if truly seen, they are groups of stars, of which each may be as important as our sun, being, like it, the centre of a planetary system. And thus, a patch of the heavens, one hundredth or one thousandth part of the visible breadth of our sun, may contain in it more life, not only than exists in the solar system, but in as many such systems as the unassisted eye can see stars in the heavens, on the clearest winter night.

7. This is a stupendous view of the greatness of the creation; and, to many persons, its very majesty, derived from magnitude and number, will make it so striking and acceptable, that, once apprehended, they will feel as if there were a kind of irreverence in disturbing it. But if this view be really not tenable when more closely examined, it is, after all, not wise to connect our feelings of religious reverence with it, so that they shall suffer a shock when we are obliged to reject it. I may add, that we may entertain an undoubting trust that any view of the creation which is found to be true, will also be found to supply material for reverential contemplation. I venture to hope that we may, by further examination, be led to a reverence of a deeper and more solemn character than a mere wonder at the immensity of space and number.

8. But whatever the result may be, let us consider the evidence for this view. It assumes that all the Nebulæ are resolvable into stars, and that they appear as nebulæ only because they are more distant than the region in which they can appear as stars. Are there any facts, any phenomena in the heavens, which may help us to determine whether this is a probable opinion?

9. It is most satisfactory for us, when we can, in such inquiries, know the thoughts which have suggested themselves to the minds of those who have examined the phenomena with the most complete knowledge, the greatest care, and the best advantages; and have speculated upon these phenomena in a way both profound and unprejudiced. Some remarks of Sir John Herschel, recommended by these precious characters, seem to me to bear strongly upon the question which I have just had to ask:—Do all the nebulæ owe their nebulous appearance to their being too distant to be seen as groups of distinct stars, though they really are such groups?

10. Herschel, in the visit which he made to the Cape of Good Hope, for the purpose of erecting to his father the most splendid monument that son ever erected,—the completed survey of the vault of heaven,—had full opportunity of studying a certain pair of remarkable bright spaces of the skies, filled with a cloudy light, which lie near the southern pole; and which, having been unavoidably noticed by the first Antarctic voyagers, are called the Magellanic Clouds. When the larger of these two clouds is examined through powerful telescopes, it presents, we are told, a constitution of uncommon complexity: "large patches and tracts of nebulosity in every stage of resolution, from light, irresolvable with eighteen inches of reflecting aperture, up to perfectly separated stars like the Milky Way, and clustering groups sufficiently insulated and condensed to come under the designation of irregular, and in some cases pretty rich clusters. But besides these, there are also nebulæ in abundance, both regular and irregular; globular clusters in every stage of condensation, and objects of a nebulous character quite peculiar, and which have no analogies in any other region of the heavens."[8 - Herschel, Outl. of Astr. Art. 893.] He goes on to say, that these nebulæ and clusters are far more crowded in this space than they are in any other, even the most crowded parts, of the nebulous heavens. This Nubecula Major, as it is termed, is of a round or oval form, and its diameter is about six degrees, so that it is about twelve times the apparent diameter of the moon. The Nubecula Minor is a smaller patch of the same kind. If we suppose the space occupied by the various objects which the nubecula major includes, to be, in a general way, spherical, its nearest and most remote parts must (as its angular size proves) differ in their distance from us by little more than a tenth part of our distance from its centre. That the two nubeculæ are thus approximately spherical spaces, is in the highest degree probable; not only from the peculiarity of their contents, which suggests the notion of a peculiar group of objects, collected into a limited space; but from the barrenness, as to such objects, of the sky in the neighborhood of these Magellanic Clouds. To suppose (the only other possible supposition) that they are two columns of space, with their ends turned towards us, and their lengths hundreds and thousands of times their breadths, would be too fantastical a proceeding to be tolerated; and would, after all, not explain the facts without further altogether arbitrary assumptions.

11. It appears, then, that, in these groups, there are stars of various magnitudes, clusters of various forms, nebulæ regular and irregular, nebulous tracts and patches of peculiar character; and all so disposed, that the most distant of them, whichever these may be, are not more than one-tenth more distant than the nearest. If the nearest star in this space be at nine times the distance of Sirius, the farthest nebulæ, contained in the same space, will not be at more than ten times the distance of Sirius. Of course, the doctrine that nebulæ are seen as nebulæ, merely because they are so distant, requires us to assume all nebulæ to be hundreds and thousands of times more distant than the smallest stars. If stars of the eighth magnitude (which are hardly visible to the naked eye) be eight times as remote as Sirius, a nebula containing a thousand stars, which is invisible to the naked eye, must be more than eight thousand times as remote as Sirius. And thus if, in the whole galaxy, we reckon only the stars as far as the eighth magnitude, and suppose all the stars of the galaxy to form a nebula, which is visible to the spectators in a distant nebula, only as their nebula is visible to us; we must place them at eight thousand times two hundred thousand times the distance of the Sun; and, even so, we are obviously vastly understating the calculation. These are the gigantic estimates with which some astronomical speculators have been in the habit of overwhelming the minds of their listeners; and these views have given a kind of majesty to the aspect of the nebulæ; and have led some persons to speak of the discovery of every new streak of nebulous light in the starry heavens, as a discovery of new worlds, and still new worlds. But the Magellanic Clouds show us very clearly that all these calculations are entirely baseless. In those regions of space, there coexists, in a limited compass, and in indiscriminate position, stars, clusters of stars, nebulæ, regular and irregular, and nebulous streaks and patches. These, then, are different kinds of things in themselves, not merely different to us. There are such things as nebulæ side by side with stars, and with clusters of stars. Nebulous matter resolvable occurs close to nebulous matter irresolvable. The last and widest step by which the dimensions of the universe have been expanded in the notions of eager speculators, is checked by a completer knowledge and a sager spirit of speculation. Whatever inference we may draw from the resolvability of some of the nebulæ, we may not draw this inference;—that they are more distant, and contain a larger array of systems and of worlds, in proportion as they are difficult to resolve.

12. But indeed, if we consider this process, of the resolution of nebulæ into luminous points, on its own ground, without looking to such facts as I have just adduced, it will be difficult, or impossible, to assign any reason why it should lead to such inferences as have been drawn from it. Let us look at this matter more clearly. An astronomer, armed with a powerful telescope, resolves a nebula, discerns that a luminous cloud is composed of shining dots:—but what are these dots? Into what does he resolve the nebula? Into Stars, it is commonly said. Let us not wrangle about words. By all means let these dots be Stars, if we know about what we are speaking: if a Star merely mean a luminous dot in the sky. But that these stars shall resemble, in their nature, stars of the first magnitude, and that such stars shall resemble our Sun, are surely very bold structures of assumption to build on such a basis. Some nebulæ are resolvable; are resolvable into distinct points; certainly a very curious, probably an important discovery. We may hereafter learn that all nebulæ are resolvable into distinct points: that would be a still more curious discovery. But what would it amount to? What would be the simple way of expressing it, without hypothesis, and without assumption? Plainly this: that the substance of all nebulæ is not continuous, but discrete;—separable, and separate into distinct luminous elements;—nebulæ are, it would then seem, as it were, of a curdled or granulated texture; they have run into lumps of light, or have been formed originally of such lumps. Highly curious. But what are these lumps? How large are they? At what distances? Of what structure? Of what use? It would seem that he must be a bold man who undertakes to answer these questions. Certainly he must appear to ordinary thinkers to be very bold, who, in reply, says, gravely and confidently, as if he had unquestionable authority for his teaching:—"These lumps, O man, are Suns; they are distant from each other as far as the Dog-star is from us; each has its system of Planets, which revolve around it; and each of these Planets is the seat of an animal and vegetable creation. Among these Planets, some, we do not yet know how many, are occupied by rational and responsible creatures, like Man; and the only matter which perplexes us, holding this belief on astronomical grounds, is, that we do not quite see how to put our theology into its due place and form in our system."

13. In discussing such matters as these, where our knowledge and our ignorance are so curiously blended together, and where it is so difficult to make men feel that so much ignorance can lie so close to so much knowledge;—to make them believe that they have been allowed to discover so much, and yet are not allowed to discover more:—we may be permitted to illustrate our meaning, by supposing a case of blended knowledge and ignorance, of real and imaginary discovery. Suppose that there were carried from a scientific to a more ignorant nation, excellent maps of the world, finely engraved; the mountain-ranges shaded in the most delicate manner, and the sheet crowded with information of all kinds, in writing large, small, and microscopic. Suppose also, that when these maps had been studied with the naked eye, so as to establish a profound respect for the knowledge and skill of the author of them, some of those who perused them should be furnished with good microscopes, so as to carry their examination further than before. They might then find that, in several parts, what before appeared to be merely crooked lines, was really writing, stating, it may be, the amount of population of a province, or the date of foundation of a town. To exhaust all the information thus contained on the maps, might be a work of considerable time and labor. But suppose that, when this was done, a body of resolute microscopists should insist that the information which the map contained was not exhausted: that they should continue peering perseveringly at the lines which formed the shading of the mountains, maintaining that these lines also were writing, if only it might be deciphered; and should go on increasing, with immense labor and ingenuity, the powers of their microscopes, in order to discover the legend contained in these unmeaning lines. We should, perhaps, have here an image of the employment of these astronomers, who now go on looking in nebulæ for worlds. And we may notice in passing, that several of the arguments which are used by such astronomers, might be used, and would be used, by our microscopists:—how improbable it was that a person so full of knowledge, and so able to convey it, as the author of the maps was known to be, should not have a design and purpose in every line that he drew: what a waste of space it would be to leave any part of the sheet blank of information; and the like. To which the reply is to us obvious; that the design of shading the mountains was design enough; and that the information conveyed was all that was necessary or convenient. Nor does this illustration at all tend to show that such astronomical scrutiny, directed intelligently, with a right selection of the points examined, may not be highly interesting and important. If the microscopists had examined the map with a view to determine the best way in which mountains can be indicated by shading, they would have employed themselves upon a question which has been the subject of multiplied and instructive discussion in our own day.

14. But to return to the subject of Nebulæ, we may further say, with the most complete confidence, that whether or not nebulous matter be generally resolvable into shining dots, it cannot possibly be true that its being, or not being so resolvable by our telescopes, depends merely upon its smaller or greater distance from the observer. For, in the first place, that there is matter, to the best assisted eye not distinguishable from nebulous matter, which is not so resolvable, is proved by several facts. The tails of Comets often resemble nebulæ; so much so that there are several known nebulæ, which are, by the less experienced explorers of the sky, perpetually mistaken for comets, till they are proved not to be so, by their having no cometary motion. Such is the nebula in Andromeda, which is visible to the naked eye.[9 - Herschel, Outl. of Astr. Art. 874, and Plate 11, Fig. 3.] But the tails and nebulous appendages of comets, though they alter their appearance very greatly, according to the power of the telescope with which they are examined, have never been resolved into stars, or any kind of dots; and seem, by all investigations, to be sheets or cylinders or cones of luminous vapor, changing their form as they approach to or recede from the sun, and perhaps by the influence of other causes. Yet some of them approach very near the earth; all of them come within the limits of our system. Here, then, we have (probably, at least,) nebulous matter, which when brought close to the eye, compared with the stellar nebulæ, still appears as nebulous.

15. Again, as another phenomenon, bearing upon the same question, we have the Zodiacal Light. This is a faint cone of light[10 - Ibid. Art. 897.] which, at certain seasons, may be seen extending from the horizon obliquely upwards, and following the course of the ecliptic, or rather, of the sun's equator. It appears to be a lens-shaped envelope of the sun, extending beyond the orbits of Mercury and Venus, and nearly attaining that of the earth; and in Sir John Herschel's view, may be regarded as placing the sun in the list of nebulous stars. No one has ever thought that this nebulous appearance was resolvable into luminous points; but if it were, probably not even the most sanguine of speculators on the multitude of suns would call these points suns.

16. But indeed the nebulæ themselves, and especially the most remote of the nebulæ, or at least those which most especially require the most powerful telescopes, offer far more decisive proofs that their resolvability or non-resolvability,—their apparent constitution as diffused and vaporous masses,—does not depend upon their distance. A remarkable fact in the irregular, and in some of the regular nebulæ[11 - Hersch. 874.] is, that they consist of long patches and streaks, which stretch out in various directions, and of which the form[12 - Ibid. 881-8.] and extent vary according to the visual power which is applied to them. Many of the nebulæ and especially of the fainter ones, entirely change their form with the optical power of the instrument by which they are scrutinized; so that, as seen in the mightier telescopes of modern times, the astronomer scarcely recognizes the figures in which the earlier observers have recorded what they saw in the same place. Parts which, before, were separate, are connected by thin bridges of light which are now detected; and where the nebulous space appeared to be bounded, it sends off long tails of faint light into the surrounding space. Now, no one can suppose that these newly-seen portions of the nebula are immensely further off than the other parts. However little we know of the nature of the object, we must suppose it to be one connected object, with all its parts, as to sense, at the same distance from us. Whether therefore it be resolvable or no, there must be some other reason, besides the difference of distance, why the brighter parts were seen, while the fainter parts were not. The obvious reason is, that the latter were not seen because they were thin films which required more light to see them. We are led, irresistibly as it seems, to regard the whole mass of such a nebula, as an aggregation of vaporous rolls and streaks, assuming such forms as thin volumes of smoke or vapor often assume in our atmosphere, and assuming, like them, different shapes according to the quantity of light which comes to us from them. If, as soon as one of these new filaments or webs of a nebula comes into view, we should say, Here we have a new array of suns and of worlds, we should judge as fantastically, as any one who should combine the like imaginations with the varying cloud-work of a summer-sky. To suppose that all the varied streaks by which the patch of nebulous light shades off into the surrounding darkness, and which change their form and extent with every additional polish which we can give to a reflecting or refracting surface, disclose, with every new streak, new worlds, is a wanton indulgence of fancy, to which astronomy gives us no countenance.[13 - At the recent meeting of the British Association (Sept. 1853), drawings were exhibited of the same nebulæ, as seen through Lord Rosse's large telescope, and through a telescope of three feet aperture. With the smaller telescopic power, all the characteristic features were lost. The spiral structure (see next Article but one) has been almost entirely brought to light by the large telescope.]

17. Undoubtedly all true astronomers, taught caution and temperance of thought by the discipline of their magnificent science, abstain from founding such assumptions upon their discoveries. They know how necessary it is to be upon their guard against the tricks which fancy plays with the senses; and if they see appearances of which they cannot interpret the meaning, they are content that they should have no meaning for them, till the due explanation comes. We have innumerable examples of this wise and cautious temper, in all periods of astronomy. One has occurred lately. Several careful astronomers, observing the stars by day, had been surprised to see globes of light glide across the field of view of their telescopes, often in rapid succession and in great numbers. They did not, as may be supposed, rush to the assumption that these globes were celestial bodies of a new kind, before unseen; and that from the peculiarity of their appearance and movement, they were probably inhabited by beings of a peculiar kind. They proceeded very differently; they altered the focus of their telescopes, looked with other glasses, made various changes and trials, and finally discovered that these globes of light were the winged seeds of certain plants which were wafted through the air; and which, illuminated by the sun, were made globular by being at distances unsuited to the focus of the telescope.[14 - See monthly Notices of the Royal Astronomical Society, Dec. 13, 1850.]

18. But perhaps something more may be founded on the ramified and straggling form which belongs to many of the nebulæ. Under the powers of Lord Rosse's telescope, a considerable number of them assume a shape consisting of several spiral films diverging from one centre, and growing broader and fainter as they diverge, so as to resemble a curled feather, or whirlpool of light.[15 - The frontispiece (#x1_x_1_i16) to this volume represents two of these Spiral Nebulæ; those denominated 51 Messier, and 99 Messier, as given by Lord Rosse in the Phil. Trans. for 1850. The former of these two has a lateral focus, besides the principal focus or pole.] This form, though generally deformed by irregularities, more or less, is traceable in so many of the nebulæ, that we cannot easily divest ourselves of the persuasion that there is some general reason for such a form;—that something, in the mechanical causes which have produced the nebulæ, has tended to give them this shape. Now, when this thought has occurred to us, since mathematicians have written a great deal concerning the mechanics of the universe, it is natural to ask, whether any of the problems which they have solved give a result like that thus presented to our eyes. Do such spirals as we here see, occur in any of the diagrams which illustrate the possible motions of celestial bodies? And to this, a person acquainted with mathematical literature might reply, that in the second Book of Newton's Principia, in the part which has especial reference to the Vortices of Descartes, such spirals appear upon the page. They represent the path which a body would describe if, acted upon by a central force, it had to move in a medium of which the resistance was considerable;—considerable, that is, in comparison with the other forces which act; as for example, the forces which deflect the motion from a straight line. Indeed, that in such a case a body would describe a spiral, of which the general form would be more or less oval, is evident on a little consideration. And in this way, for instance, Encke's comet, which, if the resistance to its motion were insensible, would go on describing an ellipse about the sun, always returning upon the same path after every revolution; does really describe a path which, at each revolution, falls a little within the preceding revolution, and thus gradually converges to the centre. And if we suppose the comet to consist of a luminous mass, or a string of masses, which should occupy a considerable arc of such an orbit, the orbit would be marked by a track of light, as an oval spiral. Or if such a comet were to separate into two portions, as we have, with our own eyes, recently seen Biela's comet do; or into a greater number; then these portions would be distributed along such a spiral. And if we suppose a large mass of cometic matter thus to move in a highly resisting medium, and to consist of patches of different densities, then some would move faster and some more slowly; but all, in spirals such as have been spoken of; and the general aspect produced would be, that of the spiral nebulæ which I have endeavored to describe. The luminous matter would be more diffused in the outer and more condensed in the central parts, because to the centre of attraction all the spirals converge.

19. This would be so, we say, if the luminous matter moved in a greatly resisting medium. But what is the measure of great resistance? It is, as we have already said, that the resistance which opposes the motion shall bear a considerable proportion to the force which deflects the motion. But what is that force? Upon the theory of the universal gravitation of matter, on which theory we here proceed, the force which deflects the motions of the parts of each system into curves, is the mutual attraction of the parts of the system; leaving out of the account the action of other systems, as comparatively insignificant and insensible. The condition, then, for the production of such spiral figures as I have spoken of, amounts really to this; that the mutual attraction of the parts of the luminous matter is slight; or, in other words, that the matter itself is very thin and rare. In that case, indeed, we can easily see that such a result would follow. A cloud of dust, or of smoke, which was thin and light, would make but a little way through the air, and would soon fall downwards; while a metal bullet shot horizontally with the same velocity, might fly for miles. Just so, a loose and vaporous mass of cometic matter would be pulled rapidly inwards by the attraction to the centre; and supposing it also drawn into a long train, by the different density of its different parts, it would trace, in lines of light, a circular or elliptical spiral converging to the centre of attraction, and resembling one of the branches of the spiral nebulæ. And if several such cometic masses thus travelled towards the centre, they would exhibit the wheel-like figure with bent spokes, which is seen in the spiral nebulæ. And such a figure would all the more resemble some of these nebulæ, as seen through Lord Rosse's telescope, if the spirals were accompanied by exterior branches of thinner and fainter light, which nebulous matter of smaller density might naturally form. Perhaps too, such matter, when thin, may be supposed to cool down more rapidly from its state of incandescence; and thus to become less luminous. If this were so, a great optical power would of course be required, to make the diverging branches visible at all.

20. There is one additional remark, which we may make, as to the resemblance of cometary[16 - I am aware that some astronomers do not consider it as proved that cometary matter is entirely self-luminous. Arago found that the light of a Comet contained a portion of polarized light, thus proving that it had been reflected (Cosmos, i. p. 111, and iii. p. 566). But I think the opinion that the greater part of the light is self-luminous, like the nebulæ, generally prevails. Any other supposition is scarcely consistent with the rapid changes of brightness which occur in a comet during its motion to and from the Sun.] and nebular matter. That cometary matter is of very small density, we have many reasons to believe:—its transparency, which allows us to see stars through it undimmed;—the absence of any mechanical effect, weight, inertia, impulse, or attraction, in the nearest appulses of comets to planets and satellites:—and the fact that, in the recent remarkable event in the cometic history, the separation of Biela's comet into two, the two parts did not appear to exert any perceptible attraction on each other, any more than two volumes of dust or of smoke would do on earth. Luminous cometary matter, then, is very light, that is, has very little weight or inertia. And luminous nebulous matter is also very light in this sense: if our account of the cause of spiral nebulæ has in it any truth. But yet, if we suppose the nebulæ to be governed by the law of universal gravitation, the attractive force of the luminous matter upon itself, must be sufficient to bend the spirals into their forms. How are we to reconcile this; that the matter is so loose that it falls to the centre in rapid spirals, and yet that it attracts so strongly that there is a centre, and an energetic central force to curve the spirals thither? To this, the reply which we must make is, that the size of the nebular space is such, that though its rarity is extreme, its whole mass is considerable. One part does not perceptibly attract another, but the whole does perceptibly attract every part. This indeed need the less surprise us, since it is exactly the case with our earth. One stone does not visibly attract another. It is much indeed for man, if he can make perceptible the attraction of a mountain upon a plumb-line; or of a stratum of rock a thousand feet thick upon the going of a pendulum; or of large masses of metal upon a delicate balance. By such experiments men of science have endeavored to measure that minute thing, the attraction of one portion of terrestrial matter upon another; and thus, to weigh the whole mass of the earth. And equally great, at least, may be the disproportion between the mutual attraction of two parts of a nebulous system, and the total central attraction; and thus, though the former be insensible, the latter may be important.

21. It has been shown by Newton, that if any mass of matter be distributed in a uniform sphere, or in uniform concentric spherical shells, the total attraction on a point without the sphere, will be the same as if the whole mass were collected in that single point, the centre. Now, proceeding upon the supposition of such a distribution of the matter in a nebula, (which is a reasonable average supposition,) we may say, that if our sun were expanded into a nebula reaching to the extreme bounds of the known solar system, namely, to the newly-discovered planet Neptune, or even hundreds of times further; the attraction on an external point would remain the same as it is, while the attraction on points within the sphere of diffusion would be less than it is; according to some law, depending upon the degree of condensation of the nebular matter towards the centre; but still, in the outer regions of the nebula, not differing much from the present solar attraction. If we could discover a mass of luminous matter, descending in a spiral course towards the centre of such a nebula, that is, towards the sun, we should have a sort of element of the spiral nebulæ which have now attracted so much of the attention of astronomers. But, by an extraordinary coincidence, recent discoveries have presented to us such an element. Encke's comet, of which we have just spoken, appears to be describing such a spiral curve towards the sun. It is found that its period is, at every revolution, shorter and shorter; the amplitude of its sweep, at every return within the limits of our observation, narrower and narrower; so that in the course of revolutions and ages, however numerous, still, not such as to shake the evidence of the fact, it will fall into the sun.

22. Here then we are irresistibly driven to calculate what degree of resemblance there is, between the comet of Encke, and the luminous elements of the spiral nebulæ, which have recently been found to exist in other regions of the universe. Can we compare its density with theirs? Can we learn whether the luminous matter in such nebulæ is more diffused or less diffused, than that of the comet of Encke? Can we compare the mechanical power of getting through space, as we may call it, that is, the ratio of the inertia to the resistance, in the one case, and in the other? If we can, the comparison cannot fail, it would seem, to be very curious and instructive. In this comparison, as in most others to which cosmical relations conduct us, we must expect that the numbers to which we are led, will be of very considerable amount. It is not equality in the density of the two luminous masses which we are to expect to find; if we can mark their proportions by thousands of times, we shall have made no small progress in such speculations.

23. The comet of Encke describes a spiral, gradually converging to the sun; but at what rate converging? In how many revolutions will it reach the sun? Of how many folds will its spire consist, before it attains the end of its course? The answer is:—Of very many. The retardation of Encke's Comet is very small: so small, that it has tasked the highest powers of modern calculation to detect it. Still, however, it is there: detected, and generally acknowledged, and confirmed by every revolution of the comet, which brings it under our notice; that is, commonly, about every three years. And having this fact, we must make what we can of it, in reasoning on the condition of the universe. No accuracy of calculation is necessary for our purpose: it is enough, if we bring into view the kind of scale of numbers to which calculation would lead us.

24. Encke's comet revolves round the sun in 1,211 days. The period diminishes at present, by about one-ninth of a day every revolution. This amount of diminution will change, as the orbit narrows; but for our purpose, it will be enough to consider it unchangeable. The orbit therefore will cease to exist in a number of periods expressed by 9 times 1,211; that is, in something more that 10,000 revolutions; and of course sooner than this, in consequence of its coming in contact with the body of the sun. In 30,000 years then, it may be, this comet will complete its spiral, and be absorbed by the central mass. This long time, this long series of ten thousand revolutions, are long, because the resistance is so small, compared with the inertia of the moving mass. However thin, and rare, and unsubstantial the comet may be, the medium which resists it is much more so.

25. But this spiral, converging to its pole so slowly that it reaches it only after 10,000 circuits, is very different indeed from the spirals which we see in the nebulæ of which we have spoken. In the most conspicuous of those, there are only at most three or four circular or oval sweeps, in each spiral, or even the spiral reaches the centre before it has completed a single revolution round it. Now, what are we to infer from this? How is it, that the comet has a spiral of so many revolutions, and the nebulæ of so few? What difference of the mechanical conditions is indicated by this striking difference of form? Why, while the Comet thus lingers longer in the outer space, and approaches the sun by almost imperceptible degrees, does the Nebular Element rush, as it were, headlong to its centre, and show itself unable to circulate even for a few revolutions?

26. Regarding the question as a mechanical problem, the answer must be this:—It is so, because the nebula is so much more rare than the matter of the comet, or the resisting medium so much more dense; or combining the two suppositions, because in the case of the comet, the luminous matter has much more inertia, more mechanical reality and substance, than the medium through which it moves; but in the nebula very little more.

27. The numbers of revolutions of the spiral, in the two cases, may not exactly represent the difference of the proportions; but, as I have said, they may serve to show the scale of them; and thus we may say, that if Encke's comet, approaching the centre by 10,000 revolutions, is 100,000 times as dense as the surrounding medium, the elements of the nebula, which reach the centre in a single revolution, are only ten times as dense as the medium through which they have to move.[17 - We assume here that the number of revolutions to the centre is greater in proportion as the relative density of the resisting medium is less; which is by no means mechanically true; but the calculation may serve, as we have said, to show the scale of the numbers involved.]