Starting with a grotesque and clumsy hypothesis that we were to see, on the face of the full moon, a figure gradually becoming visible, representing a right-angled triangle, with a square constructed on each of its three sides as a base,'-as if, even on the supposition of there being human beings in the moon, it were not pre-eminently absurd to imagine that their selenometry must be at all analogous to our geometry, or that if they have Euclids with I. xlvii. all complete, that proposition must needs claim for them the admiration which we concede it; -the writer on the plurality of worlds discusses, in a rambling sort of a way, the general theory and conditions of intellectual progress. Advance is shown to be a necessary attribute of mental and moral existences. And all this in order to dilate on the self-evident proposition that: Even if there be intelligent inhabitants in the moon, or in the planets, it does not follow that they have any sympathy with us, or any community of knowledge:' a proposition which, so far from seeming to us to discredit the theory of a plurality of worlds, is, on the contrary, one of the most probable features in it. If science told us nothing of other spheres, how eminently unphilosophical would be the assumption that their tenants were modelled, physically or intellectually, upon one type! How does every branch of positive science demonstrate that such a conjecture would be not only unsafe, but improbable. It may be hard to imagine to ourselves the forms and qualities of moral and intellectual creatures distinct from mankind; but it would have been equally hard for angels, or other beings, to conceive of man before the Creator had modelled him, after His own image, and not upon any external type. It is necessarily impossible to picture to ourselves any object upon which none of our natural senses can be brought to bear; because, as Victor Cousin has so admirably shown, in his critique on Locke's Philosophy, the mind possesses its latent ideas all undeveloped and unexpressed until the operation of sensible impressions fertilises the womb of thought; and calls out into actuality and activity the ideas which lay dormant there. Hence the difficulty of imagining to oneself, or explaining to others, any object of mere abstract thought. The terms we use, when we employ language for the purpose, are all borrowed from the domain of sense; and thus

1 This strange and monstrous conception is, we believe, due to the originality of the gallant and eccentric Col. Thompson. He proposed to carve the figures above-described, in gigantic proportions upon Salisbury Plain, in the hope to elicit a response from the dwellers in the moon.

2 Of course the established relations of space are absolutely true everywhere, in the moon as well as in the earth. But her mathematical appliances may as far transcend our geometry and trigonometry, as these do the old arts of the Nilometricians [not however that we think it even probable the moon is a peopled world.]

the very vehicle and medium of our thought reminds us of the great disadvantages under which we labour, in attempting to discourse definitely about what is not the object of palpable

sensation.

But were we never so fertile and happy in our imaginings, how wild and visionary it would be to presume to people other worlds with creatures of our own imagination! We may, if we like to be absurd, people another planet with sentient and intelligent forms we can scarcely call them men-that shall combine all the hideous devices of ancient Indian, Egyptian, and Grecian mythologies or we may devise new shapes, beings with three legs, and possessed each of two minds, one of which is active, while the other takes its sleep. But, even if our notions were not necessarily and painfully grotesque, a well disciplined mind would at once recoil from any arbitrary assumptions of the kind, as unphilosophical. The problem is one in which the number of equations is utterly insufficient for the evaluation of all the unknown relations of the quantities involved. And even if the conditions were all ascertained, it by no means follows that we could solve a single one of them.

But the fact is, that modern science has told us a great deal about other worlds; and her intelligence furnishes us with a certain number of conditions which we can exhibit in, at any rate, an approximately explicit form. It is true that the information they afford us is negative. They only strip the possible inhabitants of other worlds of certain habits, or forms, or enjoyments, which obtain among ourselves. They supply no positive intelligence as to their actual mode of existence. They merely restrict it, in certain respects, within certain limits. Thus:

When we consider the physical peculiarities and probable condition of the several planets, so far as the former are known by observation, or the latter rest on probable grounds of conjecture, three features principally strike us as necessarily productive of extraordinary diversity in the provisions by which, if they be like our earth inhabited, animal life must be supported. These are-first, the difference in their respective supplies of light and heat from the sun; secondly, the difference in the intensities of the gravitating forces which must subsist at their surfaces, or the different ratios, which, on their several globes, the inertia of bodies must bear to their weights; and, thirdly, the difference in the nature of the materials of which, from what we know of their mean density, we have every reason to believe they consist. The intensity of solar radiation is nearly seven times greater on Mercury than on the earth, and on Uranus 330 times less the proportion between the two extremes being that of upwards of 2,000 to one. Let any one figure to himself the condition of our globe, were the sun to be septupled, to say nothing of the greater ratio! or were it diminished to a seventh, or to a 300th of its actual power. Again, the

1 Herschel, Outlines of Astronomy, p. 310.

material results, and positive acquisitions to the capital of ascertained facts, but that it greedily devours and discusses the guesses and counter-guesses of the wise.

Ever since the explosion of the old Ptolemaic doctrine, that our globe is the centre--if not the sum and substance-of all creation, a suspicion has been growing up, which has ranged, according to the constitution of different minds, from possibility to approximate conviction, that it may hold but a very insig nificant position in the universe. Dislodged from its ancient security, and hurled from the patient shoulders of Atlas through devious paths of space, demonstrated to thread its way about some other and nobler body in labyrinthal spirals, which constitute a very trifling part in the mazes traced out by the wanderers of the sky, the venerable earth became less and less the subject of blind and self-complacent adoration. What had been demonstrated to hold good of its physical relation to the rest of the universe-that this world plays but a most subordinate part in the system of creation-naturally suggested itself as a possible condition of its moral and intellectual position. Just as in the progress from infancy to maturity one learns gradually to abandon the narrow notions of infancy; as one's sympathies expand by degrees beyond the family circle; as the child drops by degrees the idea that papa, mamma, and nurse are the three most important potentates in existence, for whom, in fact, everybody else exists; as, finally, he learns that there are other, and perhaps brighter, homes, filled with wealthier inhabitants, more numerous, more important, or more fair; so it has been with the conception of the well-informed concerning the brother spheroids of our own system, the kindred systems which, with ours, constitute the galaxy, and finally the dim hazy nebula, which seem at least to be the galaxies of immeasurably distant heavens. It is, of course, by very gradual steps that such huge and bold generalisations are adventured. The progress of the opinion of mankind hereon has been very analogous to that which has occurred in the growth of individual thought. Every thinking man can probably recollect the difficulty he once had in understanding how it was that the earth was round like an orange,' and not flat, in indefinite extension, as had appeared to him when, elevated beyond the capabilities of his little legs, he was allowed to observe creation over the adjoining hedges. Then came the very hard lesson, that he was by no means to consider himself as defining the top' of the world; that good people in the antipodes were not at all standing on their heads, nor topsy-turvy, nor in any other than his own fashion. A good deal of confusion of ideas, and a slight sensation of vertigo, attended his efforts to eman

cipate himself from the idea that the sun really traversed the heavens. When the annual and diurnal motions had robbed him of all opinion of stability in all he had once considered immoveable, it remained to puzzle out how, so far from his own summer hay-fields and winter nights being the standard of the human family, there are people who experience every gradation of temperature, and every duration of day and night, from one hour to six months. At length, with repeated efforts and increasing years, the theory of his own globe is mastered. In spite of the confusion of ideas consequent on a consecutive perusal of Joyce's Scientific Dialogues,' he no longer imagines days to be long in summer, because things expand by heat, and to be short in winter, because they contract by cold. We cannot digress to trace the unobserved effect of other than astronomical studies, which, by a parallel advance, aid him in developing powers of generalisation, and in renouncing the foolish conceit that his interests, his world, his culture, and he, are the final causes and focal centre of all existence. From history, from classics, from art, and from politics, he learns the maxim, nihil humani alienum puto; from metaphysics and philosophy he learns to expand its scope even beyond the humani omne, as the Times in its peculiar Latinity would say; from religion he learns to feel sympathy with other than mundane matter; from all he learns to repudiate the absurdity, χρημάτων μέτρον ἄνθρωπος. Νot that all this progress is won at the stage whither we have already conducted him; but such is the tendency, and such or such-like the indirect influences, of a liberal education. So is his way paved to the more ready reception of the arcana of astronomy. To learn that the planets weave their mystic dance, not only around another than his own globe, but without the slightest reference to it, and without the slightest perceptible effect, for good or for evil, on its fortunes, must no longer present a difficulty to his mind. Step by step, he is learning the comparative unimportance of his habitation; gradually the idea of his own unimportance in the whole creation opens upon him as not impossible. Strange analogies and curious conjectures force themselves upon him, as he learns and admires the reproduction, in the case of the planets, of contrivances and phænomena with which he is familiar, and which had seemed to be peculiarly adapted to the use of intelligent and sentient beings. If he has been in the habit of contemplating with grateful admiration the arrangement whereby one satellite supplies the absence of sunlight, and that chiefly and most energetically when most required, what shall he conclude from the furniture of other planets, which, like his own, have day and night, and which accordingly enjoy satellites

proportioned in number and position to their needs? If it be any legitimate step in the argument from design, that our moon is longer above the horizon, and rides higher in the zenith, when our nights are longest and darkest, to what but design shall he attribute the arrangement in the motions of Jupiter's satellites, whereby it is impossible they should all be at once below the horizon? If the rotation of our earth, and the inclination of its axis of revolution to its orbitual plane, produce such obvious and useful effects on the vicissitudes of days and seasons, what shall be supposed the purpose of the like phænomena in planets more noble in their proportions than

our own?

We may well conceive such lines of thought to give rise to very curious conjectures in a contemplative mind, especially if the imagination be warm. But perhaps our astronomer, having learned many a lesson of cautious induction, and a wholesome dread of mere conjecture, in the school of practical science, forbears to proclaim, or even to encourage, the thoughts that brood within him. If strange fancies of previous existence on diverse orbs seem to him to involve, possibly, some distantly approximate solution of the mystic avάurnois, which comes at moments across us all, saying, I have been in this scene, or acted in this combination of circumstances before!' or if the congregation of different elements from different spheres on one terrestrial stage might haply account for the conflict of opinions, and sympathies, and interests around us, he checks such wandering imaginations as, perhaps, not altogether reverent, and certainly not as yet necessitated by any scientific induction. But still the semi-conviction remains,-- These wonders and complex systems were made for some use; their marvellous resemblance to our own suggests that that use was not wholly 'dissimilar from ours.'

We do not think that any valuable suggestion has ever been thrown out to explain the use of the planets to ourselves. There are, it would appear, persons to whom it seems satisfactory to imagine, that the kingly Jupiter with his attendant moons, the glorious Saturn and his triplicate girdle, the stately Uranus, and that interesting stranger,' whom the obstetric arts of Adams and Le Verrier guided to its birth (and whom the tardy incredulity of our observers has prevented our claiming as indisputably our own), exist, and have existed, only to win the admiring study of Chaldæan shepherds, to perplex the brains and tangled horoscopes of planet-stricken astrologers, to puzzle speculators, to furnish a Theory' for the Senate House, and finally to be gazed at by themselves through the great Northumberland! Or, perhaps, they deem it cause enough for the crea

6